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shearing strengths were, however, about the same
as in domestic cast irons of the same class, the car-
bon content being somewhat higher, and the silicon
and manganese contents considerably lower. Re-
sults of paint tests have not yet been completed.
2. Description of Bridge System
a. Topographical and Historical. The city of
Hiroshima was located upon the deltaic deposits
of the Ota River, a relatively short, fast-flowing
river which originated in the mountains north of
the city. This delta was situated at the end of one
of the few valleys running southwest to northeast
across the Chugoku mountain range. The Ota
River. flowing through the granite rocks of the
mountains, flooded the delta, leaving deposits of
earth and sand along the river beds. The beds, or
branches, named from east to west, became known
us the Enko-Gawa (River), Kyobashi-Gawa,
Motoyasu-Gawa, Temma-Gawa, Fukushima-Gawa,
and Yamate-Gawa. Eventually they separated
the delta into the seven islands of Hiroshima (Fig.
1). Hiroshima was at the junction of the sea and
land routes connecting Kyoto, Osaka, and Shimo-
noseki, and the northerly transmountain route to
the coast of the Japan Sea. Since early times
much importance had been attached to Hiroshima
as a communications center, as well as the military
and political headquarters of the Chugoku district,
b. Growth of Bridge System. The main thor-
oughfare was originally laid out around the foot
of the mountain range in a semicircle convex
northward and kept at a ground elevation above
the dangers of flood and tide. ‘Today the Sanyo
line of the government railways follows the old
highway in its route through Hiroshima toward
Shimonoseki, using Bridges 9, 26, and 50 (Fig. 1)
to cross the Kyobashi, Ota, and Yamate Rivers,
respectively. As the city spread southward with
the land reclamation projects which extended the
islands seaward, surface communications from
island to mainland and island to island required
an ever-increasing number of bridges to aecommo-
date not only the peak population of 380,000 per-
sons in Hiroshima, but also the traflie passing
through the city on the Inland Sea coastal
highway.
ce. Flood Effects on the System. A factor of
prime importance in the development of the bridge
system was the annual flood stages which the Ota
River and its branches reached during the typhoon
season from May through October. During these
months the rivers frequently rose as much as 15
33
feet above normal mean high water and caused
severe damage along their six beds by washing
away the alluvial deposits from around the foot-
ings of the piers and bents to such an extent (as
deep as 30 feet below normal grade) as frequently
to impair the structural safety of the bridges and
close them to traffic. In the Hiroshima area
foundation soils were of a sandy nature, rock bot-
tom being seldom encountered. To protect
against erosion, the foundations of piers for steel
and reinforced-concrete bridges were carried by
concrete caissons to depths of approximately 30
feet below the river bed. The typhoons of 17
September and 5 October 1945 caused considerable
additional damage to the bridges which had un-
dergone the atomic-bomb attack on 6 August.
d, Selection of Bridges for Study. Of the
many bridges found in Hiroshima by the team
upon its arrival on 14 October 1945, 57 were se-
lected for study in connection with physical
damage resulting from the atomic-bomb attack.
In this selection, primary considerations were
given to location, use, and construction. The
bridges (Fig. 1) ranged from 260 to 12.200 feet
from ground zero (GZ) and were scattered
throughout an approximate area of 12 square
miles. In use, they were classified as railroad,
street railWay, highway, pedestrian, aqueduct,
and mixed. The railroad bridges were princi-
pally in the northerly part of the city, the street
railway bridges in the center, and the others dis-
tributed over the city. Of the 57 bridges studied,
23 were steel, 19 timber, and 15 reinforced concrete.
e. Ownership and Maintenance. At the start of
the survey no estimate of damage had been pre-
pared by the governmental agencies, but repairs to
some damaged bridges were in progress, and
others were scheduled. Most plans and records
showing conditions prior to 6 August had been
destroyed by the atomic-bomb holocaust. How-
ever, according to the opinion of the city engineer,
approximately 80 percent of all bents and piers of
the city-owned bridges were in good condition
prior to the attack. The city had also repaired all
damage from the 1944 flood and the remaining
portions of the bridges had been checked over by
the bridge department of the city. All railroad
bridges maintained by the Japanese government
were in excellent condition and all the highway
bridges maintained by the prefectural govern-
ment were in a good state of maintenance. The
bridges carrying double-track street railways
maintained by the Hiroshima Electric Railway,
Ine. were also in good condition. In November
1945, at the time of the survey, as the rate of return
of residents increased, several bridges were under
repair and the city engineers were planning to
repair such others as was necessary to accommo-
date the flow of trafic along a northerly and south-
erly route through Hiroshima‘in order to prevent
traffic bottlenecks in the city. Under considera-
tion were Bridges 19, 31, 33, 45, and 46 which ac-
commodated the southerly route and Bridges 37,
13, and 48 which accommodated the northerly one.
In addition, the street-railway company had
planned to make whatever repairs were deemed
necessary to their own bridges. Bridge 13, the
most important, had been under repair since before
12 October 1945.
f. Bridge Design. Tnasmuch as most of the
records of Hiroshima were burned or destroyed,
little information was obtainable regarding the
design of the bridge structures. Therefore, it was
necessary to consult other sources, such as the
Hiroshima Electric Railway, the city engineers,
the prefectural government engineers and the gov-
ernment railroad officials, in searching for design
standards and other pertinent information,
From the few records available, and in many cases
from memory, these agencies furnished much of
the data incorporated in this section. Verified
and supplemented by observation, interrogation,
and inspection of documents, the data established
that four principal ownerships of bridges existed
in Hiroshima and that each differed somewhat
from the others in design practice. In most cases
the differences were explained by bridge use,
rather than by official prerogatives. All the de-
sign criteria are discussed in the following para-
graphs.
(1) Bridge Use. Inthe target area the bridges
varied widely in use. Of the 57 studied, 39 were
used to carry highway traffic (4 accommodated
both highway and street-railway traflic) ; 5 were
street-railway bridges; 6 carried railroads; 3 were
used as aqueducts; and 4 were for the use of pedes-
trians. One of the pedestrian bridges was unique,
being a Japanese Army suspension bridge with
steel cables and timber deck.
(2) Loading.
for a single concentrated load of 12 to 15 tons per
traffic lane.
whether or not the timber bridges were designed
for uniform loadings, earthquake, wind, or flood
Timber bridges were designed
The city engineers did not know
34
resistance. Timber piles were driven to a 4-ton
capacity at a depth of approximately 6 feet below
river beds by a pile driver with a 3.28-foot drop
and a 0.3-ton drop-hammer when concrete founda-
tions for the timber piles were omitted. In some
‘ases a concrete foundation approximately 10 feet
deep, 6 feet wide, and 12 to 20 feet long was con-
structed around pile bents. The length depended
on the number of timber piles per bent. The piles
were from 10 to 12 inches in diameter, approxi-
mately 30 feet long and extended into the concrete
about 1.5 feet below the top of the foundation.
Reinforced-concrete and steel-girder highway
bridges were designed for a uniform load of 100
pounds per square foot. Impact was taken as 30
percent of the live load. Concentrated loads of 12
tons per girder were taken as design loads for steel
bridges and 12 to 15 tons per traffic lane were taken
for conerete bridges. The prefectural-owned
bridges (Table 3) were designed for earthquake
resistance after 1922. Interrogation of the pre-
fectural government engineers indicated that
earthquakes were very light and rare in the Hiro-
shima area. Nevertheless, earthquake resistance
was taken into consideration for design purposes
by allowing 15 percent of the dead load as the over-
turning force for steel-plate girders and 30 percent
of the dead load as the overturning force for con-
crete piers acting at their respective center heights.
Information did not indicate whether these bridges
were designed for wind and flood resistance (Fig.
7). Railroad bridges were designed for Cooper's
E-40 live load. No other information could be
secured through interrogation in regard to design
data.. However, interrogation did disclose that the
railroad engines were known as class D-51, weigh-
ing approximately 77 tons, and class D-52, weigh-
ing approximately 85 tons. The largest passenger
car had a net weight of 35 tons and a gross weight
of 50 tons, while the largest freight car had net
and gross weights of 27 and 50 tons, respectively.
Street-railway bridges carried a double-track rail-
way. These bridges were designed for a total load
of 26 tons which included earthquake resistance,
passenger loading, and weight of street car. No
other information in regard to design data was
available except that, through interrogation, engi-
neers stated that both the earthquake-resistance
factor and the distributed load produced by the
passengers in streetcars were reduced to equivalent
concentrated loads for design. For purposes of
design, a total load of 3.25 tons per streetcar wheel
TABLE 2.—Street-railway bridges (schedule of materials)
Temma-Gawa Bridge (Bridge 35) (typical)
Description : Weight Num- Total
Section and weight . 5 re-
(per linear foot) Length Peouneia) —— Phone
Feet Inches |
I-beams.___ - 15 by 5 inches by 42 pounds 23. «0 =| 966 4 (3, 864. 00
Angles. 6 by 6 by 716 inches by 17.2 pounds___- ~~ 2 18 6 318. 2 2 634. 40
Do |. do. ; Song 18 0 | 309.6 2} 619. 20
Do. 6 by 6 by % inches by 14.9 pounds______ {mle 0 14.9 32 476. 80
Do_ 3\% by 3 by % inches by 7.9 pounds = 112 9 | 100, 73 2} 201. 46
Do do 3 shat } 12 3 96. 78 2 193. 56
Plates : 24 by % inches by 30,6 pounds aS 1284) ae bo 4 306, 00
Do_. 18 by % inches by 22.96 pounds. ________- 2 0° | 48:92 4 | 183.58
Digs ss 15 by % inches by 19.14 pounds_ ES Z 1 6 28. 71 8 229. 68
Do. 9 by % inches by 11.48 pounds - 2 3%/| 26. 55 2; 53.10
Rivet__- % inch in diameter__—_—_. SiS s | 0.123) 792 | 97. 42
Total weight per bent___. RE a a Bee : _\6, 861. 31
was used. The company used two types of cars
known as 4 car, weighing 18 tons (empty) and 2
car, weighing 14.7 tons (empty). In bridge de-
sign, cars A and B were assumed to weigh 26 tons
fully loaded. The designers also assumed that a
car when fully loaded would carry 160 persons.
Each person was assumed to weigh 111 pounds and
the approximate total passenger load was, there-
fore, 8.8 tons per car (Fig. 7).
(3) Stresses. The working stresses for timber
bridges were not ascertainable. It was estab-
lished, however, that working stresses of 16,000
pounds per square inch were used for steel and
640 pounds per square inch for concrete. The re-
inforced-concrete bridges were designed for con-
crete having an ultimate strength of 2,000 pounds
per square inch in compression and for working
stresses as follows: Tension, 64 pounds per square
inch: shear, 64 pounds per square inch; compres-
sion, 640 pounds per square inch; compression in
flexure, 640 pounds per square inch; except that
prefectural government engineers used 500 pounds
per square inch for concrete in compression. ;
g. Construction, Generally, the design, details,
and arrangements for timber, concrete, steel-plate-
girder, and rolled-section I-beam bridges used for
both highway and street-railway traflic appeared
to be below United States standards. The steel-
plate-girder bridges for railroad traffic and steel-
truss aqueducts compared favorably with similar
structures in the United States.
(1) Timber — Bridges. Field investigations
showed that floor beams were not used and that
35
stapled connections were used instead of bolts.
Connections were not rigid over pile bents and
bolster plates were placed directly beneath timber
girders. Diagonal bracing for timber piling was
insufficient. Rough log members were used in sev-
eral bridges instead of dimension timber (Fig. 19).
(2) Steel Bridges employed girders haunched at
supports as a general practice, and the continuity
of spans was discarded in favor of cantilever de-
sign, due to poor foundations and piers which fre-
quently settled. Rocker plates were used in some
bridges at supports (Figs. 3 and 4).
(3) In Reinforced-Concrete Bridges haunching
of girders at supports was common practice and
cantilever design was substituted for span con-
tinuity over supports because of poor foundations
and piers which frequently settled. Floor beams
were not used. However, a greater number of
closely spaced, concrete longitudinal beams was
employed, thereby transmitting the deck loads
directly to the abutments and bents. The con-
struction of railings, ornamental posts, caps, cop-
ings and curbs would have been comparable with
United States standards of construction if they
had been properly anchored, keyed or doweled to
the structures (Photos 13 and 36, and Fig. 8). In-
terrogation and inspection showed that the splicing
of reinforcing bars was not practiced.
h. Materials. In general, the quality of mate-
rials appeared to be below United States standards.
An exception was the steel employed in bridge
structures which in size and appearance were com-
parable with United States standards.
(1) Zimber. Field inspections showed that
timber materials were considerably below United
States standards. No evidence indicated that
timber was treated with creosote or other pre-
servatives. Dimensions were not normally of
commercial sizes, and in many cases rough logs
were used in the structures. In no case did the
team find that timber bridges had received a pro-
tective coat of paint.
(2) Concrete. The aggregates used for con-
crete were sand and gravel from the local river
beds, the former being unscreened. Gravel, how-
ever, was screeneidl in an attempt to obtain some
gradation, with maximum size stones of 2 to 3
inches. The cement was manufactured and ob-
tained from the Ube Cement Co. and the Oroda
Cement Co., both located in Tamaguchi Prefee-
ture. Some cement was obtained from the nearby
Asano Cement Co.
(3) Steel. Sizes of bars varied from 14 to 114
inches in diameter for steel reinforcing. Rein-
forcing for deck slabs varied from one-fourth to
five-eighths inch in diameter. Stirrups were of
various types and sizes. Temperature reinforce-
ment was not used nor were square steel rods.
Deformed reinforcing bars were not used princi-
pally because they were 50 percent more costly
than plain bars. Rolled-steel I-beams were of
standard sizes, reinforced against buckling by dia-
phragms and angle stiffeners. All materials (Ta-
ble 2) were usually of medium steel and appeared
to be comparable with United States standards.
Steel received one shop coat of red-lead paint be-
fore shipment, and protective field coats later.
A cast metal sign fastened to the face of the girders
of railroad Bridge 51 showed the shipment and
manufacturing of the materials as follows (Photo
109) :
Materials: Angles, LJG Steel Works, Kawa-
saki Zosenshokobe.
Plate: Asano Zosen Seihambu.
Rivets: Asano Rokuro Seikosho.
3. Analysis of Damage
a. Chronology and Use of Data.
the damage to Hiroshima by the atomic bomb a
difficult problem was to distinguish between bomb
damage and flood and typhoon damage which came
later. Since this complexity of damage was
especially evident in the bridge system, it was felt
that a chronological consideration of damage in-
cidents and other data would serve as a valuable
check list. Therefore, the cause and extent of
In assessing
36
damage to each bridge was established only after
it had been carefully considered in relation to each
of the following:
(1) Preattack air photos, dated 13 April 1945.
(2) Atomic-bomb damage of 6 August 1945,
(3) Postattack air photos, dated T August 1945,
(4) Flood damage of 17 September 1945.
(5) Flood and typhoon damage of 5 October
1945,
(6) Field observation from 14 October
through 24 November 1945.
(7) Japanese drawings and documents.
(8) Interrogation of eyewitnesses and officials.
It is noteworthy that in the interval bet ween the
dropping of the atomie bomb and the arrival of
the team two months later there occurred two
severe storms, of which at least one had an in-
tensity such as would be encountered only once in
perhaps 50 or 100 years. These storms, unfortu-
nately, destroyed much evidence of bomb action to
bridges when they washed away the damaged
structures,
b. Method of Analysis, Each of the 57 bridges
selected for study was numbered and its location
in relation to the point of detonation of the bomb
(air zero, or AZ), and the point on the ground
directly below AZ (ground zero, or GZ) was estab-
lished (Fig. 1). Each individual bridge was then
studied in detail with respect to its use, design,
materials, special features, strength, quality of
construction, cause of damage and extent of dam-
age. Photographs of the bridges were taken to
show the condition of the structures at the time of
the field survey.
ce. Definition of Terms. The damage, resulting
from many causes occurring at different times, had
left an analysis problem of considerable com-
plexity. Therefore, for assessment, evaluation,
and tabulation, the following classifications of
damage was adopted by the survey.
(1) Yotal Damage. Damage requiring replace-
ment of the entire bridge, or from 90 to LOO percent
of spans and piers or bents.
(2) Severe Damage. Damage to the major
part of the structure, requiring replacement. of
between 50 and 90 percent of the spans and piers
or bents.
(3) Moderate Damage. Damage to the spans,
piers or bents that could be repaired in a rela-
tively short time; structural damage requiring re-
placement of between 10 and 15 percem of the
spans and piers or bents.
TABLE 3.—Prefectural government bridges
, Approxi-
greg Type Use Phcapete
| structed
as : ga So
5 | Concrete. - * ; _.| Highway _- | 1925
8 | 1) ee fs 1933
12 | Plate girder. —__ sy: do. 1927
16 | Conerete ee eee 1935 |
17 | Plate girder. .______- do 1925
20 Girder I-beam __ a} do. 1921
22 | Plate girder________- d62 2 1925
24 a005—. = =. _do- 1931
25 Concrete EA _do- 1932
27 | Steel-arch =" do_ 1922
29 | Steel-truss__.- .. .-- do 1890
$9 | tinben sores coecee [03 Agee NK
37 | Plate girder_-_-_- oe _do 1926
ET Te! 8) 0 aaa aE RC { e 1920
48 | Plate girder______-- do. 1925
Earthquake-
resistance Remarks
design
Yeosse.< Nore.—(1) After the year 1922, all prefectural
Yes._.___| government bridges were designed for earthquake
Yes__.---| resistance.
fee (2) Some of these bridges were also maintained
Yes__.___| by other agencies of Hiroshima.
Nofe2. (3) NK= Not known.
Yes.
Yes__
Yes.
Noo. os
No
No
Yes_-
Noes.
Yes__
(4) Slight Damage. Damage necessitating a
minimum of repair to open the bridge to traffic;
structural damage requiring replacement of be-
tween 0 and 10 percent of the spans and piers or
bents.
d. Damage to Timber Bridges. Texamination
was made of 19 bridges of timber construction, of
which 8 were either partly damaged or totally
damaged by fire; but 3 (Bridges 6, 15, and 43) were
initially damaged by blast; 2 (Bridges 38 and 39)
were initially damaged by fire and later totally
damaged by flood; one (Bridge 40) was severely
damaged by fire only; and 2 (Bridges 14 and 34)
were totally damaged by fire. Therefore, of the
19 timber bridges, 6 (Bridges 28, 32, 36, 43, 46, and
49) were partly or completely damaged by flood,
8 (Bridges 6, 153A, 14, 34, 38, 39, 40, and 43) by
fire, 1 (Bridge 21) by blast and flood but initially
by blast, and 4 (Bridges 1, 11, 15, and 18) were
undamaged. The timber bridges were located
from 1,450 feet (Bridge 21) to 9,800 feet (Bridge
1) from GZ. For details and sketches, Figures 19
and 20,
(1) Bridge 1 (9800 feet from GZ and 10,000
feet from AZ) was the most remote bridge studied.
This bridge suffered no damage (Photos 1 and 2).
(2) Bridge 6 (5370 feet from GZ and 5,730 feet
from AZ). The approximate midportion of this
bridge was slightly damaged initially by blast and
later was totally damaged by fire (Photo 11).
(3) Bridge 11 (7,960 feet from GZ and 8,200
feet from AZ) suffered no damage (Photos 19-23).
(4) Bridge 134A (4.670 feet from GZ and 5,080
feet from AZ). The span adjacent to the west
abutment was slightly damaged initially by blast
and later the whole bridge was totally damaged
by fire (Photos 31 and 32).
(5) Bridge 14 (4,760 feet from GZ and 5,170
feet from AZ) was totally damaged by fire (Photo
33).
(6) Bridge 15 (5580 feet from GZ and 5,900
feet from AZ) suffered no damage (Photo 34).
(7) Bridge 18 (6000 feet from GZ and 6,300
feet from AZ) suffered no damage (Photo 37).
(8) Bridge 21 (1450 feet from GZ and 2460
feet. from AZ) was the nearest timber bridge to
GZ. This bridge suffered slight structural dam-
age. Spans at approximately the bridge center
were totally damaged by the blast which also
weakened the remaining timber spans, damaged
the deck and totally damaged part of the timber
railings along both sides of the bridge structure.
Ata later date this bridge was totally damaged by
flood with the exception of part of one span adja-
cent to the west abutment (Photo 42).
(9) Bridge 28 (4430 feet from GZ and 4,840
feet from AZ) was totaly damaged by flood (Fig.
19, and Photo 76).
(10) Bridge 32 (9A00 feet from GZ and 9.600
feet from AZ). The approximate middle portion
of the bridge was severely damaged by flood
(Photo 8&8).
(11) Bridge 34 (3.700 feet from GZ and 4,200
feet from AZ) was totally damaged by fire (Photo
90).
(12) Bridge 36 (3.200 feet from GZ and 3,760
37
feet from AZ) was totally damaged by flood
(Photo 93),
(13) Bridge 38 (3750 feet from GZ and 4,250
feet from AZ). Initially the westerly half of the
bridge was severely damaged by fire spreading
from adjoining areas and later was totally dam-
aged by flood (Photo 95).
(14) Bridge 39 (3,880 feet from GZ and 4.590
feet from AZ). The easterly half of the bridge
was initially moderately damaged by fire spread-
ing from adjoining areas and later was totally
damaged by flood (Photo 96).
(15) Bridge 40 (5360 feet from GZ and 5,700
feet from AZ). The northerly portion of this
bridge was severely damaged by fire (Photo 97).
(16) Bridge 42 (5100 feet from GZ and 5490
feet from AZ) was totally damaged by flood
(Photo 99).
(17) Bridge 43 (5180 feet from GZ and 5,510
feet from AZ). The approximate midspan of this
bridge was slightly damaged initially by blast and
fire and later was totally damaged by flood (Photo
100). Norr.—A new timber bridge was con-
structed.
(18) Bridge 46 (8,090 feet from GZ and 8.350
feet from AZ) was totally damaged by flood
(Photo 103).
(19) Bridge 49 (6380 feet from GZ and 6,650
feet from AZ) was totally damaged by flood
(Photo 106).
e. Damage to Reinforced-Conerete Bridges.
study was made of 15 reinforced-concrete bridges
(3, 4,5, 7,8, 10, 16, 19, 25, 30, 31, 33,41, 45, and 52)
(Fig. 1). They varied from 1,930 to 12,200 feet
from GZ. Bridge 52, 12,200 feet from GZ, was
the most remote of all the bridges studied.
None of the reinforced-concrete bridges was
structurally damaged by the atomic bomb. Sev-
eral bridges, however, did suffer superficial
damage from bomb effects, such as broken or dam-
aged railings, dislodged ornamental posts, caps,
and coping curbs, Of the 15 reinforced-concrete
bridges, 5 (3, 10, 30,33, and 45) were damaged by
flood only; 3 (4, 8, and 19) suffered superficial
damage by blast ; 2 (25 and 31) suffered damage by
flood and later received superficial damage by
blast ; and 5 (5, 7, 16,41, and 52) were undamaged.
For sketches, Figures 2-6, inclusive.
(1) Bridge 3 (7,130 feet from GZ and 7,390 feet
from AZ). The spans and piers adjacent to the
south abutment were severely damaged by flood
( Photos 47).
38
(2) Bridge 4 (6450 feet from GZ and 6,750 feet
from AZ). This bridge suffered no structural
damage but received superficial damage from the
blast which blew off the northwest corner concrete
railings (Photo 8).
(3) Bridge 5 (6,210 feet from GZ and 6,510 feet
from AZ) suffered no damage (Photo 10).
(4) Bridge 7 (5,200 feet from GZ and 5,570 feet
from AZ) suffered no damage (Photo 12).
(5) Bridge 8 (5.390 feet from GZ and 5,700 feet
from AZ). This bridge suffered no structural
damage but received superficial damage from the
blast which blew off the concrete railings along
both sides (Photo 13).
(6) Bridge 10 (6,950 feet from GZ and 7,250 feet
fron AZ). The spans and piers adjacent to the
south abutment were moderately damaged by flood
(Photo 18).
(7) Bridge 16 (5,750 feet from GZ and 6,100 feet
from AZ) suffered no damage (Photo 35).
(8) Bridge 19 (4270 feet from GZ and 4,720
feet from AZ). This bridge suffered no strue-
tural damage but received superficial blast damage
indicated by dislodged ornamental posts (Photos
38 and 388A).
(9) Bridge 25 (5200 feet from GZ and 5570
feet from AZ). The fourth bent from the south
abutment was completely washed out by flood, but
the bridge continued to carry unrestricted traffic.
It also received superficial damage when blast blew
off the concrete coping along both sides and
slightly damaged the railing balusters directly
over each pier (Photo 71 and Fig. 15).
(10) Bridge 30 (1,930 feet from GZ and 2,800
feet from AZ), the nearest concrete bridge to GZ,
was severely damaged by flood only (Photos 81-84
and Fig. 16).
(11) Bridge 31 (4,570 feet from GZ and 5,000
feet from AZ) suffered severe damage by flood
(Photo 87).
(12) Bridge 32 (5300 feet from GZ and 5.650
feet from AZ) suffered severe damage by flood
(Photo 89).
(13) Bridge 41 (6150 feet from GZ and 6460
feet from AZ) suffered no damage (Photo 98).
(14) Bridge 45 (7,010 feet from GZ and 7,300
feet from AZ). The spans and bents adjacent to
the east abutment were moderately damaged by
flood (Photo 102).
(15) Bridge 52 (12,200 feet from GZ and 12,450
feet from AZ) suffered no damage. This bridge
was the most distant bridge studied from GZ
(Photo 110).
f. Damage to Steel Bridges. A study was made
of 23 steel bridges (2, 5A, TA, 8A, 9, 12, 13, 17, 20,
29, 23, 24, 26, 27, 29, BOA, 35, 36, BT, 44, 47, 48, 50,
and 51) which ranged from 260 to 7,600 feet from
GZ. Bridge 22 was the nearest to GZ, being only
260 feet therefrom, while Bridge 17 was the most
distant steel bridge from GZ, being at 7,600 feet.
Of 23 bridges studied, 1 (Bridge 29) was totally
damaged by blast; 2 (24 and 30) suffered slight
structural damage by blast; 5 (12, 17, 20, 22, and
23) received superficial blast damage: 5 (9, 26, 27,
50, and 51) suffered no structural damage, but
bomb effects were indicated by discoloration of the
old paint on the steel members facing the direction
of the blast; 1 (13) was initially damaged by blast
and later moderately damaged by flood; 1 (37)
was severely damaged by flood; 1 (35) was to-
tally damaged by flood; and 7 (2, 5A, TA, SA, 44,
47, and 48) were undamaged. For sketches, Fig-
ures 2-6, inclusive.
(1) Bridge 2 (SA80 feet from GZ and 8,740 feet
from AZ) suffered no damage (Photo 3).
(2) Bridge 5A (6160 feet from GZ and 6470
feet from AZ) suffered no damage (Photo 10),
(3) Bridge 7A (5240 feet from GZ and 5,600
feet from AZ) suffered no damage (Photo 12).
(4) Bridge SA (5580 feet from GZ and 5,900
feet from AZ) suffered no damage (Photo 14).
(5) Bridge 9 (5,730 feet from GZ and 6,050
feet from AZ) suffered no structural damage but
bomb effects resulted in the discoloring of the old
paint on the steel members along the south side
facing the flash. The north side was unaffected
(Photes 15-17 and Pig. 17).
(6) Bridge 12 (4,700 feet from GZ and 5,100 feet
from AZ). This bridge suffered no structural
damage but received superficial blast damage indi-
cated by dislodged stone ornamental posts at its
southwest corners (Photos 24, 25, and 26).
(7) Bridge 13 (4,670 feet from GZ and 5,080 feet
from AZ) was damaged by blast and flood. Ini-
tially this bridge suffered slight damage by blast,
especially to the bents supporting the center por-
tion of the bridge, and to the I-beam girders located
at the approximate bridge center, At a later date
it was moderately undamaged by flood (Photos
27-30 and Fig. 18).
(8) Bridge 17 (7,600 feet from GZ and 8,870 feet
from AZ). This bridge suffered no structural
damage, but received superficial blast damage,
39
both concrete railings of the main spans being
totally damaged. The railings of the approach
spans were not damaged by blast (Photo 36).
Thiswas the most remote plate-girder bridge
from GZ.
(9) Bridge 20 (I-beam girder, 2,900 feet from
GZ and 3,450 feet from AZ). This bridge suffered
no structural damage by blast which, however, dis-
lodged ornamental corner posts (photos 39, 40,
and 41).
(10) Bridge 22 (260 feet from GZ and 2.020 feet
from AZ). Of plate-girder design, this was the
nearest bridge to the zero points. It had four steel
longitudinal girders arched at the center and
haunched at their supports. The piers were con-
crete, faced with masonry. The roadway deck was
of reinforced concrete with asphalt-wearing sur-
face. The ornamental stone posts, two at east and
west abutments and two at each river pier, were
connected by concrete railings (Photo 438A). The
bridge suffered no structural damage, although the
north faces of the piers showed minor damage due
to exposure to the blast. It did, however, receive
superficial damage as the concrete railings on both
sides were totally damaged and the ornamental
posts were dislodged in a direction away from GZ
(Photos 43-46 and Fig. 9). It appeared that the
girders of the end span had lifted and had been
slightly displaced at the abutments. The center
span appeared to have been deflected and caused
to rebound by the action of the blast which had
shaken the entire bridge. Evidence also indicated
that the joints of the water main spanning the river
between the girders underneath the bridge were
slightly damaged.
(11) Bridge 23 (860 feet from GZ and 2.170
feet from AZ). This plate-girder bridge suffered
no structural damage, but received superficial blast
damage totally damaging the concrete railings
along both sides. The east railing was blown into
the river and the west railing was blown toward
GZ onto the roadway deck which indicated the
instantaneous and rebound effects of the bomb
blast (Photos 48 and 49). The cast-iron posts
encased in the concrete railings were sheared off
at curb elevation. The railings were anchored
quite securely at the conerete deck and curbs. This
anchorage was provided by the cast-iron posts
which were bolted to the outside girder and spaced
® feet on centers (Fig. 10 and Photos 48 and 49).
The ornamental posts at the southeast and south-
west corners of the bridge were slightly dislodged.
The longitudinal girders received no damage and
there was no indication of displacement of the
abutment at the south end of the bridge. The
longitudinal girders abutting the south face of
Bridge 24 were of cantilever design and showed no
indication of deformation (Photos 47 and 70).
(12) Bridge 24 (1.000 feet from GZ and 2.230
feet from AZ) was located at the intersection of
the Oia and Motoyasu Rivers (Photo 70). This
bridge of plate-girder design received physical
damage of a spectacular and interesting nature
but it continued to carry unrestricted highway,
pedestrian, and street railway traffic. The longi-
tudinal steel girders suffered no great structural
damage although a slight lateral deformation in-
(licated that they had been highly stressed. It was
also apparent that the bridge had first been de-
pressed by the blast, and then the girders re-
bounded upward due to the elastic quality of the
steel, Apparently the reflection of the blast wave
from the river and the rebounding action raised
the roadway and sidewalk slabs from their sup-
porting girders and also moved them laterally at
the west end spans of the bridge (Photos 58 and
69) ina direction away from the blast. Although
the girders were subjected to large and unusual
stresses, the elastic limit of the material was not
greatly exceeded. The longitudinal girders, how-
ever, did suffer slight deflection, especially those
girders under the concrete walk adjacent to the
east abutment where they were deflected approxi-
.
mately 2 to 3 inches downward at the center of the
span (Photos 62 and 63), and there was a slight
lateral deflection (Photos 53, 66, and 67). The
girders at the west abutment showed an indication
of deformation (Photo 64). The longitudinal
girders of the fourth and fifth spans from the east
abutment underneath the north walk were slightly
deformed laterally and vertically, indicating that
stresses were built up in the web-plate and bottom
flanges at the piers. The concrete railings were
totally damaged. The cast-iron posts encased in
the concrete railings were sheared off at curb level,
apparently as a result of severe shock effects pro-
duced by the blast. The railings were anchored
securely to the conerete deck and curbs. This an-
chorage was provided by the cast-iron posts which
were bolted to the outside girder and spaced 6 feet
on centers (Photo 61). Other interesting damage
features occurred at Bridge 24, such as damaged
walks, roadway deck, and granite curbs. These
damage features resulted from the shifting of the
roadway deck laterally and vertically due to bomb
effects. The concrete walk along the north side
was pushed approximately 3 feet above its sup-
porting members over the center span (Photo 65).
Along the north gutter, the scupper drains were
left approximately 2 feet above the roadway be-
cause the deck was raised so high off the steel and
shifted so far that the seupper pipes hit on girders
in falling (Photos 54.55.57). Approximately at
the bridge center the roadway deck was shifted
laterally 15 inches north and raised approximately
14 inches above its original position (Photos 54, 55,
57, and 65). When raised and shifted laterally,
the edge of the slab landed on the sidewalk-sup-
porting steel which was at a higher elevation
(igs. 11 and 12). Also at approximately bridge
center (opposite Bridge 23) the rails of the south
street railway track were raised about 8 inches
above their original position. This movement was
caused by reflected blast which, however, did not
affect Bridge 23 because of the nonrigid connection
of the cantilever span abutting the south face of
Bridge 24 (Photo 60). The southwest area of
Bridge 24 was also affected by blast which raised
the concrete walk approximately 20 inches above
its original elevation and displaced the granite
curb laterally 914 inches north from its original
position. The roadway concrete deck, concrete
walk, and granite curb at the northwest corner of
the bridge (Photo 59) were also damaged by blast.
The shifting of the bridge deck caused a slight lat-
eral deflection in the street railway rails at the east
end of the bridge (Photo 68) and also moved the
rails laterally 15 inches to the north from their
original position at the west end of the bridge
(Photo 69). The ornamental stone caps at the cor-
ners of Bridge 24, with the exception of the south-
east posts, were dislodged by the bomb effects ( Fig.
12and Photo 70). It was learned through interro-
gation that at the time of the blast approximately
300 Japanese soldiers and many civilians were
crossing the bridge and all were hurled into the
river,
(13) Bridge 26 (5450 feet from GZ and 6,100
feet from AZ) suffered no structural damage.
The bomb effects, however, discolored the old
paint on the steel members along the south side
facing the direction of flash. The north side was
unaffected (Photos 72, 73, 74).
(14) Bridge 27 (4.360 feet from GZ and 4.790
feet from AZ) suffered no structural damage, but
the bomb effects discolored the old paint on the
steel members along the east side. The members
along the west side were less affected (Photo 75).
The bridge was of tied-arch single-span construe-
tion.
(15) Bridge 29 (1190 feet from GZ and 2,310
feet from AZ), a pin-connected steel truss, was
totally damaged by blast. Only stone-faced con-
crete piers and abutments remained. The blast
forces reflected from the water struck the bridge
from below and caused an uplift, while the blast
striking along the sides caused overturning and
failure of the structure which collapsed into the
river downstream (Fig. 14). The approximate
center height of the trusses was 13 feet above road-
way grade. Interrogation indicated that this
bridge was approximately 55 years old. It was a
highway bridge of very light construction with
timber deck and asphalt-wearing surface, and was
in fair condition (Photos 77-80).
(16) Bridge 30A (A880 feet from GZ and 2,750
feet from AZ) suffered slight damage by blast.
This bridge, known as the Shinobashi Aqueduct,
carried a 16-inch water main, It was the nearest
steel water crossing to GZ, It was a bow-string
truss, built of light, steel angle members, and was
supported on concrete piers. The blast caused
slight deformation of the truss members. The
members adjacent to the west abutment were most
severely affected by the blast, and evidence indi-
cated that the deformation of the members was
caused by direct blast forces rather than by forces
reflected from the water (Photos 85 and 86),
(17) Bridge 35 (3.190 feet from GZ and
feet from AZ) was totally damaged by
(Photos 91 and 92).
(18) Bridge 37 (3.220 feet from GZ and 3.770
feet from AZ) suffered severe damage by flood
which destroyed one pier and two spans adjacent
to the west abutment (Photo 94).
(19) Bridge 44 (5300 feet from GZ and 5,650
feet from AZ) suffered no damage (Photo 101).
(20) Bridge 47 (7A50 feet from GZ and 7,700
feet from AZ) suffered no damage (Photo 104).
(21) Bridge 48 (7.130 feet from GZ and 7400
feet from AZ) suffered no damage (Photo 105).
(22) Bridge 50 (6580 feet from GZ and 6,900
feet from AZ) suffered no structural damage, and
the only bomb effect noted was discoloration of the
old paint on the steel members along the south side
facing the direction of flash. The north side was
unaffected (Photo 107).
(23) Bridge 51 (6450 feet from GZ and 6,780
feet from AZ) suffered no structural damage. The
3,750
flood
41
only indication of bomb effect was discoloration of
the old paint on the steel members along the south
side facing the direction of flash. ‘The north side
was unaffected (Photos 108 and 109).
g. Recapitulation of Damage to Steel Bridges.
The 23 steel bridges accommodated 4 types of traf-
fic, with the exception of 3 bridges which carried
water crossings,
(1) Railroad Bridges. Of the total number of
steel bridges, five were railroad bridges carrying a
double-track (Bridges 8A, 9, 26, 50, and 51).
Bridge 2 carried a single track railroad, These
bridges were located from 5,730 feet to 8480 feet
from GZ, Bridge 2 being the most distant. ‘They
were built-up, plate-girder sections and suffered no
damage.
(2) Aqueduets. Three of the total number of
steel bridges were used as water crossings. Of
these, Bridge 30A was slightly damaged by blast.
The others (Bridges 5A and 7A) suffered no dam-
age (Photos 10, 12, and 85). Bridge 30A was the
nearest aqueduct to GZ,
(3) Street Railway Bridges. There were 4 steel,
street-railway bridges of rolled I-beam sections
supported by H-column bents with diagonal brac-
ing. These were Bridges 13, 35, 44, and 47, which
carried double-track, street-railway traflic. Of
these, 1 was completely destroyed by flood. One
was initially damaged by blast and later moder-
ately damaged by flood. ‘Two suffered no damage
These bridges were located at 4,670 to 7450 feet
from GZ, Bridge 47 being the most distant.
(4) Highway Bridges. Yen of the total num-
ber of steel bridges studied carried highway traffic.
Of the 10, 1 (Bridge 27), a tied-arch, suffered no
damage; 1 was a pin-connected steel truss (Bridge
29) which was totally damaged by blast; one was
an I-beam girder section with angle stiffeners sup-
ported by H-column bents with diagonal bracing
(Bridge 20), which suffered only slight superficial
damage, and the remaining seven (Bridges 12,
17, 22, 23, 24, 37, and 48) were built-up, plate-
girder sections supported on conerete piers.
These bridges were located from 260 to 7,600 feet
from GZ. Bridge 17 was the most remote high-
way, plate-girder bridge from GZ. Of these, 4
(Bridges 12, 17, 22, and 23) received superficial
damage, and 1 (Bridge 24) received slight struc-
tural damage by blast. Bridge 37 was severely
damaged by flood. Bridge 48 suffered no damage.
h. Résumé of Fire Damage to Bridges. Five
damaged eight timber bridges and was the cause
of negligible damage to two steel bridges. There
was no fire damage to concrete bridges. The eight
timber bridges were ignited by fire spread from
nearby combustible areas.
(1) Thirteen of the nineteen timber bridges
studied (6, 135A, 14, 15, 18, 21, 28, 34, 36, 38, 39, 40,
and 43) (Fig. 20) were within the burned-over
area. Of the 15,7 were totally or partly damaged
by fire on the day of the attack, and 1 other was
partly damaged by fire 3 days later. One end of
Bridge 42, a timber structure, was adjacent to the
burned-over area, but sustained no fire damage.
The 5 timber bridges (1, 11, 32, 46, and 49) which
were outside and not adjacent to the burned-over
area were not fire damaged.
(2) Timber Bridges 6, 13A, and 43 were dam-
aged initially by blast and later ignited by burning
buildings and totally damaged. The other timber
bridges which burned had not been blast damaged,
Bridges 14 and 34, ignited by burning buildings
at both ends were totally damaged. Thirty percent
of the east section of Bridge 39 was totaly damaged
by fire which spread to it from burning buildings
at the east end. Fifty-five percent of the north
end of Bridge 40 was totally damaged by fire which
spread to it from burning buildings at the north
end.
(3) Timber Bridge 38 was neither damaged by
blast nor by fire on the day of the attack, but 3
days later 50 percent of the westerly portion of
the bridge was totally damaged by fire which was
set by embers blown from the still smoldering,
burned-over area only 20 feet from its west end.
(4) There was one steel bridge with a wooden
deck (Bridge 37) located within the burned-over
area. This bridge was undamaged by fire.
(5) There were two street railway Bridges (13
and 44) and two railroad Bridges (9 and 26) of
steel construction with wooden ties, within, or
adjacent to, the burned-over area. Bridges 13 and
44 sustained no fire damage, whereas Bridge 26 sus-
tained slight flash-burn damage. It was reported
that several freight cars burned on Bridge 9 as a
result of direct ignition of the cars or their contents
by radiated heat from the atomic bomb. Only a
few wooden ties were charred and it is possible that
they were burned by hot coals dropped previously
by locomotives. On Bridges 9 and 26, red paint on
the side of steel girders which faced AZ was dis-
colored by radiated heat. Steel bridges were other-
wise undamaged by fire.
42
(6) Conerete bridges sustained absolutely no
fire damage.
7. Recapitulation and Summation of Bridge
Damage. The damage resulting from many
causes and occurring at different times had left a
damage analysis problem of considerable com-
plexity at Hiroshima. The cause and extent of
damage to the bridge system by the atomic bomb
has been segregated. from other damage and is
summarized in Table 4.
j. Samples and Laboratory Testing of Mate-
Samples of two cast-iron, railing-post sec-
tions from Bridges 23 and 24 (Sample D) and also
paint samples from Bridges 26 and 27 (Sample B)
were secured for tests by the Bureau of Standards
as follows:
rials,
Sample B. Paint samples from Bridges 26 and 27.
(1) Chemieal analysis and comparison of sam-
ples exposed and unexposed to bomb effects.
(2) Opinion as to agencies causing change, if
any, in composition.
Sample D. Two cast-iron, railing-post sections.
(1) Determine tensile, compressive, and shear
strengths.
(2) Test for hardness.
(3) Metallurgical analysis.
To date results have been received on Sample D
only: “Sample D, 7wo Cast-Iron, Railing-Post
These were identified as being one from
Bridge 23, and one from Bridge 24. Specimens
for tension, compression, and torsion tests were
machined from each section and tested. The re-
sults, together with the hardness numbers and
chemical composition, follow :
Sections.
Bridge 24
Bridge 2%
Sample:
Tensile strength, Ib/in 2? 19, 700 22, 700
Compressive strength, lb/in ? 72, 200 69, 100
Modulus of rupture for torsion,
Ib/in 2. 26, 500 27, 300
Rockwell indentations num-
ber : B80- B90 -B75-BS85
Chemical composition:
C, percent 3. 67 3. 71
Mn, pereent. —__- . 29 22
P, pereent__ 17 . 14
5, percent . 13 | _11
Si, pereent_- 1. 35 | 1, 26
* Pounds per square ineh, '
ASTM Spee. A48-41 for Gray Tron Castings
classifies cast irons by minimum tensile strength.
These rails correspond to Class 20, the classifica-
tion of lowest tensile strength. Spec. A48—-41 does
not provide for compression or torsion strengths,
nor for chemical analysis. However, the relation-
ships among the tensile, compressive, and shearing
strengths are about the same as in domestic cast
irons of this class, and the carbon content is perhaps
somewhat higher, and the silicon and manganese
contents considerably lower than in most compar-
able cast irons.”
4. Recommendations and Conclusions
a. The Bridge System. ‘The bridge system was
satisfactory and adequate to accommodate the serv-
ice, utility, communication, and transportation sys-
tems of Hiroshima. The bridges were conveniently
located for efficient travel between islands and
mainland. Certain bridges were essential for car-
rying services and utility lines across the several
branches of the Ota River to the many districts
of the city. Neglect in planning to provide pro-
tection for approaches and ends from flimsy,
wooden buildings, rather than any direct physical
damage from the atomic bomb, deprived the in-
habitants of their use after the attack until relief
parties cleared away the debris from fire and blast.
b. Design, Construction Features, Materials and
Loading. Yn general, design, details, and arrange-
ments for timber, concrete, and steel bridges ap-
peared to be below United States standards except
for the steel-plate girder bridges for railroads and
steel-truss aqueducts which compared favorably
with similar structures in the United States, In
size and appearance the steel employed in bridge
structures was comparable with United States
standards; otherwise, the quality of materials ap-
peared to be below that used in the United States
for similar structures. Generally the bridges were
designed to carry lower loadings than American
types.
c. Timber Bridges. The timber bridges (1,450
to 9,800 feet from GZ) generally were of poor con-
struction by American standards. They con-
sisted of many spans of log girders simply sup-
ported on multilog-pile bents. Although they
were simple in design, low in cost, rapidly and eas-
ily erected and repaired, and built of material
which was relatively plentiful, they were not
sturdy, and fire and blast easily destroyed them,
Data indicated that the timber bridges were vul-
nerable and were less resistant to the atomic bomb
than conerete and steel. Based on four bridges,
using the average circle of damage method, the
mean area of effectiveness of the bomb in causing
73156847 4
structural damage by blast to timber pile bridges
was 2.4 square miles with a mean effective radius
of 4,600 feet.
d. Steel Bridges (260 to 7,600 feet from GZ)
were either of built-up, plate-girder sections or
standard, rolled-steel sections. Analysis of the
data showed the amount of structural damage to
steel bridges caused by bomb effects to be relatively
small. One bridge (a pin-connected steel truss)
was, however, totally damaged by blast. This
was a very old bridge about 1,190 feet from GZ
and because of its design and age, was an easy
victim of the atomie bomb, Although three of the
steel bridges were within 1,000 feet of GZ they
suffered little or no structural damage. The su-
* perticial and minor damage to them was confined
43
largely to the reinforced-concrete decks, side-
walks, railings and ornamental features. There
was no evidence which would point to high tem-
peratures as the cause of damage. Several
bridges, however, located from 4.360 to 6,580 feet
from GZ, were affected by radiant heat to an ex-
tent which caused discoloring of the old paint on
the steel members facing the direction of the flash.
It is concluded that all damage to steel bridges
was caused by blast. The mean area of effective-
ness of the atomic bomb dropped at Hiroshima was
zero for causing structural damage to steel-girder
bridges similar to those included in this study.
The pin-connected truss bridge totally damaged
by blast at 1,190 feet from GZ was judged to be
unreliable as a source of data for conclusions on
resistance to the bomb.
e. Reinforced-Concrete Bridges (A930 to 12.200
feet from GZ) showed a striking lack of uni-
formity in design and in quality of materials. A
few whose superstructures were supported on
concrete piers appeared more massive than similar
structures in the United States. Other concrete
bridges, generally supported on concrete bents,
were estimated to be below United States stand-
ards in design loads. The nearest concrete bridge
to GZ (1,930 feet) was Bridge 30 which suffered
severe flood damage subsequent to the atomic-
bomb attack. Insofar as could be determined by
interrogation and post-attack air cover, however,
the bridge was open to highway traflic after the
attack and was not structurally damaged, although
possibly weakened by the atomic bomb. There-
fore, the only specific evidence of damage to con-
crete bridges was the superficial damage from
blast to 5 bridges, 4,270 to 6450 feet from GZ.
Thus, from an analysis of data, it is concluded that
reinforced-concrete bridges were the most effective
of all types in withstanding the effects of the
atomic bomb. This conclusion is consistent with
that of the Building Damage Section of this report
which found that “multistory, earthquake-resist-
ant, reinforced-concrete buildings located near the
zero point suffered moderate to negligible struc-
tural damage.” Since the bridges were normally
designed to withstand heavier loads than the
buildings, and some were earthquake resistant, it
is improbable that they would have been structur-
ally damaged even though located nearer GZ.
Accordingly it is concluded that for the atomic
bomb and height of burst employed at Hiroshima
the MAE was zero for causing structural damage
to reinforced-concrete girder bridges.
f. Damage Features. Wt was believed that
damage to ornamental features (posts, caps, cop-
ings, curbs, and railings), with the possible ex-
ception of those bridges within 1,000 feet of GZ,
was due largely to inferior design. These par-
ticular parts of the bridges were those most. se-
verely damaged by blast.
g. Different degrees of blast damage caused to
bridge railings and ornamental features appeared
in regular concentric areas around GZ. This regu-
lar pattern of damage was due to the absence of
topographical obstructions which might have pro-
tected any particular areas from the blast. At
long distances, where the blast was traveling in an
almost horizontal direction, damage was inflicted
principally on railings facing the flash. Buildings
adjacent to bridges, however, provided some
shielding for the structures, especially for orna-
mental features,
h. It was assumed that forces initially origi-
nated at AZ were shock forces radiating from that
point. This assumption was strengthened by the
positions of the railings of Bridge 23, 860 feet from
GZ, which fell toward the point of detonation of
the bomb. This indicated that these positive forces
44
probably weakened the railings, and negative
forces (toward GZ) lasting over a longer period
of time completed the collapse. The negative
phase, although probably much less powerful than
the positive phase, was credited with causing the
railings to fall toward GZ.
7. It was further concluded that if the sidewalks,
decks, and railings had been strongly anchored to
the structural members, the damage would have
been greatly decreased, On the other hand, it was
recognized that the “floating” decks, if exposed to
a more powerful blast weapon, might decrease
structural damage to beams and girders by reduc-
ing the loads from blast, especially from blast
forces reflected onto the underside of the deck. It
is evident that. if the concrete deck were boxed
around the steel members, as in American practice,
powerful enough forces would lift the slabs and
steel members as a unit with the probability of
severe structural damage. It is recommended
therefore that deck structures be simply supported
on steel members, and designed: only to transmit
downward loads to the structural beams and
girders.
j. Since destruction caused by the atomic bomb
was largely associated with fire, comparatively lit-
tle structural damage was caused to the noncom-
bustible targets such as steel and concrete bridges.
No evidence was found of spalled concrete or
oxidized steel which would point to fire as the cause
of damage.
kk. Had the atomic bomb been released closer to
GZ, the results of the intense heat and increased
pressure would probably have been more destruc-
tive to those bridges located within 1,000 feet
of GZ,
1. The relatively small amount of structural
damage inflicted on the noninflammable bridges
studied indicated that in order to destroy such
structures higher temperatures and more powerful
forces must be developed.
Tasie 4.—Recapitulation of bridge damage
‘Timber bridges Concrete bridges Steel bridges
Damage Area Area Area Remarks
Number toa Percent Number eae Percent Number ae Percent
feet) feet) feet)
Structure, blast________ 1 1, 940 20 0 0 0 4 8, 165 20
Superficial, blast_______ 0 0 0 5 0 0 5 0 0 | Brokenrailings, curbs,
copings, and dis-
lodged members.
Blast. 5262 eee da LU) eS a (Ee) AP ee | ee ee ee
Mixed: 22. hee eee 3 100 0 0 0 0 0 0
Vive == 5 ee eee TPO ie ber te Ie) (eee | eet >| (le ve Z oa
Done ban ee 5 | 19, 720 66 0 0 0 0 0
Total damaged 9 | 39, 100 68 5 0 0 9 8, 165 8
area.
SUMMATION
Total area of damaged 9 | 57, 130 48 5 | 54, 570 42 9 | 98, 340 47
bridges.
Total area of undam- 10 62,010 52 10 74, 640 58 14 /|112, 410 53
aged bridges.*
Wolaleeercatas 19 119,140 | 100) 15 129,210 | 100 28 210,750 100
Percent damaged of |_____.|_-____- 33 | Lae
total area.
« Lee gt are nine timber, seven concrete, and three steel bridges which were damaged by either flood or typhoon, or both, on 17 Sept. and 4 Oct. 1945,
respectively.
45
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PHOTO 1-XII. Bridge 1. Looking west at east side of undamaged bridge over the Enko-Gawa,
Northeast corner of north abutment of undamaged bridge (9,800 feet to GZ,
10,000 feet to AZ).
PHOTO 2-XII. Bridge 1.
46
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PHOTO 3-XII. Bridge 2. East elevation of single-track, railroad bridge over the Enko-Gawa (8,480 feet to
GZ, 8,740 feet to AZ).
PHOTO 4-XII. Bridge 3. Looking west at flood-damaged, highway bridge over the Enko-Gawa. Water main
carried by bents (7,130 feet to GZ, 7,390 feet to AZ).
47
steel exposed at section of break in
ing
deck girder.
Reinfore
Bridge 3.
PHOTO 5-XII.
48
PHOTO 6-XII. Bridge 3. Damaged concrete girder.
PHOTO 7-XII._ Bridge 3. Steel reinforcement in concrete deck.
PHOTO 8-XII._ Bridge 4. North elevation of reinforced-conecrete bridge over the Enko-Gawa. Superficial
blast damage at northeast corner railing (6,450 feet to GZ, 6,750 feet to AZ).
50
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PHOTO 9-XII. Bridge 4. Southeast corner of cast abutment,
PHOTO 10-XII._ Bridge 5. Looking north at reinforced-concrete bridge over the Enko-Gawa. Note Bridge
5A (steel truss) north of Bridge 5 (6,210 feet to GZ, 6,510 feet to AZ) undamaged.
51
PHOTO 11-XII. Bridge 6. Looking south at remains of bridge over Enko-Gawa. Destroyed by blast
and fire (5,370 feet to GZ, 5,730 feet to AZ).
PHOTO 12-XII. Bridges 7 and 7A. Looking west between reinforced-conerete, undamaged highway
bridge and steel-truss aqueduct over the Kyobashi-Gawa (5,200 feet to GZ, 5,570 feet to AZ).
52
PHOTO 13-XII. Bridge 8. South elevation of bridge over Kyobashi-Gawa.
Superficial blast damage to
concrete railings (5,390 feet to GZ, 5,700 feet to AZ).
PHOTO 14-XII. Bridge 8A.
Looking north at undamaged, steel, I-beam railroad bridge (5,580 feet t
GZ, 5,900 to AZ).
Oo
53
PHOTO 15-XII. Bridge 9. South elevation of undamaged, double-track railroad bridge over the Kyobashi-Gawa.
PHOTO 16-XIJ. Bridge 9. Paint on south elevation of steel girders discolored by exposure to bomb effects
(5,730 feet to GZ, 6,050 feet to AZ).
54
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PHOTO 17-XII._ Bridge 9. Paint on north elevation of steel girders unaffected by bomb.
PHOTO 18-XII. Bridge 10, East elevation of bridge over Kyobashi-Gawa showing flood damage (6,950
feet to GZ, 7,250 feet to AZ).
55
PHOTO 19-XII. Bridge 11. Looking southwest at corner of north abutment (7,960 feet to GZ, 8,200 feet to AZ).
56
PHOTO 20-XII. Bridge 11. Cable-tied vertical member of west suspension cable.
57
PHOTO 21-XII. Bridge 11. Looking west at east suspension cables of undamaged bridge over the
Kyobashi-Gawa (7,960 feet to GZ, 8,200 feet to AZ).
58
PHOTO 22-XII. Bridge 11, Underside of deck structure,
73156847 5 59
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PHOTO 23-NXII.
PHOTO 24-XII. Bridge 12.
Bridge.
Cable-tied vertical member of west suspension cable,
ae
South elevation of bridge over Kyobashi-Gawa (4,700 feet to GZ, 5,100
feet to AZ),
60
PHOTO 25-XII. Bridge 12, Ornamental stone post at southwest corner dislodged by blast (4,700 feet to
GZ, 5,100 feet to AZ).
61
PHOTO 26-XII. Bridge 12. Ornamental stone post at southeast corner dislodged by blast (4,700 feet to
GZ, 5,100 feet to AZ).
62
PHOTO 27-XII._ Bridge 13. Timber cribbing under trolley tracks at fourth span from east abutment of blast-and
flood-damaged bridge over the Kyobashi-Gawa (4,670 feet to GZ, 5,080 feet to AZ).
63
PHOTO 28-XII. Bridge 13. Looking west at cribbing under trolley tracks at fifth span from east abutment,
64
PHOTO 29-XII. Bridge 13. South elevation of trolley bridge.
PHOTO 30-XII. Bridge 13. Flood and blast damage (4,670 feet to GZ, 5,080 feet to AZ) north elevation.
65
PHOTO 31-XII. Bridge 13—-A. Looking east at totally damaged timber bridge by blast and fire over the
IXyobashi-Gawa.
PHOTO 32-XII. Bridge 13-A. Totally damaged by blast and fire (4,670 feet to GZ, 5,080 feet to AZ.)
66
ein or MB nore ee hb .. 6
PHOTO 33-XII. Bridge 14. West abutment of bridge over the Kyobashi-Gawa, totally damaged by fire
(4,760 feet to GZ, 5,170 feet to AZ).
PHOTO 34-XII. Bridge 15. Looking south at undamaged bridge over the Kyobashi-Gawa (5,580 feet
to GZ, 5,900 feet to AZ).
67
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PHOTO 35-XIIl. Bridge 16. North elevation of undamaged, reinforced-concrete, highway bridge over
the Kyobashi-Gawa (5,750 feet to GZ, 6,100 feet to AZ).
pAbbbbbaad, TELL °?
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PHOTO 36-XII. Bridge 17. Looking south at street railway and highway plate-girder bridge over the
Kyobashi-Gawa. Superficial blast damage to railings (7,600 feet to GZ, 8,870 feet to AZ).
68
PHOTO 37-XI1. Bridge 18. Undamaged highway bridge over the Motoyasu-Gawa (6,000 feet to GZ, 6,300
feet to AZ).
we
PHOTO 38-XII. Bridge 19. North elevation of highway bridge over the Motoyasu-Gawa. Ornamental
stone posts dislodged by blast (4,270 feet to GZ, 4,720 feet to AZ).
69
PHOTO 38A-XII. Pre-attack panoramic view of Hiroshima looking north, showing Bridges 19 and 20 in upper right
and 31 in upper left.
70
PHOTO 39-XII. Bridge 20. Looking south at slight blast damage to northwest area of bridge over the
Motoyasu-Gawa.
PHOTO 40-XII. Bridge 20. South elevation. Debris deposited against bents by flood (2,900 feet to
GZ, 3,450 feet to AZ).
71
PHOTO 41-XII. Bridge 20. Blast damage to north railing. Note flash burn on asphalt surface of bridge
deck (2,900 feet to GZ, 3,450 feet to AZ).
—
PHOTO 42-XII. Bridge 21. Southwest part of bridge over the Motoyasu-Gawa totally damaged by blast and flood
(1,450 feet to GZ, 2,460 feet to AZ).
73
PHOTO 43-XII. Bridge 22. Pre-attack Japanese photo showing south elevation. Nearest bridge to
GZ, 260 feet.
PHOTO 43A-XII. Bridge 22. Superficial blast damage to bridge over the Motoyasu-Gawa (260 feet to
GZ, 2,020 feet to AZ).
74
PHOTO 44-XII. Bridge 22. North elevation. No structural damage.
PHOTO 45-NII. Bridge 22. Stone posts and railing damaged by blast (260 feet to GZ, 2,020 feet to AZ).
PHOTO 46-XII. Bridge 22. Blast damage and flash-burn to ornamental stone post (260 feet to GZ, 2,020
feet to AZ).
76
PHOTO 47-XII._ Bridge 23. Looking east at west elevation. Note cantilever span adjacent to Bridge
24, over the Ota-Gawa.
PHOTO 48-XII. Bridge 23. Cast-iron post sections and conerete railing sheared off east curb by blast
(860 feet to GZ, 2,170 feet to AZ),
77
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re
PHOTO 49-XII. Bridge 23. Cast-iron post sections and concrete railing along west curb damaged by blast
(860 feet to GZ, 2,170 feet to AZ).
78
PHOTO 50-XII. Bridge 24. North elevation of bridge over Ota-Gawa. Concrete walk and railing
damaged by blast.
PHOTO 51-XII. Bridge 24. Southeast part of bridge over Ota-Gawa. Railing damaged by blast
(1,000 feet to GZ, 2,230 feet to AZ).
79
PHOTO 52-XII. Bridge 24. Blast damage to southwest area. Conerete walk raised 20 inches above original road
grade. Granite curb moved 914 inches north from original position (1,000 feet to GZ, 2,230 feet to AZ).
80
PHOTO 53-XII. Bridge 24. North elevation adjacent to east abutment. No structural damage to steel-
plate girders.
81
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PHOTO 54-XII. Bridge 24. Portion of north granite curb and walk. Drain seupper west of Bridge 23,
elevated 20 inches above road grade by blast effects.
PHOTO 55-XII. Bridge 24. Portion of north granite curb and walk. Drain seupper east of Bridge 23,
elevated 24 inches above road grade by blast effects (1,000 feet to GZ, 2,230 feet to AZ).
82
PHOTO 56-XII. Bridge 24. North conerete walk pushed by blast effects 38 inches above cross-steel members sup-
porting the north walk (1,000 feet to GZ, 2,230 feet to AZ).
83
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PHOTO 57-XII. Bridge 24. Blast effects moved roadway slab laterally 15 inches north and raised it 14 inches above
original position. Note pushed-up scupper (1,000 feet to GZ, 2,230 feet to AZ).
84
PHOTO 58-XII. Bridge 24. Northwest corner of bridge showing blast damage to concrete walk, granite
curb and roadway concrete deck.
PHOTO 59-XII. Bridge 24. Northeast corner of bridge showing blast damage to concrete walk and
granite curb (1,000 feet to GZ, 2,230 feet to AZ).
85
PHOTO 60-XII. Bridge 24. Intersection of Bridges 23 and 24. Rails of south railway tracks pushed
up 8 inches above original road grade by blast.
PHOTO 61-XII. Bridge 24. Blast-damaged, cast-iron post sections at northwest corner of intersection
of Bridges 23 and 24. Post sections 5 feet on centers for concrete railings of Bridge 23, and 6 feet on centers
for Bridge 24 (1,000 feet to GZ, 2,230 feet to AZ).
86 ,
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PHOTO 62-XIIL.
PHOTO 63—XII.
Bridge 24. Northeast corner of steel-plate girder. No structural damage by blast,
Bridge 24. Underside of steel-plate girders and cross-members of west abutment.
No structural damage (1,000 feet to GZ, 2,230 feet to AZ).
87
PHOTO 64-XII.
Bridge 24. Underside of steel-plate girders and cross-members at west abutment. No structural
damage.
PHOTO 65-XII. Bridge 24. Secondary framing of exterior girder under north walk at approximate bridge center.
No structural damage.
89
PHOTO 66-XII. Bridge 24. Inside faces of plate girders, fourth span from east abutment under north walk. De-
flected slightly by blast (1,000 feet to GZ, 2,230 feet to AZ).
90
PHOTO 67—XII. Bridge 24. Inside faces of plate girders, fifth span from east abutment under north walk. Defleeted
slightly by blast (1,000 feet to GZ, 2,230 feet to AZ).
731568—A7 7 91
PHOTO 68-XII. Bridge 24. East end of bridge. Slight deflection in trolley rails due to shifting of
< bridge deck by blast.
PHOTO 69-XII. Bridge 24. West end of bridge. Streetcar rails moved laterally 15 inches to the
north when blast effects shifted bridge deck (1,000 feet to GZ, 2,230 feet to AZ).
PHOTO 70-XII. Intersection of Bridge 23 (left) and Bridge 24 (right). All damage from blast effects. Bridge 23 (860
feet to GZ, 2,170 feet to AZ). Bridge 24 (1,000 feet to GZ, 2,230 feet to AZ).
93
; PHOTO 7I-XI. Bridge 25. West elevation of bridge over Ota-Gawa. Flood damage and superficial
damage to concrete coping by blast (5,200 feet to GZ, 5,570 feet to AZ).
PHOTO 72-XII. Bridge 26. South elevation of undamaged, double-track railroad bridge over Ota-Gawa
(5,750 feet to GZ, 6,100 feet to AZ).
94
oS
PHOTO 73-XII. Bridge 26.
Paint on the south elevation of girders discolored by exposure to
bemb effects.
ee
pi Bios
PHOTO 74-XII. Bridge 26. Paint on the north elevation of girders unaffected by bomb effects
(5,750 feet to GZ, 6,100 feet to AZ).
95
PHOTO 75-XII. Bridge 27. West elevation of undamaged bridge over the Temma-Gawa. Paint on the
members of the east elevation were discolored by exposure to bomb effects. Steel members of west
elevation were only slightly discolored (4,360 feet to GZ, 4,790 feet to AZ).
‘
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PHOTO 76-XII. Bridge 28. Remains at north abutment of bridge over the Temma-Gawa. Totally
damaged by flood (4,480 feet to GZ, 4,840 feet to AZ).
96
PHOTO 77-X1II.
PHOTO 78-XII.
Bridge 29.
Bridge 29.
Looking north at remains of bridge over the Ota-Gawa. Totally damaged by blast.
Southwest corner.
Totally damaged by blast (1,190 feet to GZ, 2,310 feet to AZ).
97
PHOTO 79-XII. Bridge 29, Kast abutment. Bridge totally damaged by blast (1,190 feet to GZ, 2,310 feet to AZ).
98
we. is 6
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> Os lg 9 ] ooking east at debri at west abutment 1,19 fy my eet to A hi).
99
PHOTO 81-—XII. Bridge 30. Looking north at flood damage to highway bridge over the Ota-Gawa.
(Note Bridge 30—A, aqueduct.)
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PHOTO 82-XII. Bridge 30. Fractured roadway deck and longitudinal beams. Note reinforcing steel
and construction joint at junction of beams and slab.
100
PHOTO 83-XII. Bridge 30. Steel reinforeement in fractured con-
crete girder.
101
PHOTO 84-XII. Bridge 30. Fractured roadway deck and girder. Note reinforeing steel.
102
PHOTO 85-XII. Bridge 30-A. North elevation of aqueduct for 16-inch main over the Ota-Gawa.
Slightly damaged by blast.
PHOTO 86-XIT. Bridge 30-A. Looking northeast at corner of west abutment. Steel truss slightly
damaged by blast. Note damaged covering of 16-inch water main (1,880 feet to GZ, 2,750 feet to AZ).
103
PHOTO 87-XII. Bridge 31. Looking south at flood-damaged, highway bridge over the Ota-Gawa.
Sixteen-inch water main carried by bents. Top portion of northwest corner post dislodged by blast
(4,570 feet to GZ, 5,000 feet to AZ).
PHOTO 88-XII. Bridge 32. Looking north at flood-damaged highway bridge over the Temma-Gawa
(9,400 feet to GZ, 9,600 feet to AZ).
104
PHOTO 89-XII. sridge 33. Looking west at flood-damaged bridge over the Temma-Gawa. Sixteen-inch
water main carried by bents (5,300 feet to GZ, 5,650 feet to AZ).
PHOTO 90-XII. Bridge 34. Looking west at timber bridge over the Temma-Gawa. Total damage by
fire (3,700 feet to GZ, 4,200 feet to AZ).
105
PHOTO 91-XII. Bridge 35. Looking north at east abutment of bridge over the Temma-Gawa. Totally
damaged by flood.
PHOTO 92-XII. Bridge 35. West abutment of trolley bridge. Totally damaged by flood (3,190 feet to
GZ, 3,750 feet to AZ).
106
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PHOTO 93-XII. Bridge 36. East and west abutment of bridge over the Temma-Gawa, Totally damaged
by flood (3,200 feet to GZ, 3,760 feet to AZ),
PHOTO 94-XII. Bridge 37. Looking north at plate girder, wooden-deck, highway bridge over the
Temma-Gawa. Westerly portion severely damaged by flood. Sixteen-inch water line carried by brackets
along south side (3,220 feet to GZ, 3,770 feet to AZ).
731568—47 s 107
PHOTO 95-XII._ Bridge 38. Looking west at remains of timber bridge over the Temma-Gawa. Severely
damaged by fire (west half) and later totally damaged by flood (3,750 feet to GZ, 4,250 feet to AZ).
PHOTO 96-XII. Bridge 39. Looking northwest at remains of timber bridge over the Temma-Gawa.
Severely damaged by fire (easterly 4) and later totally damaged by flood (3,880 feet to GZ, 4,390 feet to AZ).
PHOTO 97-XII. Bridge 40. Looking west at bridge over the Fukushima-Gawa. Northerly portion severely
damaged by fire (5,360 feet to GZ, 5,700 feet to AZ).
PHOTO 98-XII. Bridge 41. Looking west at undamaged concrete bridge over canal connecting the Yamate-
Gawa and the Fukushima-Gawa (6,150 feet to GZ, 6,460 feet to AZ).
109
PHOTO 99-XII. Bridge 42. Looking west at remains of timber bridge over the Fukushima-Gawa
Totally damaged by flood (5,100 feet to GZ, 5,490 feet to AZ).
PHOTO 100-XII. Bridge 43. North elevation of newly constructed timber bridge over the Fukushima-
Gawa, Old bridge was totally damaged by blast and fire (5,180 feet to GZ, 5,510 feet to AZ).
110
PHOTO 101-XII. Bridge 44. Southeast part of undamaged, street railway bridge over the Fukushima-
Gawa (5,300 feet to GZ, 5,650 feet to AZ).
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PHOTO 102-XII. Bridge 45. Looking northwest at the southeast area of the concrete highway bridge
over the Fukushima-Gawa. Moderately damaged by flood (7,010 feet to GZ, 7,010 feet to AZ).
111
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PHOTO 103-XII. Bridge 46. Looking west at remains of timber bridge over the Yamate-Gawa. Totally
damaged by flood (8,090 feet to GZ, 8,350 feet to AZ).
PHOTO 104—-XII. Bridge 47. Looking north at undamaged trolley bridge over the Yamate-Gawa (7,450
feet to GZ, 7,700 feet to AZ).
112
PHOTO 105-XII. Bridge 48. Looking north at undamaged plate-girder, concrete-deck, highway bridge
over the Yamate-Gawa; 12- and 14-inch water mains are carried by steel saddles between girders (7,130
feet to GZ, 7,400 feet to AZ).
PHOTO 106—-XII. Bridge 49. Looking northwest at remains of timber foot bridge over the Yamate-Gawa.
Totally damaged by flood (6,380 feet to GZ, 6,650 feet to AZ).
113
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PHOTO 107—XII. Bridge 50. South elevation of undamaged, plate-girder railroad bridge over the
Yamate-Gawa. Paint on girders on the south elevation was slightly discolored by exposure to bomb effects.
North elevation unaffected (6,580 feet to GZ, 6,900 feet to AZ).
PHOTO 108-XII. Bridge 51. South elevation of undamaged, plate-girder railroad bridge and underpass.
Paint on girders on the south elevation was slightly discolored by exposure to bomb effects. North
elevation was unaffected (6,450 feet to GZ, 6,780 feet to AZ).
114
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PHOTO 109-XII, Bridge 51. Cast metal sign fastened to the face of the north plate girder, showing Cooper E-40
loading, ete.
115
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PHOTO 110-XII. Bridge 52. General oblique view showing most remote bridge included in study (12,200 feet to GZ,
rr
12,450 feet to AZ)
116
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Distance to GZ = §390'
BRIDGE 8A
Distance to GZ = 5580
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Distance to GZ= 6950’
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276'-0"
74'- 0" Continuous Girder
33-0" “Spans At_ 30-0" 33'-0"
Hasse fritti({PIiritiij{ tiittirir || Satttir|(tittiriti Pi 111111 |
=a
15'-0" |
5 5 FREES. TES
SPRING SUPPORT AT
FIRST PIERS ONLY
HIGHWAY PEDESTRIAN HIGHWAY
TRAFFIC
DISTANCE TO GZ 4270'
PEDESTRIAN
TRAFFIC
DISTANCE TO GZ 2,900!
STIFFENER SKETCH
OF TYPICAL GIRDER
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
ft “
7 Sim 50-0" = 350'-0"
ELEVATION
Floor Beam Connection
AQUEDUCT
DISTANCE TO GZ |,880°
ELEVATION OF SIMPLE SPAN
baa NVA
SKETCH OF TOP BRACING |/2*'¥2*\4"E
3 2-3"<3"x 8"L V4"x2" Bors
OOO
x
SKETCH OF BOTTOM BRACING
Main Girder Connection
SUSPENDER BRACING
HIGHWAY PEDESTRIAN
TRAFFIC
DISTANCE TO GZ 4,370!
BRIDGE 27 BRIDGE 30-A
|
|
|
|
|
|
|
|
|
|
|
SECRET
ELEVATION
See Figure i7 For
Rail & Tie Detail
RAILROAD
DISTANCE TO GZ 5,750
2-6'x6"x/2" 1s
At Abutment Onl
SKETCH OF LATERAL
BRACING BETWEEN GIRDERS
HIGHWAY TRAFFIC
DISTANCE TO GZ 4,570
SECRET BRIDGE 31
US. STRATEGIC BOMBING SURVEY
BRIDGE SKETCHES
HIROSHIMA, JAPAN
TRANSVERSE SECTION
FIGURE 4-X0
731568 O - 47 (Face p. 116) No. 4
nes. REET
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BRIDGE 44
DOUBLE TRACK TROLLEY STRUCTURE SIMILAR TO BRIDGE 13.
14 SPANS AT 34’ LENGTH= 476:
WIDTH= 16!
8 7°X24" |-BEAM GIRDERS.
DISTANCE TO G Z = 5300’.
BRIDGE 45
HIGHWAY & PEDESTRIAN TRAFFIC STRUCTURE SIMILAR TO BRIDGE 33.
12 SPANS AT 36'. LENGTH= 432°.
WIDTH= I9'
5 2I"XI3" HAUNCHED R.C. GIRDERS. 2~SPAN CONTINUOUS.
DISTANCE TO G Z=70I0'.
BRIDGE 47
DOUBLE TRACK TROLLEY STRUCTURE SIMILAR TO BRIDGE 13.
10 SPANS AT 34". LENGTH= 340!
WIDTH =16',
8 7°X24" I-BEAM GIRDERS.
DISTANCE TO G z = 7450'
SEE PHOTO 104.
I" PLATE
DISTANCE TO GZ =5300' |
ee
ik §
BRIDGE 35
DOUBLE TRACK TROLLEY STRUCTURE SIMILAR TO BRIDGE 13.
8 SPANS AT 33'. LENGTH= 264".
WIDTH= 16.
8 7°X24" |-BEAM GIRDERS.
DISTANCE TO G.Z.= 3190".
ELEVATION
12'-o"
HIGHWAY & PEDESTRIAN
BRIDGE
HIGHWAY & PEDESTRIAN
BRIDGE
BRIDGE 37
en ee
4" WOODEN . |
DISTANCE TO GZ =3220' =
i | — —— — —— ft
BRIDGE 33
LONGITUDINAL VIEW
FOR RAIL & TIE DETAIL, SEE BRIDGE 9-FIGURE 7
IY ma TereeT dr Tt
LONGITUDINAL VIEW ae a
ELEVATION
TRANSVERSE SECTION.
SIMILAR TO BRIDGE 9-FIGURE I7.
GIRDER: 13"X 1/2" COVER PLATE
4°X 6" X 1/2" FLANGE ANGLES
4°X4"X 3/8" STIFFENER ANGLES, EX-
| CEPT 4"X6"X /2"ANGLES AT EVERY
(on nr oto to | oh,
go
ELEVATION
4TH STIFFENER
3 /2"X 3 1/2"X 3/8" LATERAL & SWAY
BRACING ANGLES. LATERAL BRAC-
ING ATEVERY 4TH STIFFENER
3/8" 12" COVER PLATE vet:
6"X6"X 1/2"FLANGE ANGLES
4"X 4"X 3/8" STIFFENER ANGLES
42"x 1/2" WEB PLATE DOUBLE TRACK RR
BRIDGE
SI HIGHWAY 8 PEDESTRIAN BRIDGE 50
—_ ee eee BRIDGE 48 DISTANCE TO 6 Z = 6580"
DISTANCE TO GZ = 7130°
TRANSVERSE SECTION
HIGHWAY & PEDESTRIAN
BRIDGE
BRIDGE 41
DISTANCE TO GZ =6150'
aS ZZ
GENERAL NOTES
|. FOR BRIDGE 13, SEE FIGURE /8.
2. IN MANY CASES, DIMENSIONS & SIZES
SHOWN ARE APPROXIMATE, DUE TO
STRUCTURAL DAMAGE.
U.S. STRATEGIC BOMBING SURVEY
BRIDGE SKETCHES
HIROSHIMA, JAPAN
FIGURE 5-XI
731568 O - 47 (Face p, 116) No. 5
|
.
i ‘ > 6 oe eh a oe
+ = wes, +p RVRAPE Peegrg ha
rt A a jr ait e533 aa
dua" BT we
SECRET
BRIDGE 51
DOUBLE TRACK R.R. STRUCTURE SIMILAR TO BRIDGE9, FIGURE 17 ,& BRIDGE 50, FIGURE 5.
2 SPANS AT 33: LENGTH= 66!
2PLATE GIRDERS- 36" 8 48" IN DEPTH.
GIRDER: 13"X 1/2" COVER PLATE.
3/8" WEB PLATE.
4"X 4"X 3/8" STIFFENER ANGLES.
BRACING SIMILAR TO BRIDGE 50,FIGURE 5.
DISTANCE TO GZ =6450'
9-6" CANTILEVER 9'-6" CANTILEVER
Pee 1 (a ae a
HIGHWAY & PEDESTRIAN
TRAFFIC
BRIDGE 52
DISTANCE TO G Z =12200'
SECRET
BRIDGE SKETCHES
HIROSHIMA, JAPAN
FIGURE 6~-XIT
TRANSVERSE SECTION
117
DATA
GENERAL NOTES
(a) Plan distance is the distance from the
center of bridge to GZ.
(6) Slant distance is the distance from the center
of bridge to AZ.
BRIDGE 1
Coordinates; 5K
Over River: Enko-Gawa.
Distance from “Zero Point”: Plan, 9,8005 slant,
10,000.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Seven timber beams,
12 by 22 inches per span.
Decking: Timber, 4 by 10 inches.
Abutments: Stone masonry.
Piers: Four piles (12-inch diameter) bent of
concrete footings.
SPECIAL FEATURES: Used stapled connec-
tions rather than steel bolt.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards. Generally, the bridges were
designed to carry lower loadings than is Ameri-
can practice.
QUALITY OF CONSTRUCTION AND MATE-
RIALS: The design, details and arrangements
of the bridge structure were below United States
standards. Quality of materials fair.
DAMAGE—EXTENT: None:
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Bridge being used but timber deck-
ing decaying.
PHOTOGRAPHS:
No,
1
TO PLACE IN
Direction and title
Looking west at east side of undamaged
bridge over the Enko-Gawa.
SHEETS
118
PHOTOGRAPHS—Continued
No.
”
Direction and title
Northeast corner of abutment of undam-
aged bridge.
BRIDGE 2
Coordinates: 5J
Over River: Enko-Gawa.
Distance from “Zero Point”: Plan, S480; slant,
8,740.
USE: Railroad.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: 38 inches in depth.
in depth.
Decking: Ties and rails.
Abutments: Stones,
Piers: Concrete.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridges woulc
earry normal railroad loadings. Comparabl:
with similar structures in United States.
QUALITY OF CONSTRUCTION AND MA.
TERIALS: Comparable with similar struc
tures in United States. Concrete and masonry
good.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All,
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a single-track railroad.
PHOTOGRAPHS:
TO PLACE IN
No. Direction and title
3 East elevation of single-track railroad
bridge over the Enko-Gawa. Undam-
aged.
BRIDGE 3
5 ed
Coordinates:
Over River: Enko-Gawa.
Distance from “Zero Point”: Plan, 7,130; slant,
7,390.
Foundation
TYPICAL EARTHQUAKE DESIGN
ig i greta AG EE SKETCH SHOWING TYPICAL REINFORGING STEEL
Overturning force for girders= 15% of dead load.
Bors vary in size from 1/4" to | 78"
Deformed bars were not used.
Only smooth round bors used.
TROLLEY CARS ES Rea TROLLEY BRIDGES
Showing Types “A” and “B” a girder ( |-Beams) spon lengths
an abutments.
: GENERAL NOTES
. For schedule of steel material.
a All materials of medium steel unless otherwise
specified.
TYPICAL FLOATING PIER 30" 330", 330 0") 3340 All rivets of rivet steel and 3/4" diameter
% unless otherwise noted.
Bye All rivet holes punched 1/8" less and reamed
V6" greater diameter than that of rivet.
er Wheel
25 T.
NOTES:
Sand added for additional weight and economy.
Dimensions are only approximate.
10.62' 8.50' 10.62"
3s : iw 478' 1"
ant ry
=F : BRIDGE 44
33 I: 0") 36‘0", 360",
SECRET
BRIDGES- DESIGN FEATURES
TYPICAL TROLLEY CARS AND BRIDGES BRIDGE 47 rae te
731568 O - 47 (Face p. 118) No. 1
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CORNER POST SKETCH
BRIDGE 12
TYPE - Steel Plate Girder
REMARKS:
SE and SW corner posts separated from railing:
Tops of NE and SE corner posts dislodged.
Top of NW corner post partly damaged.
Photos 24,25 and 26.
RAILING SKETCH
BRIDGE 25
TYPE ~ Reinforced Concrete
REMARKS :
NE and SW corner post tops blown off.
SE corner post top displaced 4”.
NW corner post top not disturbed.
Cancrete railing posts over each pier broken
south and north railings
Coping blown off both south and north railing
Photo 7!
on both
| TYPE- Reinforced Concrete
| REMARK
6Z-4270°
GRID 6G
CORNER POST SKETCH
BRIDGE !9
TYPE-Reinforced Concrete
REMARKS :
NE corner post cap blown entirely off.
NW,SE,and SW corner post caps moved 4" to 6" from
original position.
Railing 3' above road grade was not disturbed.
Photo 38
6Z-1190'
GRID 5G
Part blown off
ORNAMENTAL LIGHT POST
BRIDGE 29
TYPE - Pinned Steel Truss
REMARKS :
NE,SE, and SW ornamental cast iron light posts
entirely dislodged.
Upper portion of NW corner light post sheared off os
shown and blown 50’ SW from original position.
Photo 78.
————_
BRIDGE 4
Porhon of concrete roiling ct NE comer of bridge blown off.
Dist
6Z-2900'
GRID 6G
Pe post sheored off.
:
RAILING SKETCH
BRIDGE 20
24
Rood
TYPE - Steel 1 Beam
REMARKS :
Numerous railing posts connected to slab by cast iron
rods sheared off.
Roadwoy showed shadow marks of north railing.
Tin protective covering of I8" water main on north side
slightly effected by blast.
Photos 39,40, and 41.
CORNER POST SKETCH
BRIDGE 31
TYPE- Reinforced Concrete
REMARKS :
Top portion of NW corner post dislodged 3” to south.
Other posts not damaged.
Concrete railings not damaged.
Photo 87
BRIDGE 8
TYPE- Reinforced Concrete
REMARKS «
Concrete railings along both elevations of bridge blown off.
Distenae to Lg = §390'
tC)
SECRET 62-260"
CORNER POST SKETCH
BRIDGE 22
TYPE - Steel Pilate Girder
REMARKS :
All stone posts dislodged to some extent. at road grade.
NW corner post entirely blown down.
Upper sections of the four center posts were moved 2”
to 5" from original position.
Railings entirely destroyed.
Photos 43 to 46 inclusive.
RAILING SKETCH
BRIDGE I7
TYPE ~- Steel Plate Girder
REMARKS
Stone posts not damaged.
Railings of spans adjacent to east and west abutments were
not disturbed.
All other railings blown off.
Photo 36 SECRET
U.S. STRATEGIC BOMBING SURVEY
Superficial blest damage.| BRIDGES SPECIAL FEATURES
AND RAILINGS
731568 O - 47 (Face p. 118) No. 2
i
5
2-10" TYPICAL ELEVATION OF
TYPICAL SECTION GIRDER
OF RAILING
SECRET
SECTION A-A
TYPE A
12" Each Side Of Piers
8" Channel
j 31/2"x3 1/2"« 3/8"5
SECTION B-B
TYPE B
60" Each Side Of Piers
8" Channel |
II reo | II |
SECTION C-C
TYPE C
At Every Other Stiffener
Between Type B
NOTES
Reinforced concrete siobs are supported directly
by longitudinal steel girders. SECRET
Dimensions are only approximate. Many cases ‘
distances could not be measured accurately. Scale in Feet
In many cases thickness of slab could not be
determined. U.S. STRATEGIG BOMBING SURVEY
BRIDGE 22
HIROSHIMA, JAPAN GRID 5-H
FIGURE 9—XIT
731568 O - 47 (Face p. 118) No. 3
JUTE
[ ie ce ex y
= ea See me 5
a
Tidh 1
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a ORNS a
>tr a? pree
sacs . dire aa
| SECRET
HSESSoSSSeSiae EH asia “AREEEEE
FT
‘| Jel PLAN yt
REE eee
as EAST ELEVATION
—_e
Scale o12345f
BRIDGE 23
for all Details
ae or's HIROSHIMA, JAPAN GRID 4-H
FIGURE 10 —XIL
SECT. C-C
731568 O - 47 (Face p. 118) No. 4
“a4 ? bm
at tk
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fe R RAILING: 4 *:
a]
Beas Va Wig ig +
2 ig etad 2 7 Pte
“ 5
7 _ =H 2
=a wi RUBBLE RUBBLE Es RE Tile SNS Nee SE a —— fl
a eae ee RE. 5 METRE a EAST ABUT
———— Pas ees RSS PPE er I LE Da ————————|
alm |) Sa Se A | | (TRS SESS! | | 5 ES Ce eS 5 | (eS ee ae Se, fy Pence SST | me EM | 5
PLAN
SECTION SHOWING SLAB DAMAGE
ON NORTH SIDE BETWEEN FIRST & SECOND PIERS FROM WEST ABUTMENT
—— as
Ya"o-i2%0c 0 V2"d-12"0.6. ‘a"b-12" 06.
jo a4= ptr ret +
—+—{—1-}+ PB Bwe cw Bae
' TRANSVERSE RODS ednt DOWN OVER
roe SAME AS LONGITUDINAL
Af ORIDGE | 2.2
SECTION “A-A"
SIDEWALK SLAB
SKETCH OF BLAST REACTION DETAIL OF SCUPPER DAMAGE
ROADWAY SLAB TO BRIDGE STRUCTURE 9 “s
SECRET
REINFORCING DETAILS
—
BRIDGE 24
RAILING DETAIL
0 HIROSHIMA,JAPAN GRID 4-H
FIGURE |2—XIL
731568 O - 47 (Face p. 118) No. 6
. ig _ .
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ase UAWSOIF
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SECRET
560-0" Toto! th
ais LJ NOTES
— - Rid fe : Reinforced-concrete slab, supported directly by
hs reinforced concrete longitudinal girders.
f fe y No deck beams used as cross-members connecting
girders.
Dimensions ore only approximate. Many cases
distances could not be measured accurately.
In many cases thickness of slab could not be
determined.
[i]
/
/
/
/ /
/ /
/
/
7 /
/
/
Bey PLAN
Gontinuous Girder Continuous Girder ir Continuous Girder
i t
WEST ELEVATION
Scole for Plan, Elevation, & Section
|
2-4" 5" £0f Eoch Span
SECTION AA
ELEVATION
12’- 0”
3/8"8 Smooth 5"0.C. Long.
3/8"® Smooth 16" 0.C. Trans.
SECRET
ELEVATION OF GIRDER STIRRUP SLAB STEEL
a
0123 4 St. BRIDGE 25
HIROSHIMA, JAPAN GRID 3-H
FIGURE (3 —XIL
Scole for Girder Details
! 3 4
731568 O - 47 (Face p. 118) No. 7
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4-1"x4" Bors
2-1%4" Bars Latticed
12'-6"
i a tt
. : :
ie ie
CROSS SECTION
—————
das od
SECRET
NOTES
Wood deck supported directly by wooden stri
Wooden stringers ore supported directly by built plate
girder. (Transverse members)
Dimensions are only approximate. in many cases
distances could not be measured accurately.
ISOMETRIC - SHOWING DAMAGE
DAMAGE ‘ Bomb blast struck bridge from below
after rebounding from water and also
struck directly at sides causing failure in
members and bridge to fall downstream.
V2"x4" Lattice
SECRET
U.S. STRATEGIC BOMBING SURVEY
BRIDGE 29
HIROSHIMA, JAPAN GRID-5G
FIGURE 14 —XIL
731568 O - 47 (Face p. 118) No. 8
i ladhr i betinilider
! j fl
ible a
iw F saptaniinivt
PERIT EA TD hen epatan ls.
hit spetgily.i.
FEPPPEETTT AT Pe eye
’ tithe b esaceeig ae
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ee RRS
oe: cae . 5 F
ed y rue Stennett eee
be 0 x a ed hi oo. 7
va. cy ; A 8 ;
276'-0" Total Leng
3_Spons Continuous
ELEVATION
o123 4 Sft
ow
rg
io
i]
e-
r--
ST A SE
i
‘
NOTES
Reinforced- concrete sidb, supported directly by
reinforced concrete longitudinal girders.
No deck beams used as cross-members
connecting girders.
Dimensions are only approximate. Many cases
distances could not be measured
accurately.
SECTION CC
SECTION AA
0123 4 Sft.
EAST ELEVATION
SEGRET
U.S. STRATEGIC BOMBING SURVEY;
BRIDGE 3
HIROSHIMA, JAPAN ~~ GRID 5-J
FIGURE |S —XIL
731568 O - 47 (Face p. 118) No. 9
ror
est) fa eS tet
tt PETE eo At
EXPANSION JOINT
SUPPORT DETAIL
Sister
SECRET
NOTES
Reinforced -concrete slab supported directly by reinforced~-concrete,
longitudinal girders.
No deck beoms used as cross-members connecting girders.
Dimensions are only approximate. Mony coses distances
could not be measured accurately.
SECT. A-A SECT.B-B SECT. C-C STIRRUP
DETAIL
Expansion Joint
SECRET
US. STRATEGIC BOMBING SURVEY
BRIDGE 30
HIROSHIMA, JAPAN GRID-5G
FIGURE 16—XIL
731568 O - 47 (Face p. 118) No. 10
=a
—-—f" fe
i
oe
a ee SS
) y aye
onl p Divs ee
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3 SPANS AT 87'-0"
3 SPANS AT 57'-0"
| te -
s & oa BS es ‘ a ae 2 ee aaa
iio cl eerie ee | SSB See 2s) = . Sey
ee ————— = —— ———
LONGITUDINAL ELEVATION
5
100 LB. RAIL
FOR TI TS, SEE
Dera ie
8"xe"xX 9-O" TIES
18" 0.6.
13" 1/2" FLANGE PLATE
TRANSVERSE SECTION
“ A"- “ A
leo]
A
»
SS
a
i
z
SS
eZ
h —
1a ash
.
ELEVATION
DETAIL "A"
pe ut,
END ELEVATION
DETAIL OF SADDLES
|
CO)
FRONT ELEVATION
NOTES
DIMENSIONS ARE APPROXIMATE ONLY.
IN MANY CASES, DISTANCES COULD
NOT BE MEASURED ACCURATELY.
SECRET
-S. STRATEGIC BOMBING SURVEY
BRIDGE 9
HIROSHIMA, JAPAN GRID 3-1
FIGURE |7+XIL
731568 O - 47 (Face p. 118) No. 11
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3's3k3/8'Ls
ELEVATION ~ DETAIL
| a come
SECRET
NOTES
Dimensions shown are only approximate. In many cases
distances and thickness of steel members could not
be measured accurately.
US. STRATEGIC BOMBING SURVEY
BRIDGE 13
HIROSHIMA, JAPAN GRID-51
FIGURE |8-XIr
731568 O - 47 (Face p, 118) No. 12
‘ fay CTR RyRy es oe Lh
— ; £8 ‘iwininal qT siuatt
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16"X16'END POST
6" ree RAILING Acrentne el AE PosTs
12"x 22" GIRDER
16"X16" END BEARING
LONGITUDINAL ELEVATION
===
DETAIL OF PILE
FOOTINGS
=
12" LOG GIRDER
LONGITUDINAL ELEVATION
DISTANCE TO GZ = 9800"
TRANSVERSE SECTION “A"- "A"
|
TYPICAL EXISTING TIMBER BRIDGE.
(BRIDGE 1)
TRANSVERSE SECTION
SKETCH OF FUTURE STANDARD WOOD
BRIDGE CONSTRUCTION.
ELEVATION
DISTANCE TO GZ =5180'
GIRDER TRUSS
ame
4 /2"x 41/2" POSTS
111/2"x 91/2" FLOOR BEAM
pavelxexeee 3-3" BOLSTER 9 a 7 1/2" DECKING
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Taan SVERSE SECTION
YVIZIXIXINNISs
TRANSVERSE SECTION
—-
TYPICAL TIMBER BRIDGE ERECTED FOR
URGENT USE. (BRIDGE 43)
"1 172"x6"
9 exe ye° cROSS
DISTANCE TO GZ =4430'
toyz’ x0 V2"x50'-6"
FUTURE TYPICAL TIMBER
BRIDGE CONSTRUCTION FOR
E HIGHWAY & TROLLEY TRAFFIC
12"0X 39'-0" PILES (BRIDGE 28)
SECRET
TYPICAL TIMBER BRIDGES
HIROSHIMA, JAPAN
FIGURE 19 —XIT
7°X 7" BRAGING
~ 731568 O - 47 (Face p. 118) No, 13
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BRIDGE 6
SIMILAR TO BRIDGE |. WIDTH=17'-9". LENGTH= 266".
SKETCH OF BRIDGE
BRIDGE II
SUSPENSION SPAN=220'. WIDTH=9' CABLES = 31/2".
FOR DETAILS, PHOTOS I9 TO 23.
ELEVATION SKETCH
BRIDGE I3A
9 SPANS AT 33'.LENGTH=307' SECTION AS SHOWN BELOW.
6"x8" TIES
12"X24" GIRDERS
12"x12" CAP
SKETOH OF TRANSVERSE SECTION
BRIDGE 14
SIMILAR TO BRIDGES 186.
10 SPANS AT 30’. LENGTH #300’ .
WIDTH= 19"9"
BRIDGE I5
SIMILAR TO BRIDGES | 86.
14 4-PILE BENTS. LENGTH= 309".
WIDTH=19' 7 12"X 22" GIRDERS.
BRIDGE |8
SIMILAR TO BRIDGES 1&6.
15 4-PILE BENTS. LENGTH: 448°,
WIDTH=19' 7 12"X22" GIRDERS.
BRIDGE 21
SIMILAR TO BRIDGE 43.
9 7-PILE BENTS. LENGTH= 295:
WIDTH= 32-10" 12 10"LOG GIRDERS.
BENTS SKEWED APPROX. 15° TO LONGITUDINAL ¢ OF
BRIDGE.
BRIDGE 32
SIMILAR TO BRIDGE 43.
29 5-PILE BENTS. LENGTH=660'
WIDTH=18! 7 12"LOG GIRDERS.
6" EARTH ROADWAY ON 4"LOG DECK.
ADDITIONAL BRACING TO PILES IN BENTS.
SKETCH BELOW.
SKETCH OF PILE BENTS
BRIDGE
SIMILAR TO BRIDGES 1&6.
dl 4-PILE BENTS. LENGTH-312'
WIDTH =17'-10"
BRIDGE 36
SIMILAR TO “FUTURE STANDARD" BRIDGE.
6 3-PILE BENTS. LENGTH = I78!
WIDTH=10!
BRIDGE 38
SIMILAR TO BRIDGES 186.
10 4-PILE BENTS. LENGTH=330'
WIDTH= 12'-I"
BRIDGE 39
SIMILAR TO BRIDGES 1 8 6.
15 4-PILE BENTS. LENGTH= 415’
WIDTH = I6'-9"
BRIDGE 40
SIMILAR TO “FUTURE STANDARD" BRIDGE.
18 4-PILE BENTS. LENGTH= 42!'
WIDTH #17"-11"
BRIDGE 42 E :
SIMILAR TO “FUTURE STANDARD” BRIDGE.
13 4-PILE BENTS. LENGTH= 421’
WIDTH =17'-11"
BRIDGE 46
SIMILAR TO BRIDGES | & 6.
9 4-PILE BENTS. LENGTH= 220:
WIDTH = 13'-1"
BRIDGE 49
SIMILAR TO“FUTURE STANDARD" BRIDGE.
(0 2-PILE BENTS. LENGTH= 163!
WIDTH = 3\
NOTES FOR TIMBER BRIDGES
LFOR BRIDGES |,43@"FUTURE STANDARD", FIGURE 9.
2. IN MANY CASES, THE ACCURATE NUMBER OF SPANS COULD NOT
BE DETERMINED AND THE APPROXIMATE LENGTH OF BRIDGE
GOULD NOT BE MEASURED BECAUSE OF MISSING SPANS DUE
TO DAMAGE.
SECRET
TIMBER BRIDGES
HIROSHIMA, JAPAN
FIGURE 20 —XIL
731568 O - 47 (Face p. 118) No. 14
“ry . - i
teary
™ tes OR Ace.)
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Five reinforced-con-
crete beams 13 by 27 inches per span.
Decking: Seven-inch reinforced concrete with
14-inch asphalt wearing surface.
Abutments: Concrete.
Piers: Concrete.
SPECIAL FEATURES:
supports.
NOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards, Quality of materials good.
DAMAGE—EXTENT: Severe. Spans and
piers adjacent to south abutment severely dam-
aged.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Five.
Piers: Five.
Abutments: One.
REPAIRS NECESSARY
SERVICE:
Temporary: Four spans required with three
piers and one abutment.
Permanent: Five spans required with four
piers and one abutment.
REMARKS: Carrying a 16-inch
along the east side by bents.
PHOTOGRAPHS:
Beams haunched at
TO PLACE IN
water main
No. Direction and title
4 Looking west at flood damage of highway
bridge over the Enko-Gawa.
» Deck girder reinforcing steel.
6 Damaged concrete girders.
Steel reinforcement in concrete deck.
BRIDGE 4
Coordinates: 5J
Over River: Enko-Gawa.
Distance from “Zero Point”: Plan, 6450; slant,
6.750,
USE: Highway, pedestrian and trolley.
DESIGN TYPE: Reinforced concrete.
119
MATERIALS USED:
Longitudinal member: Fourteen reinforced-
concrete beams, 12 by 30 inches per span.
Decking: Seven-inch reinforced concrete with
asphalt wearing surface.
Abutments: Concrete.
Piers: Concrete with stone masonry at
corners.
SPECIAL FEATURES: Piers arched. Longi-
tudinal beams adjacent to abutments are
straight. All others are haunched except at
piers nearest to abutments which are hinged.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge were below United States
standards. Quality of materials good. Rail-
ings not doweled.
DAMAGE—EXTENT: None, except partly dam-
aged concrete railings along the north and south
elevation.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: Replace damage railings and
patch asphalt wearing surface.
REMARKS: Carrying a double-track trolley.
Blast strong enough to blow pedestrians to deck
and into river, and force autos tocurbs. Trolley
cars on bridge remained on tracks.
PHOTOGRAPHS:
No.
8 Looking south at north elevation of rein-
forced-concrete bridge over the Enko-
Gawa. Superficial blast damage at
northeast corner concrete railing.
Southeast corner of east abutment.
TO PLACE IN
Direction and title
9
BRIDGE 5
Coordinates: 5J
Over River: Enko-Gawa.
Distance from “Zero Point”
6.510,
: Plan, 6,210; slant,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Seven reinforced-con-
crete beams 15 by 27 inches per span.
Decking: Reinforced concrete with asphalt-
wearing surface,
Abutments: Concrete.
Piers: Concrete with stone masonry at cor-
ners,
SPECIAL FEATURES: Longitudinal beams
haunched at supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards. Quality of materials good.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Structure well protected from the
blast.
PHOTOGRAPHS:
No.
10
TO PLACE IN
Direction and title
Looking north at south elevation of rein-
forced-concrete bridge over the Enko-
Gawa. No damage.
Nore —Bridge 5A (steel-truss)
north of Bridge 5
0.
BRIDGE 5A
Coordinates: 5J
Over River: Enko-Gawa.
Distance from “Zero Point”: Plan, 6,160; slant,
6470.
USE: Water crossing.
DESIGN TYPE: Steel-truss.
MATERIALS USED:
Longitudinal member: 3- by 3- by 14-inch
angles,
120
MATERIALS USED—Continued
Decking: 3- by 3- by 14-inch angles and
2 by 14-inch bars comprising the steel
bracing.
Abutments: Concrete with masonry.
Piers: Concrete.
SPECIAL FEATURES: Top and bottom chords
parallel.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridges would
carry normal aqueduct loadings. Comparable
with similar structures in the United States.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar struc-
tures in United States. Materials good for con-
crete and masonry.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Aqueduct carrying 16-inch water
main,
PHOTOGRAPHS:
No, Direction and title
10 Steel-truss aqueduct south of Bridge 5.
No damage.
BRIDGE 6
TO PLACE IN
Coordinates: 41
Over River: Enko-Gawa.
Distance from “Zero Point”: Plan
5,730.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents,
MATERIALS USED:
Longitudinal member: Seven timber beams
per span. :
Decking: Timber.
Abutments: Concrete.
Piers: Four piles bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable,
5.870; slant
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Initially damaged by blast at approxi-
mate bridge center, later totally destroyed by
fire.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary :
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods,
PHOTOGRAPHS:
No.
11
TO PLACE IN
Direction and title
Looking south at remains of bridge over
the Enko-Gawa destroyed by blast and
flood,
BRIDGE 7
Coordinates: 41
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan 5200; slant
5,570,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Six reinforced-con-
crete beams, 16 by 20 inches per span.
Decking: Reinforced donerete with asphalt
wearing surface.
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Slight intrado effect.
Longitudinal beams were haunched at supports.
NOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards
* design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
principally because of lower
121
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Structure well protected from blast.
PHOTOGRAPHS:
TO PLACE
No, Direction and title
12 Looking west between reinforced-con-
crete, undamaged bridge and steel-truss
aqueduct over the Kyobashi-Gawa.
BRIDGE 7A
Coordinates: 41
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 5240; slant,
5,600.
USE: Water crossing.
DESIGN TYPE: Steel truss.
MATERIALS USED:
Longitudinal member: 4- by 6- by %g-inch
angles.
Decking: 3 by 3 feet by 3¢-inch angles by 2-
by 2- by %¢-inch angles, also 3- by 6- by
14-inch angles with piers, comprising
bracing.
Abutments: Concrete faced with stone and
brick masonry.
Piers: Concrete.
SPECIAL FEATURES: Top and bottom chords
parallel,
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridges would
carry normal aqueduct loadings. Comparable
with similar structures in United States.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar strue-
tures in United States. Materials good for
concrete and masonry.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
TO PLACE IN
REMARKS: Aqueduct carrying 22-inch water
main. Sheet-metal covering blown from pipe.
PHOTOGRAPHS:
No. Direction and title
12 - Looking west between reinforced-con-
crete Bridge 7 and steel aqueduct
Bridge 7A over the Kyobashi-Gawa.
No damage.
BRIDGE 8
Coordinates: 41
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 5.390; slant,
5,700.
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Five reinforced-con-
crete beams, 12- by 20-inch, per span.
Decking: Reinforced concrete with asphalt
wearing surface,
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES.
were haunched at supports.
pier caps.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—ENTENT: None, except railings to-
tally destroyed along both elevations. Asphalt
surface very badly pocketed.
CAUSE: Blast.
REPAIR AND SALVACE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: Replace destroyed concrete rail-
ings and patch asphalt wearing surface.
REMARKS: Pedestrians blown into river by
blast. Automobiles traveling along the bridge
not disturbed by blast.
Longitudinal beams
Piers haunched at
TO PLACE IN
122
PHOTOGRAPHS:
No,
13
Direction and title
Looking north at south elevation of
bridge over Kyobashi-Gawa. Supertfi-
cial blast damage to concrete railings.
BRIDGE 8A
Coordinates: 41
Over River: None.
Distance from “Zero Point”: Plan,
5900,
USE: Railroad.
DESIGN TYPE: I-beam girder.
MATERIALS USED:
Longitudinal member: 24-inch I-beam with
angle stiffeners.
Decking: Ties and rails.
Abutments: Concrete.
Piers: None.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridge would
carry normal railroad loadings. Comparable
with similar structures in United States,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar strue-
tures in United States. Materials good for con-
crete and masonry. :
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Entire single span.
Piers: None used.
Abutments : Botp.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a double-track railroad
line, and forms an underpass for highway and
pedestrian traffic.
PHOTOGRAPHS:
No.
14 Looking north at undamaged, steel-
girder, I-beam railroad bridge,
BRIDGE 9
5,580; slant,
TO PLACE IN
Direction and title
31
Coordinates :
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 5,730; slant,
6,050,
|
|
USE: Railroad.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: 69 and 75 inches in
depth.
Decking: Ties and rails.
Abutments: Concrete.
Piers: Concrete. Faced with stone and brick
masonry at corners.
SPECIAL FEATURES: Skewed at approxi-
mately 45°.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridges would
carry normal railroad loadings. Comparable
With similar structures in United States.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar strue-
tures in United States. Materials good for con-
crete and masonry.
DAMAGE—EXTENT: No structural damage to
girders, Only discolored paint due to bomb
effects along the south side. North face not
affected.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: None.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a double-track railroad
line,
PHOTOGRAPHS:
No, Direction and title
15 South elevation of undamaged double-
track railroad bridge over the Kyo-
bashi-Gawa.
16 Paint on south elevation of steel girder
discolored by exposure to bomb effects.
17 Paint on north elevation of steel girder
unaffected by bomb effects.
BRIDGE 10
TO PLACE IN
Coordinates: 31
Over River: Kyobashi-Gawa.
Stance from “Zero Point”: Plan, 6,950; slant,
7,250,
Pee Highway and pedestrian.
ESIGN TYPE: Reinforced concrete.
731568 —47—___.9
MATERIALS USED:
Longitudinal member: Five reinforced-con-
crete beams, 13 by 30 inches per span.
Decking: Reinforced concrete with asphalt
wearing surface,
Abutments: Concrete,
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal
haunched at supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: Moderate. The pier and
spans adjacent to the south abutment were
caused to settle.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: One pier and two spans.
REMARKS: Carrying a 20-inch water main along
the west side. Bridge opened to light traffic.
PHOTOGRAPHS:
No, Direction and title
18 Looking west at east elevation of bridge
over the Kyobashi-Gawa showing mod-
erate flood damage.
BRIDGE 11
beams
TO PLACE IN
Coordinates: 2T
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 7,960; slant,
8,200,
USE: Pedestrian.
DESIGN TYPE: Cable suspension.
MATERIALS USED:
Longitudinal member: Steel cable.
Decking: Timber, 114 by 6 inches.
Abutments: Concrete.
Piers: None.
SPECIAL FEATURES: Unusual
and vertical members. Eyes and hooks form
connection of crude type at ends of suspension
cables.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials fair.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
~XTENT USABLE:
Spans: The single suspension.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Constructed by the Japanese Army.
PHOTOGRAPHS:
suspension
TO PLACE IN
Direction and title
Looking southwest at corner of north
abutment.
Cable-tied vertical member, west suspen-
sion cable,
21 Looking west at east suspension cable,
undamaged.
22 Underside of deck structure.
23 Cable-tied vertical member of west sus-
pension cable,
BRIDGE 12
Coordinates: 5I
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 4,700; slant,
5,100.
USE: Highway and pedestrian.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Thirty-six inches in
depth.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete.
Piers: Concrete with stone facing at corners.
SPECIAL FEATURES: Longitudinal girders
haunched at supports. Ornamental stone fac-
ing on external girders,
124
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards. Quality of material good for con-
crete.
DAMAGE—EXTENT: No structural damage to
girders. Ornamental stone posts at the south-
east and southwest, corners slightly dislodged.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All."
Abutments: Both.
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary: None.
Permanent: Repair dislodged ornamental
stone posts. Patch asphalt wearing sur-
face.
REMARKS: Carrying a 16-inch water main.
PHOTOGRAPHS:
No. Direction and title
24 South elevation of bridge over the Kyo-
bashi-Gawa.
25 Ornamental stone post at southwest cor-
ner dislodged by blast.
26 Ornamental stone post at southeast cor-
ner dislodged by blast.
BRIDGE 13
Coordinates: 51
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 4,670; slant,
5,080,
USE: Trolley.
DESIGN TYPE: Plate girder (I-beam).
MATERIALS USED:
Longitudinal member: 24-inch I-beam with
angle stiffeners.
Decking: Ties and rails.
Abutments: Stone.
Piers: Four H-columns bent with angle brac-
ing.
SPECIAL FEATURES: Additional — timber
column bents with timber bracing added to each
bent. H-columns with angle extension fastened
to steel bents to carry electrical overhead service.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards, Quality of material fair for
timber.
DAMAGE—EXTENT: Slight deflection to sev-
eral main members. Slight damage to center
spans. Moderate damage to several of the spans
and bents along the bridge structure.
CAUSE: Blast and flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
* Temporary: Build up four center bents with
timber cribbing to normal elevation of trol-
ley tracks.
Permanent: Replace four center bents and
reset 24-inch I-section girder to normal
alignment and elevation.
REMARKS: Carrying a double-track trolley
line. Bridge was repaired and used during this
survey. An S-curve slope existed in trolley
rails across the bridge spans.
PHOTOGRAPHS:
No. Direction and title
TO PLACE IN
27 Timber cribbing under trolley tracks at
fourth span from east abutment of
blast- and flood-damaged bridge over
the Kyobashi-Gawa.
28 Looking west at cribbing under trolley
tracks at fifth span from east abutment.
29 South elevation of trolley bridge.
30 Flood and blast damage to bridge.
BRIDGE 13-A
Coordinates: 5I
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 4,670; slant,
5.080,
USE: Double-track trolley.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Four timber beams,
16 by 20 inches per span.
MATERIALS USED—Continued
Decking: Timber ties and rails.
Abutments: Stone masonry.
Piers: Four piles bent.
SPECIAL FEATURES: Timber extended over
abutments and set on soil without sills.
HOW DOES STRENGTH COMPARE WITII
UNITED STATES BRIDGES: Not ascer-
tainable,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Span adjacent to east abutment ini-
tially damaged by blast, later bridge totally de-
stroyed by fire.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary:
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No, Direction and title
TO PLACE IN
31 Looking east at blast- and fire-destroyed
timber bridge over the Kyobashi-Gawa.
32 Looking north. Destroyed by blast and
fire.
BRIDGE 14
Coordinates: 51
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 4,760; slant,
5,170.
USE: Pedestrian.
DESIGN ‘TYPE: Timber superstructure on pile
bents. |
MATERIALS USED:
Longitudinal member: Timber girders.
Decking: Timber.
Abutments: Stone masonry,
Piers: Four piles bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction,
CAUSE: By spreading of fires from adjacent
buildings.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None,
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary :
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No, Direction and title
33 Looking north at west abutment of fire
destroyed bridge over the Kyobashi-
Gawa.
BRIDGE 15
TO PLACE IN
Coordinates: 61
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 5,580; slant,
5,900.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Seven timber beams,
12 by 22 inch per span.
Decking: 4 by 10 inches.
Abutments: Concrete.
Piers: Four piles (12-inch diameter) per bent.
SPECIAL FEATURES: Used stapled connee-
tions rather than steel bolt.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All,
Piers: All,
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
TO PLACE IN
126
REMARKS: Bridge being used but timber deck-
ing decaying.
PHOTOGRAPHS:
No.
34 Looking south at undamaged bridge over
the Kyobashi-Gawa.
BRIDGE 16
Direction and title
Coordinates: 61
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 5,750; slant,
6,100,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete,
MATERIALS USED:
Longitudinal member: Fourteen reinforced-
concrete beams, 13 by 33 inch, per span.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete.
Piers: Concrete with
corners,
SPECIAL FEATURES: Some of the longitudi-
nal beams were haunched at supports,
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of material good.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
stone masonary at
TO PLACE IN
REMARKS: Structure fairly protected from
blast.
PHOTOGRAPHS:
No. Direction and title
85 Looking south showing the north eleva-
tion of undamaged reinforeed-concrete
highway bridge over the Kyobashi-
Gawa.
BRIDGE 17
Coordinates: TH
Over River: Kyobashi-Gawa.
Distance from “Zero Point”: Plan, 7,600; slant,
8,870.
USE: Highway, pedestrian and trolley.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: 54 inches in depth.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete with stone facing.
Piers: Concrete with stone facing.
SPECIAL FEATURES: Girders haunched and
anchored to pin-connected rockers at piers.
Stone masonry approach spans.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The railings not doweled. The
design, details and arrangements of the bridge
structure were below United States standards.
Quality of materials good for concrete and stone
masonry.
DAMAGE—EXTENT: No structural damage to
girders. Railings of main spans destroyed.
Approach spans railings not damaged.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: Replace damaged concrete rail-
ings.
REMARKS: Carrying double-track trolley line.
Carrying 12-inch water main.
pedestrians on structure during blast. -
PHOTOGRAPHS:
No. Direction and title
36 Looking south at trolley and highway,
plate-girder bridge over the Kyobashi-
Gawa. Superficial damage to concrete
railings by blast.
TO PLACE IN
No vehicles or
BRIDGE 18
Coordinates: 7G
Over River: Motoyasu-Gawa.
Distance from “Zero Point”: Plan, 6,000; slant,
6,300.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Seven timber beams,
12 by 22 inches per span.
Decking: Timber, 4 by 10 inches.
Abutments: Stone masonry.
Piers: Four piles (12-inch diameter) bent.
SPECIAL FEATURES: Used stapled connec-
tions rather than steel bolt.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards, lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Bridge being used but timber deck-
ing and railing in decayed condition.
PHOTOGRAPHS:
No. Direction and title
37 Looking north at undamaged highway
bridge over the Motoyasu-Gawa.
BRIDGE 19
TO PLACE IN
Coordinates: 6G
Over River: Motoyasu-Gawa.
Distance from “Zero Point”: Plan, 4,270; slant,
4,720,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced bents.
MATERIALS USED:
Longitudinal member: Seven reinforced-con-
crete beams, 13 by 20 inches per span.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal beams
were haunched at supports. Concrete cap
under beams only at every other pier.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards, principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: None. * ae.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments. Both.
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying an 18-inch water line
along the north side supported on steel brackets
and saddle along concrete bents.
PHOTOGRAPHS:
No.
38 Looking southeast at the north elevation
of highway bridge over the Motoyasu-
Gawa. Ornamental stone posts dis-
lodged by blast.
BRIDGE 20
Direction and title
Coordinates: 6G
Over River: Motoyasu-Gawa.
Distance from “Zero Point”: Plan, 2,900; slant,
3450.
USE: Highway and pedestrian.
DESIGN TYPE: I-beam girders.
MATERIALS USED:
Longitudinal member: six by 20-inch I-beam
with angle stiffeners.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Stone.
128
MATERIALS USED—Continued
Piers: Four- by 12-inch H-column_ bents
with 3- by 3- by 3¢-inch angles for diagonal
bracing.
SPECIAL FEATURES: H-column of bents set
in concrete footing.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards because of lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of material good for
concrete.
DAMAGE — EXTENT: Superficial: No strue-
tural damage to girders. Very slight damage to
railings. Very slight damage to steel bents.
CAUSE: Blast and flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: Replace broken concrete railings.
Minor repairs to steel bents.
REMARKS: Sixteen-inch water main carried by
brackets along steel bents.
PHOTOGRAPHS:
No, Direction and title
39 Looking south at slight blast damage to
northwest section of bridge over the
Motoyasu-Gawa.
40 South elevation showing debris against
bents deposited by flood.
BRIDGE 21
TO PLACE IN
Coordinates: 5H
Over River: Motoyasu-Gawa.
Distance from “Zero Point”: Plan, 1,450; slant,
2,460.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Twelve log girders,
10-inch per span,
Decking: Timber, 4 by 12 inches.
Abutments: Stone masonry.
Piers: Seven piles per bent (10-inch diame-
ter).
SPECIAL FEATURES: Bridge skewed approx-
imately 15°.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Spans at approximate bridge center ini-
tially damaged by blast, later totally destroyed
by flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary :
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No.
42
TO PLACE IN
Direction and title
Looking north at the southwest part of
bridge over the Motoyasu-Gawa de-
stroyed by blast and flood.
BRIDGE 22
Coordinates: 5H
Over River: Motoyasu-Gawa.
Distance from “Zero Point”: Plan, 260; slant,
2,020,
USE: Highway and pedestrian.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Thirty
depth.
Decking: Reinforced concrete with asphalt
wearing surface,
Abutments: Concrete faced with masonry.
Piers: Concrete faced with masonry.
SPECIAL FEATURES: Girders haunched at
supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards. Quality of materials good for con-
crete and masonry.
inches in
. REPAIRS NECESSARY
129
DAMAGE—EXTENT: No structural damage to
girders. Concrete railings completely de-
stroyed. Ornamental posts dislodged.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
TO PLACE IN
SERVICE:
Temporary: None.
Permanent: Replace railings. Replace and
reset ornamental posts. Resurface part of
deck near abutments.
REMARKS: Nearest bridge to the zero point
covered in the survey carrying a 16-inch water
line,
PHOTOGRAPHS:
No.
43
Direction and title
Superficial blast damage to bridge over
the Motoyasu-Gawa.
44 North elevation. No structural damage.
45 Stone posts and railings damaged by
blast.
46
BRIDGE 23
Blast effect on ornamental stone posts.
Coordinates: 4H
Over River: Ota-Gawa.
Distance from “Zero Point”: Plan, 860; slant,
2,170.
USE: Highway and pedestrian.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Thirty-nine inches in
depth.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete faced with stone ma-
sonry.
Piers: Concrete.
SPECIAL FEATURES: Girders haunched at
supports. Girders abutting the south fact of
Bridge 24 are cantilevered.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards. Quality of materials good for con-
crete and masonry.
DAMAGE—EXTENT: Superficial. No strue-
tural damage to piers. Ornamental posts at
south end of bridge slightly dislodged. Con-
crete railings along both sides of bridge com-
pletely destroyed.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: One.
for this bridge.
REPAIRS NECESSARY
SERVICE:
Temporary: No repairs necessary for tem-
porary use.
Permanent: Replace concrete railings. Reset
posts,
REMARKS: None.
PHOTOGRAPHS:
No. Direction and title
Note: only one abutment
TO PLACE IN
47 Looking east at west elevation of Bridge
23. Note cantilever span to Bridge 24
over the Ota-Gawa.
48 Cast-iron post sections 5 feet on center for
concrete railing sheared off east curb by
blast.
49 Cast-iron post sections and concrete rail-
ing along west curb destroyed by blast.
BRIDGE 24
Coordinates: 4H
Over River: Ota-Gawa.
Distance from “Zero Point”: Plan, 1,000; slant,
2,230.
USE: Highway, pedestrian and trolley.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Forty-eight inches in
depth.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete faced with stone ma-
sonry.
Piers: Concrete with stone masonry at cor-
ners.
SPECIAL FEATURES: Girders haunched at
supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards. Quality of materials good for con-
crete and masonry.
DAMAGE—EXTENT: Several main members
slightly deflected. Concrete railings destroyed.
Granite curbs and concrete walks partly de-
stroyed. Concrete deck damaged. Trolley
rails displaced at bridge ends. Ornamental
stone posts of bridge damaged.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary: No repairs necessary for tempo-
rary service,
PLACE IN
Permanent: Replace railings. Reset all
power poles. Remove and replace all dam-
aged walks, curbs, and roadway deck. Re-
surface part of deck.
REMARKS: Carried a double-track trolley line.
The most used and outstanding bridge of the
city of Hiroshima. It was the aiming point of
the atomic bomb dropped at Hiroshima.
PHOTOGRAPHS:
No, Direction and title
50 North elevation of bridge over Ota-Gawa.
Conerete walk and railing damaged by
blast.
51 Southeast part of bridge over Ota-Gawa.
Railings damaged by blast.
52 Blast damage to southwest section, Con-
crete walk raised 20 inches above origi-
nal road grade. Granite curbs moved
914 inches south from original position.
53 North elevation adjacent to east abut-
ment. No structural damage to plate
girders.
PHOTOGRAPHS—Continued
No. Direction and title
54 Portion of north granite curb and walk.
Drain scupper west of bridge 23 ele-
vated 20 inches above road grade by
blast effects.
Portion of north granite curb and walk.
Drain seupper east of bridge 28 ele-
vated 24 inches above road grade,
North concrete walk raised 38 inches
above cross steel members, supporting
the north walk, by blast effects.
Blast effects moved roadway slab later-
ally 15 inches north and raised it 14
inches above original position. Note
pushed-up scupper.
Northwest corner of bridge showing blast
damage to concrete walk, granite curb,
and roadway concrete deck.
Northeast corner of bridge showing blast
damage to conerete walk and granite
curb.
Intersection of Bridge 28 and Bridge 24.
Rails of south trolley tracks pushed up
8 inches above original road grade by
blast.
Blast damage. Cast-iron post sections at
northwest corner of intersection of
Bridges 28 and 24. Post sections 5 feet
on center for concrete railings of
Bridge 23 and 6 feet on center for
Bridge 24.
Northeast. corner, steel-plate girder.
structural damage by blast.
Underside of steel plate girders and cross-
members at east abutment. Slight de-
fection.
Underside of steel-plate girders and cross-
members at west abutment. No struc-
tural damage.
Secondary framing of exterior girder
under north walk at approximate
bridge center. No structural damage.
Inside faces of plate girders fourth span
from east abutment under north walk.
Deflected slightly by blast.
Inside faces of plate girders. Fifth span
from east abutment under north walk,
Deflected slightly by blast.
East end of bridge. Slight deflection in
trolley rails due to shifting of bridge
deck by blast.
oH
-1
55
59
60
61
No
63
64
65
66
68
131
PHOTOGRAPHS—Continued
No. Direction and title
69 West end of bridge. Trolley rails moved
laterally 15 inches to the north as blast
effect shifted bridge deck.
70 Intersection of Bridge 23 (left) and
Bridge 24 (right). All damage from
blast effects. Bridge 23 (860 feet to
GZ, 2170 feet to AZ). Bridge 24
(1,000 feet to GZ, 2,230 feet to AZ).
BRIDGE 25
Coordinates: 3H
Over River: Ota-Gawa.
Distance from “Zero Point”: Plan, 5,200; slant,
5570.
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Seven reinforced-con-
crete beams, 13 by 24 inch per span.
Decking: Reinforced concrete (8
asphaltic wearing surface.
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Some of the longitudi-
nal beams were haunched at supports. Bridge
is skewed.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, bridges were designed to carry lower
loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: Moderate to piers. Su-
perficial to coping. One pier entirely destroyed
inches)
and one pier partly damaged by flood. Deck
over damaged piers also partly broken. Coping
blown off by blast along both railings. Railing
very slightly damaged by blast.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: For heavy traffic loads, bents to
be rebuilt and spans restored.
TO PLACE IN
REPAIRS NECESSARY TO PLACE IN
SERVICE—Continued
Permanent: Restore two spans and two bents.
Also restore coping for railings and repair
part of the railings.
REMARKS: Portion of two spans, continuous
section unsupported for complete length.
Bridge opened to light traffic.
PHOTOGRAPHS:
No,
71
Direction and title
Looking north at west elevation of bridge
over Ota-Gawa. Flood damage. Su-
perficial damage to concrete coping by
blast. 4
BRIDGE 26
Coordinates: 3H
Over River: Ota-Gawa.
Distance from “Zero Point”®: Plan, 5,750; slant,
6,100.
USE: Railroad.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Seventy-
in depth.
Decking: Ties and rails.
Abutments: Concrete.
Piers: Concrete faced with brick.
SPECIAL FEATURES: Bridge skewed slightly.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridge would
carry normal railroad loadings. Comparable
with similar structures in United States.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar strue-
tures in United States. Materials good for con-
crete and masonry.
DAMAGE—EXTENT: No structural damage to
girders. Discoloring of old paint due to bomb
effects along the south side of bridge. North
face unaffected.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
eight inches
TO PLACE IN
132
REMARKS: Carries a double-track railroad.
PHOTOGRAPHS:
No, Direction and title
72 South elevation of undamaged, double-
track railroad bridge over Ota-Gawa.
73 Paint on the south elevation of girders
discolored by exposure to bomb effects.
74 Paint on the north elevation of girders
unaffected by bomb effects.
BRIDGE 27
Coordinates: 3G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 4,360; slant,
4,790.
USE: Highway and pedestrian.
DESIGN TYPE: Steel arch.
MATERIALS USED:
Longitudinal member : Box chord. Top mem-
bers of truss.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete.
Piers: None.
SPECIAL FEATURES: Tied arch at anchorage
with 5- by 8-inch I-section vertical members. No
diagonal bracing.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good for
masonry.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Entire single span.
Piers: None used,
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a 10-inch water main.
TO PLACE IN
PHOTOGRAPHS:
No. Direction and title
75 West eleVation of bridge over the Temma-
Gawa undamaged. Paint on the mem-
bers of the east elevation were dis-
colored by exposure to bomb effects.
Steel members of the west elevation
were slightly discolored.
BRIDGE 28
Coordinates: 3G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 4430; slant,
4,840,
USE: Highway, pedestrian and trolley.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Timber beams.
Decking: Timber.
Abutments: Concrete.
Piers: Timber pile bents.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary :
Permanent; New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No. Direction and title
PLACE IN
76 Looking north at remains of bridge at
north abutment over tne Temma-Gawa
destroyed by flood.
BRIDGE 29
Coordinates: 5G
Over River: Ota-Gawa.
Distance from “Zero Point”: Plan, 1,190; slant,
2,310.
USE: Highway and pedestrian.
DESIGN TYPE: Steel truss.
MATERIALS USED:
Longitudinal member: Box chord for top
members of truss. Eye-bars for tension
members.
Decking: Timber.
Abutments: Concrete faced with masonry.
Piers: Concrete faced with masonry.
SPECIAL FEATURES: Pin-connected
truss of unusual design.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standard. Quality of materials fair for
timber and good for masonry and concrete,
DAMAGE—EXTENT: Complete destruction.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: Three new spans.
Permanent: New bridge required with the ex-
ception of piers and abutment,
REMARKS: Carries 16-inch water main.
PHOTOGRAPHS:
No. Direction and title
steel
TO PLACE IN
77 Looking north at remains of bridge over
the Ota-Gawa. Destroyed by blast.
78 Looking northeast at southwest corner,
destroyed by blast.
79 Looking south at east abutment.
destroyed by blast.
80 Looking east at debris of bridge structure
at west abutment. Bridge destroyed
by blast.
BRIDGE 30
Bridge
Coordinates: 5G
Over River: Ota-Gawa.
Distance from “Zero Point”: Plan, 1,930; slant,
2.800.
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Seven reinforced-con-
crete beams, 12 by 36 inch per span.
Decking: Reinforced concrete (6-inch) with
asphalt wearing surface.
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal
were haunched at supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of material good.
DAMAGE — EXTENT: Severe. Four center
spans destroyed and second span from west end
being held by reinforcing steel, at pier adjacent
to west abutment. Major portion of railing
destroyed.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Two spans near east end and one span
near west end.
Piers: Two bents near east end and one pier
near west end.
Abutments: Both.
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary: Rebuild four spans and three
bents between existing structures.
Permanent: Restore four spans and three
concrete bents, also replace railings.
REMARKS: Nearest reinforced-concrete bridge
to the zero point.
beams
PHOTOGRAPHS:
No. Direction and title
81 Looking north at flood-damaged highway
bridge over the Ota-Gawa.
82 Roadway deck and girder reinforcing
steel,
83 Steel reinforcement in concrete girder.
84 Roadway deck and girder, reinforcing
steel.
BRIDGE 30A
Coordinates: 5G
Over River: Ota-Gawa.
134
Distance from “Zero Point”: Plan, 1,880; slant,
2,750.
USE: Water crossing.
DESIGN TYPE: Steel truss.
MATERIALS USED:
Longitudinal member: 3- by
angles.
Decking: 2- by 2- by 44-inch angles, 14- by
2-inch bars comprising the steel bracing.
Abutments: Stone masonry.
Piers: Concrete.
SPECIAL FEATURES: Bow truss.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridge would
carry normal aqueduct loadings. Comparable
with similar structures in United States.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar strue-
tures in United States. Materials good for con-
crete and masonry.
DAMAGE—EXTENT: Slight.
of truss slightly deformed.
CAUSE: Blast.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All,
Abutments: Both.
»
3- by %¢-inch
Steel members
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary: None.
Permanent: None.
REMARKS:
Aqueduct, carrying a 16-inch water line.
PHOTOGRAPHS:
No. Direction and title
85 North elevation of bridge over the Ota-
Gawa slightly damaged by blast.
Aqueduct carrying a 16-inch water
main.
86 Looking northeast at corner of west
abutment. Steel truss members slightly
damaged by blast. Note damaged cov-
ering of 16-inch water main.
BRIDGE 31
Coordinates: 6G
Over River: Ota-Gawa.
Distance from “Zero Point”: Plan, 4,570; slant,
5,000,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Seven reinforced-con-
crete beams, 16 by 20 inch per span.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal beams
were haunched at support.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: Severe. All spans de-
stroyed except one on east end and four spans
on the west end of bridge. Railing, also, partly
destroyed.
CAUSE: Flood.
REPATR AND SALVAGE:
EXTENT USABLE:
Spans: Four near west end and one span near
east end.
Piers: Five concrete bents.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: Rebuild seven spans and six
bents.
Permanent: Restore seven concrete spans and
six concrete bents; also, replace railings.
REMARKS: Carrying 16-inch water main along
the north side by bents.
PHOTOGRAPHS:
No, Direction and title
87 Looking south at flood-damaged highway
bridge over the Ota-Gawa.
Top portion of the northwest corner post
dislodged by blast.
BRIDGE 32
Coordinates: TE, F
TO PLACE IN
Over River: Temma-Gawa,
Distance from “Zero Point”: Plan, 9,400; slant,
9,600,
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents,
MATERIALS USED:
Longitudinal member: Seven log beams (12-
inch diameter) per span.
Decking: Four-inch logs.
Abutments: Stone masonry.
Piers: Five piles, 12-inch diameter per bent.
SPECIAL FEATURES: Unusual deck construe-
tion. More diagonal bracing than ordinary.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards, lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair.
DAMAGE—EXTENT: Severe.
CAUSE: The center portion of bridge severely
damaged by flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Approximately 16.
Piers: Approximately 16.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary: Replace 15 bents and 16 spans.
Permanent: Replace 15 bents and 16 spans.
REMARKS: Constant replacement of piling re-
quired after floods,
PHOTOGRAPHS:
No. Direction and title
88 Looking north at flood damaged highway
bridge over the Temma-Gawa.
BRIDGE 33
PLACE IN
Coordinates: 6F
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 5,300; slant,
5,650.
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member; Five reinforced-con-
crete beams, 13 by 18 inch per span.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete,
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal beams
were haunched at supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards, principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: Severe. Eight spans
and seven concrete bents completely destroyed.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Four adjacent to west abutment.
Piers: Three concrete bents.
Abutments: Both.
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary: Rebuild eight spans and seven
bents.
Permanent: Restore eight concrete spans and
seven concrete bents; also, replace railings.
REMARKS: Carrying 16-inch water main by
bents.
PHOTOGRAPHS:
No.
Ss)
Direction and title
Looking west at flood damaged bridge
over the Temma-Gawa.
BRIDGE 34
Coordinates: 5G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 3,700; slant,
4,200.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Timber beam.
Decking: Timber.
Abutments: Stone masonry.
Piers: Four piles per bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Spreading of fires from adjacent build-
ings.
REPAIR AND SALVAGE:
136
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary:
Permanent: New bridge required.
REMARKS: Constant replacement of piling
after floods.
PHOTOGRAPHS:
NO:i8 3 Direction and title
90 Looking west at timber bridge over the
‘Temma-Gawa, completely destroyed by
fire.
BRIDGE 35
Coordinates: 5G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 3,190; slant,
3,750,
USE: Trolley (double track).
DESIGN TYPE: I-beam girder.
MATERIALS USED:
Longitudinal member : I-beam (24-inch) with
angle stiffeners.
Decking: Ties and rails.
Abutments: Stone,
Piers: H-column bents with diagonal bracing.
SPECIAL FEATURES: Steel H-column poles
carrying trolley overhead electric system,
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair for
timber.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary:
Permanent: New bridge required.
REMARKS: Carried a double-track trolley line.
TO PLACE IN
PHOTOGRAPHS:
No. Direction and title
8 Looking north at remains of bridge (at
east abutment) over the Temma-Gawa,
completely destroyed by flood. °
Looking west at remains of trolley bridge
(at west abutment) destroyed by flood.
BRIDGE 36
92
Coordinates: 5G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 3,200; slant,
3,760.
USE: Pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Five log beams (12-
inch diameter) per span.
Decking: Timber, 2 by 6 inches.
Abutments: Stone masonry.
Piers: Three pile (12-inch diameter) bents.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary :
Permanent: New bridge required,
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No.
3
TO PLACE IN
Direction and title
Looking west at remains of bridge (east
and west abutments) over the Temma-
Gawa, completely destroyed by flood.
BRIDGE 37
is
Coordinates: 5G
Over River: Temma-Gawa.
Distance from “Zero Point”
3,770,
: Plan, 3,220; slant,
137
USE: Highway and pedestrian.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Fifty inches in depth.
Decking: Timber, 4 by 12 inches.
Abutments: Concrete.
Piers: Concrete.
SPECIAL FEATURES: Fourteen-inch water
main carried by brackets along the south side.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair for
wood,
DAMAGE—EXTENT: Severe. Two spans and
one pier completely destroyed, adjacent to west
abutment.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Two.
Piers: Two.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: One pier and two spans.
Permanent: One pier and two spans.
REMARKS; Destroyed spans being replaced by
timber construction to permit immediate use of
the bridge.
PHOTOGRAPHS:
No.
94 Looking north at plate girder, timber-
decked highway bridge over the ‘Tem-
ma-Gawa. Westerly portion severely
damaged by flood.
Fourteen-inch water main carried by
brackets along the south side.
BRIDGE 38
TO PLACE IN
Direction and title
Coordinates: 4G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 3,750; slant,
4,250.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Timber beams.
Decking: Timber.
Abutments: Stone masonry.
Piers: Four piles (10-inch diameter)
bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Westerly half severely damaged by fire,
later completely destroyed by flood.
REPAIR AND SALVAGE:
SXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary:
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
per
TO PLACE IN
No. Direction and title
95 Looking west at remains of timber bridge
over the Temma-Gawa severely dam-
aged by fire (west half) and completely
destroyed by flood.
BRIDGE 39
Coordinates: 4G
Over River: Temma-Gawa.
Distance from “Zero Point”: Plan, 3,880; slant,
4,390.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Seven timber beams,
6- by 14-inch, per span.
Decking: Timber, 2 by 10 inches.
Abutments: Stone masonry.
Piers: Four piles per bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascertain-
able.
138
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Easterly third severely damaged by fire,
later completely destroyed by flood.
REPATR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary :
Permanent: New bridge required.
REMARKS: Constant replacement of piling,
required after floods.
PHOTOGRAPHS:
No.
6
TO PLACE IN
Direction and title
Looking northwest at remains of timber
bridge over the Temma-Gawa severely
damaged by fire, easterly one-third and
completely destroyed by flood.
BRIDGE 40
3G
Coordinates:
Over River: Fukushima-Gawa.
Distance from “Zero Point”: Plan, 5,360; slant,
5,700.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Seven timber beams,
6 by 14 inch per span.
Decking: Timber, 2 by 10 inches,
Abutments: Concrete.
Piers: Four piles, 10-inch diameter per bent.
SPECIAL FEATURES: Used stapled connec-
tions rather than steel bolt.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair.
DAMAGE—EXTENT: Severe.
CAUSE: The northerly portion of bridge severely
damaged by fire.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: Eight (southerly portion of bridge).
Piers: Eight (southerly portion of bridge).
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: Replace 10 spans and 9 bents.
Permanent: Replace 11 spans 10 bents.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No. Direction and title
97 Looking at bridge over the Fukushima-
Gawa, northerly portion severely dam-
aged by fire.
BRIDGE 41
TO PLACE IN
Coordinates: 5F
Over River: Between Yamate-Gawa and Fuku-
shima-Gawa.
Distance from “Zero Point”: Plan, 6,150; slant,
6460,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Four reinforced-con-
crete beams, 12 by 14 inch per span.
Decking: Reinforced concrete (8-inch).
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal beams
were haunched. Simply supported.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads,
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Structure well protected from blast.
PLACE IN
731568—47 —10
PHOTOGRAPHS:
No. Direction and title
98 Looking west at undamaged concrete
bridge between the Yamate Gawa and
the Fukushima Gawa.
BRIDGE 42
Coordinates: 4F
Over River: Fukushima-Gawa.
Distance from “Zero Point”: Plan, 5,100; slant,
5A90.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Timber beams.
Decking: Timber, 2 by 6 inches.
Abutments: Stone masonry and timber.
Piers: Four piles (10-inch diameter) per
bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials fair.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Bridge completely destroyed by flood
with the exception of one span near the west
abutment and two bents.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: One.
Piers: Two.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary: Replace 13 spans and 13 bents.
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods,
PHOTOGRAPHS:
No. Direction and title
99 Looking west at remains of timber bridge
(east and west abutments) over the
Fukushima-Gawa destroyed by flood.
BRIDGE 43
PLACE IN
Coordinates: 4F
Over River: Fukushima-Gawa.,
Distance from “Zero Point”: Plant, 5,180; slant,
5,510.
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Timber logs 4 per
span.
Decking: Timber.
Abutments: Stone masonry.
Piers: Four piers per bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction,
CAUSE: The two mid-spans initially damaged
by blast, later completely destroyed by fire which
spread to adjacent buildings.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary:
Permanent: New bridge required.
REMARKS: A new timber bridge was erected
for urgent use immediately after blast and fire
TO PLACE IN
damage.
PHOTOGRAPHS:
No. Direction and title
100 Looking south at north elevation of
newly constructed timber bridge over
the Fukushima-Gawa. Old bridge
was destroyed by blast and fire.
BRIDGE 44
Coordinates:
4F and 5F
Over River: Fukushima-Gawa.
Distance from “Zero Point”: Plan, 5,300; slant,
5,650,
USE: Trolley.
DESIGN TYPE: L-beam girder.
MATERIALS USED:
Longitudinal member: I-beam 24-inch with
angle stiffeners,
Decking: Ties and trolley rails.
Abutments: Stone.
140
MATERIALS USED—Continued
Piers: Four H columns per bent with diagonal
bracing. H columns set in concrete.
SPECIAL FEATURES: Steel, H-column, elee-
tric poles carrying trolley overhead system.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair for
timber.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All,
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a double-track trolley
line,
PHOTOGRAPHS:
TO PLACE IN
No, Direction and title
101 Looking northwest at the southeast area
of undamaged trolley bridge over the
Fukushima-Gawa.
BRIDGE 45
Coordinates: 5E
Over River: Fukushima-Gawa.
Distance from “Zero Point”: Plan, 7,010; slant,
7,300,
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Five reinforced-con-
crete beams, 13 by 18 inch per span.
Decking: Reinforced concrete (8-inch) with
asphalt wearing surface.
Abutments: Concrete.
Piers: Concrete bents.
SPECIAL FEATURES: Longitudinal beams
were haunched at supports.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: Moderate. Two con-
crete spans and two concrete bents near east
abutment partly damaged due to settlement.
Railing also partly damaged at the southeast
and northeast corners.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary: None.
Permanent: Restore two concrete spans and
bents. Also replace damaged railings.
REMARKS: Bridge opened to light traffic.
PHOTOGRAPHS:
No. Direction and title
PLACE IN
102. Looking northwest at the southeast area
of concrete highway bridge over the
Fukushima-Gawa moderately dam-
aged by flood.
BRIDGE 46
Coordinates: 5E
Over River: Yamate-Gawa.
Distance from “Zero Point”: Plan, 8,090; slant,
5.350,
USE: Highway and pedestrian.
DESIGN TYPE: Timber superstructure on pile
bents.
MATERIALS USED:
Longitudinal member: Timber beams.
-Decking: Timber.
Abutments: Stone masonry.
Piers: Four piles per bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction,
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary :
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
No, Direction and title
PLACE IN
103 Looking west at remains of timber
bridge over the Yamate-Gawa com-
pletely destroyed by flood.
BRIDGE 47
Coordinates: 4E
Over River: Yamate-Gawa.
Distance from “Zero Point”: Plan, 7,450; slant,
7,700,
USE: Trolley.
DESIGN TYPE: I-beam girder.
MATERIALS USED:
Longitudinal member: I-beam 24 inch with
angle stiffeners.
Decking: Ties and trolley rails.
Abutments: Stone and concrete.
Piers: Four H-columns per bent with diago-
nal bracing. H-columns set in concrete.
SPECIAL FEATURES: Steel H-column, elec-
tric poles carrying trolley overhead system.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards; lower design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge structure were below United
States standards. Quality of material fair for
timber,
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY TO
SERVICE:
Temporary: None.
Permanent: None.
PLACE IN
REMARKS: Furthermost trolley bridge from the
zero point. Carrying double-track trolley line.
PHOTOGRAPHS:
No. Direction and title
104 Looking at undamaged trolley bridge
over the Yamate-Gawa.
BRIDGE 48
Coordinates: 4
Over River: Yamate-Gawa.
Distance from “Zero Point”: Plan, 7,130; slant,
TA00.
USE: Highway and pedestrian.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: 42 inches in depth.
Decking: Reinforced concrete with asphalt
wearing surface.
Abutments: Concrete.
Piers: Concrete with stone facing at croners.
SPECIAL FEATURES: Girders not haunched.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: More massive.
Generally, the bridges were designed to carry
lower loadings than is American practice.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details and arrange-
ments of the bridge were below United States
standards. Quality of materials good for con-
crete and masonry.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying 12-
mains.
PHOTOGRAPHS:
No,
105
TO PLACE IN
and 14-inch water
Direction and title
Looking north. Showing the south
elevation.
BRIDGE 49
Coordinates: 3F
Over River: Yamate-Gawa.
142
Distance from “Zero Point”: Plan, 6,380; slant,
6,650.
USE: Pedestrian.
DESIGN TYPE:
bents.
MATERIALS USED:
Longitudinal member :
Decking: Timber.
Abutments: Stone masonry.
Piers: Two piles per bent.
SPECIAL FEATURES: None.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Not ascer-
tainable.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Not ascertainable.
DAMAGE—EXTENT: Complete destruction.
CAUSE: Flood.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: None.
Piers: None.
Abutments: None,
REPAIRS NECESSARY
SERVICE:
Temporary :
Permanent: New bridge required.
REMARKS: Constant replacement of piling re-
quired after floods.
PHOTOGRAPHS:
Timber superstructure on
TO PLACE IN
No, Direction and title
106 Looking northwest at remains of timber
foot bridge over the Yamate-Gawa
destroyed by flood.
BRIDGE 50
Coordinates: 3G
Over River: Yamate-Gawa.
Distance from “Zero Point”: Plan, 6,580; slant,
6,900,
USE: Railroad.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Forty-nine inches in
depth.
Decking: Ties and rails.
Abutments: Concrete.
Piers: Concrete faced with brick masonry at
corners.
SPECIAL FEATURES: Skewed approximately
45°.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridge would
carry normal railroad loadings. Comparable
With similar structures in United States.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar strue-
tures in United States. Materials good for con-
crete and masonry.
DAMAGE—EX'TEN T: Nostructural damage to
girders, only discoloring of old paint along the
south face of bridge. North face unaffected.
CAUSE: Bomb effects.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All. é
Abutments: Both.
REPAIRS NECESSARY TO PLACE IN
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a double-track railroad
line,
PHOTOGRAPHS:
No,
107
Direction and title
South elevation. Undamaged — plate-
girder, railroad bridge over the Ya-
mate-Gawa. Paint of girders on the
south elevation slightly discolored by
exposure to bomb effects. North ele-
vation unaffected by bomb effects.
BRIDGE 51
Coordinates: 3G
Over River: Underpass.
Distance from “Zero Point”: Plan, 6,450; slant,
6,780,
USE: Railroad.
DESIGN TYPE: Plate girder.
MATERIALS USED:
Longitudinal member: Forty-eight and 36
inches in depth.
Decking: Ties and rails.
Abutments: Concrete.
Piers: Concrete.
SPECIAL FEATURES: Skewed approximately
45°,
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Bridges would
carry normal railroad loads. Comparable with
similar structures in United States.
143
QUALITY OF CONSTRUCTION AND MA-
TERIALS: Comparable with similar structures
in United States. Materials good for concrete
and masonry.
DAMAGE—EXTENT: No structural damage to
girders. Only discoloring of old paint due to
bomb effects along the south face of bridge.
North face unaffected.
CAUSE: Bomb effects.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Carrying a double-track railroad
line,
PHOTOGRAPHS:
No.
108
TO PLACE IN
Direction and litle
South elevation. Undamaged, plate-
girder, railroad bridge and underpass.
Paint of girders on the south eleva-
vation slightly discolored by exposures
to bomb effects. North elevation un-
ulfected by bomb effects.
Showing printed information on the face
of the north plate girder at east abut-
ment, Cooper E—10 loading.
BRIDGE 52
109
Coordinates: SJ
Over River: Creek.
Distance from “Zero Point”: Plan, 12,200; slant,
12,450.
USE: Highway and pedestrian.
DESIGN TYPE: Reinforced concrete.
MATERIALS USED:
Longitudinal member: Three reinforced-con-
crete beams, 13 by 21 inch per span.
Decking: Seven-inch reinforced concrete.
Abutments: Concrete.
Piers: Concrete.
SPECIAL FEATURES: Longitudinal beams
were haunched at support with cantilever spans
at center of bridge.
HOW DOES STRENGTH COMPARE WITH
UNITED STATES BRIDGES: Below United
States standards principally because of lower
design loads.
QUALITY OF CONSTRUCTION AND MA-
TERIALS: The design, details, and arrange-
ments of the bridge structure were below United
States standards. Quality of materials good.
DAMAGE—EXTENT: None.
CAUSE: None.
REPAIR AND SALVAGE:
EXTENT USABLE:
Spans: All.
Piers: All.
Abutments: Both.
144
REPAIRS NECESSARY
SERVICE:
Temporary: None.
Permanent: None.
REMARKS: Furthermost bridge from the zero
point.
PHOTOGRAPHS:
No. Direction and title
TO PLACE IN
110 General oblique view showing most re-
mote bridge included in study, 12,200
feet to GZ, 12,450 feet to AZ.
Part A.
B.
Cc.
D.
E,
F.
Ga.
SECTION XIII
DAMAGE TO SERVICES AND UTILITIES
Page
Electric railway and bus system - __-_- t Ses ooo I Ee Eo 146
Government railroad system_——_______~ NAR. occ ew ese be Mee es ee ae nee ee eee eee 170
Blectric ‘generating‘and -distributioneysteme uses... .j sees eee oe ae bce SEE eee ecw adeeb gees 188
EBLEDNONG COMMUNICATIONS SU RUOINe se Oe soo epee ee ree een tee eee on ree Se 212
Water supply system_ 3 Fath Rey wate oe Coes oar eee ees ae BNE wigs cid als af oe 226
Sanitary and storm sewer system _ SS an Hie ee we a oe ee Re I Oe ae ee gate 268
Domestie gas system — Mo a OR 555 EA ese eee ae anaes ences 287
Photos 1-164, inclusive.
Figures 1-51, inelusive.
Tables 1-42, inclusive.
145
A. CITY ELECTRIC RAILWAY AND BUS
SYSTEM
1. Summary
a, Trafic. Wiroshima, a city of approximately
245,000 persons, depended almost entirely upon
the Hiroshima Electric Railway Co., Inc., for
transportation within the city itself and to the
outlying districts, including the resort town of
Miyajima, about 10 miles to the southwest. The
greatest recorded passenger traffic per month was
4,200,000 persons within the city and 800,000 per-
sons using the Miyajima line during July 1945.
b. Equipment. The Sendamachi station, with
the main offices, converter station, and warehouses
and repair units within the station area was the
base of operations. The Yagurashita converter
station was situated in another part of town and
divided the power output required to operate the
system. Figure 1 shows the location of the sta-
tions and the extent of the railway system. Both
stations, Sendamachi and Yagurashita, received
electrical power from the Chugoku Electric Co., of
Hiroshima, at 22 kilowatts AC, transforming and
converting the alternating current to 600 volts
DC. which was the operating voltage.
ec. Street Railway Cars. The railway company
operated 123 cars, the largest of which weighed 18
tons empty and 26 tons loaded, and was rated at
37.3 kilowatts. An overhead system provided elec-
tric power to the cars for operation.
d. Transmission System. The overhead system
was supported by wood, steel, and concrete poles,
and a single copper conductor per pair of rails
provided the elect ric power for the street railway
cars. The entire 15.5 miles of the system within
the city were double track, as were 6 of the 10 miles
of the Miyajima section. The rails were of United
States and Japanese manufacture, having a gauge
of 4 feet 8.5 inches, set on 8-inch ties 7 feet long.
e. Bridges. Tecause of the delta formation of
the city, 8 bridges constructed of timber and steel
were required to complete the track system,
f. Buses. The company employed 85 buses to
serve areas not reached by street cars. Since gaso-
line was so scarce, buses were driven on a gaseous
fuel which was produced by a unit carried on each
bus as a part of the equipment,
g. Damage to Buildings. ‘The atomic bomb ex-
ploded at 2.000 feet above ground zero (GZ) which
is indicated on Figure 1. Primary blast damage
put the whole transportation system out of service.
146
Buildings and equipment at Sendamachi and
Yagurashita, 6.700 and 900 feet distant from GZ,
respectively, were damaged sufficiently to be in-
operative. The extent of damage to buildings and
equipment is indicated on Table 1. Fires that fol-
lowed completed the destruction at Yagurashita,
but the existence of a firebreak north of Senda-
machi prevented the ignition of its buildings. The
converting equipment at Sandamachi was repaired
by 9 August 1945.
h. MAE for Buildinas. The buildings perti-
nent to this report, including installations and
equipment (‘Table 1), are classified by the building
damage section of this report. Any conclusions
for the mean areas of effectiveness (MAE) con-
tained in that section will apply also for buildings
in this section.
i. Damage to Rolling Stock. Of the 123 cars
operated by the company, 25 were damaged by fire
and 56 by blast. Of the 85 motor buses, 18 were
damaged by fire and 22 by blast. Cars and buses
within a radius of 1.500 feet of GZ were ignited
by radiant heat. Because of the nonuniform dis-
tribution of the cars and buses no attempt has
been made to calculate MAE’s. Maximum and
minimum radii for total, heavy, and slight damage,
however, have been drawn graphically on Figure 4.
j. Damage to Overhead System. Blast and fire
damaged 11.4 miles of the overhead transmission
system which included 500 wood and 100 steel
poles. No damage occurred to concrete poles, the
nearest of which were 6,000 feet from GZ. Wood
poles were damaged at a maximum distance of
4,500 feet from GZ, and steel poles, 3,500 feet.
Overhead transmission cable was blown down by
blast at 8,000 feet from GZ. The steel-rail pole
(Type 2, Fig. 3) or its equivalent seemed best
suited to support an overhead transmission system
for street railway transportation, rather than wood
or latticed-steel poles, as a protective measure
against an attack of this type.
k. Damage to Bridges. With the exception of
the bridge crossings (‘Table 5), no damage occurred
to the track system. Since the bridges referred to
in this section are covered by the Bridge Damage
Section, all data in connection with damage to
bridge crossings will be found in Section XII of
this report.
2. The System
a. The locations of all buildings, substations,
and overhead systems of the Hiroshima Electric
Railway Co., Inc., are indicated on Figures 1 and
13224 . = D
, Ps
' HIROSHIMA
CITY ELECTRIC RAILWAY AV A
'2es Ao fj = =
ie AND BUS SYSTEM (AN EN ATONE 1 9 SP
Wb DAMAGE RADII
LEGEND _/._ LIMIT OF BLAST DAMAGE TO OVERHEAD CABLES (8000)
2 DAMAGE TO GARS POLE TYPES LIMIT OF FIRE DAMAGE TO TYPE | POLES (6500')
(/~s —S—— LIMIT OF BLAST DAMAGE TO TYPE! POLES (4500))
TOTALLY BURNED § 22 TYPE |—WOOD POLES IN " BE may LIMIT OF BLAST DAMAGE TO TYPE 2 POLES (3500')
HALF BURNED 5 3 TYPE 2-STEEL RAIL OTS / 7 LIMIT OF BLAST DAMAGE TO TYPE 4 POLES (3000)
SEVERE DAMAGE a 23 TYPE 3~ LATTICE STEEL Bp / TIN TLD VY EG> LWA RY Vals 6S
MODERATE DAMAGE _—_ & 24 TYPE 4 - BUILT-UP MEMBER D) eel PTT TL . 7 a, |
SLIGHT DAMAGE 8 36 TYPE 5—CONGRETE POLES LAT rt irae
NO DAMAGE 0 1S —(I2 ON MIYAGIMA LINE) "7 hm lag Ss rd
' WY
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d\ DAMAGED OVERHEAD TROLLEY LINES —_ —______. a
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FIGURE |-XII
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149
Tape 1-XIII.—Hiroshima city electric railway and bus system buildings—building data
{Areas in thousands of square feet]
Rg oe) _ Equipment damage
Build- | Build-| Dis- | potar : Ss
Building Grid Usage Type = Stories ine Ane. Se floor | struc. Super-
HE-V Vv (fect) | 878 | tural | ficial | Per- anes
damage) damage} cent
(blast) | (blast)
OMOGS 2 cewannnakeceanw dD 7.0 2 V4 © 6, 700
Substations. ........--.. A2,3 3.0 1 v4 oO 6, 700
Repair shop... dD 6.0 1 V4 Cc 6, 700
D 2.8 1 V4 C 6, 700
Blacksmith shop._...__- dD 2.3 1 v4 Cc 6, 700
Paint shop............-- dD 3.9 1 V4 Cc 6, 700
Carpenter shop. —....-- dD 1 Br « 1 V4 C 6,700
No. 1 car barn__..__._..- D 91 1 v4 © 6, 700
No. 2 car barn_....... dD 5.3 1 v4 Cc 6, 700
Dressing room. -._..._.. Db 1.1 1 V4 Cc 6, 700
Warehouse dD 1.1 1 v4 Cc 6, 700
Rest room... dD Ep 1 V4 C 6, 700
Offios: ....<.< dD 11 1 V4 10] 6, 700
Rest! P00... <.......0- D 4 1 V4 Cc 6, 700
Bus work shop. ..-....-- Db 6.8 1 v4 Co 6, 700
INGo 1 WAYOGRS soos acean D 5.3 1 va Cc 6, 700
ING. 3 GOrASO. 08 oceans dD 5.3 1 v4 Cc 6, 700
Dining hall. ............ D 3.1 1 v4 Cc 6, 700
Nightwatch............- D -5 1 V4 Cc 6, 700
Pei, i a 2 8) 4.7 1 V4 Cc 6, 700
OMGS- oa oanxeksenceass dD 5 2} V4 C 6, 700
Warehouse. __..-....__.. Db 2.5 1 V4 c 6, 700
abe AOianns Heeesateo ana’ D Li 1 v4 Cc 6, 700
Bes ea F2 a 2| V3A Cc 6, 700
Olt sth GOs o 25nd s5u08 D .5 1 v4 Cc 6, 700
Bath house.............. D 6 1 Va C 6, 700 : ‘
Yagura Shita Station...| 7H | Substation ...........-- A2,3 3.8 1 va Cc 2, 200 3.8 “d)) eee 100 | Fire and blast.
mainder being a Japanese section approximately
90 pounds per yard, manufactured by the Japan
Rail Co., Kyushu. The rails were mounted on
8- by 8-inch ties, 7 feet long. The track gage was
4 feet 8.5 inches, measured between inside faces of
rails. As shown on Figure 1, the city proper was
built on a delta formation which necessitated a
number of bridges to complete the track system.
Table 2 lists bridges required for river crossings.
(Data are taken from Bridge Damage Section of
this report.)
TABLE 2.—River crossings
Bridge | Grid Length
Type (feet) Ownership
4 SJ | Reinforced | 246.5) City of Hiroshima; Electric Rail-
concrete. way Co.
13 51 | Steel T-beam 297.0 | Hiroshima Electric Railway Co,
17 7H | Plate girder....| 644.0 | City of Hiroshima; Electric Rail-
way Co.
24 |4G-H |__...do..._-....) 398.0 | Preferred Government; Electric
A Railway Co.
28 3Q | Timber.-.-..... 224.0 | City of Hiroshima; Electric Rail-
way Co.
35 5G | Steel I-beam___| 231.0 | Hiroshima Electric Railway Co.
44 4F |_....do. - 426.0 Do.
47 fy ee Se 351.0 Do.
150
In the case of jointly owned bridges an agreement
was made to facilitate construction and mainte-
nance, and to reduce the initial cost to each agency.
3. Analysis of Damage
a. The following terms and definitions for build-
ing and equipment damage have been used
throughout this section :
(1) Building.
(a) Structural: Damage to principal load-
carrying members (trusses, beams, columns, load-
bearing walls, floor slabs in multistory buildings)
requiring replacement or external support during
repairs. Light members, such as purlins and
rafters, are not included,
(b) Superficial: Damage to purlins and other
light members, stripping of roofing and non-load-
bearing exterior walls. Damage to glass and in-
terior partitions not included.
(c) Minor: Damage to glass and interior par-
titions, floor surfaces, and interior trimming.
(2) Machinery, utilities, and equipment.
(2) Total: Not worth repair.
(b) Heavy: Requiring repair beyond capacity
of normal maintenance staff; usually returned to
manufacturer,
(¢) Slight: Requiring repair within eapacity
of normal maintenance staff.
6. Of the 26 buildings (Fig. 2) which consti-
tuted the Sendamachi station, 6,400 feet from GZ,
only Buildings 2 and 24 were usable after the
atomic-bomb attack. The remaining structures,
Which were of wood-frame and timber construction
as indicated on Table 1, suffered structural dam-
age from blast (Photos 1 and 2). Since no fires
started in the Sendamachi area, all damage was
the result of blast. A firebreak immediately north
of the area prevented the spread of fires to the
south and to the Sendamachi area. The Yagura-
shita station, which was in another section of the
city (Fig. 1) was structurally damaged by blast
and fire, Buildings 2 and 24 of the Sendamachi
Station and the Yagurashita station are listed as
Buildings 35A, 35B, and 3, respectively, in Section
X, Damage to Buildings. The extent of damage
to the remaining structures is given in Table 1.
e. In order to resume business, a single room in
Building 1 was salvaged and used as office space
but, it being insufficient, cars that had been re-
Paired were utilized temporarily as additional
Space,
d, Because of the extent of damage to the street-
railway and motorbus-repair units and ware-
houses, repairs to rolling stock were curtailed
from 50 to 10 cars and from 25 to 5 motorbuses
per month.
e. Equipment damage (Photo3) in the converter
Station at Sendamachi was slight. Busbars and
electric distribution panels were damaged by either
blast or falling debris, but the converter equipment
Was not short-circuited either by debris or the sud-
den power cut-off. Damage to the Sendamachi
electric substation, which provided electrie power
for the converter station and the adjoining vicinity,
interrupted electrical distribution in the section.
By 9 August 1945, the converter station at Senda-
machi was repaired and operative, the 22-kilovolt
lines being shunted around the Sendamachi elec-
tric substation, and a direct connection made to the
city railway converter station. This action was
possible because of the subsurface circuits to the
Sendamachi electric substation. Both converters
Were available for use, but one was suflicient to
operate the cars on the portion of track which was
not damaged,
7. The Yagurashita station equipment, 900 feet
151
from GZ (Photo 4), suffered total damage by blast.
and fire. No equipment was salvageable.
g. Of the 1238 cars operated by the company, 99
were in use at the time of the attack and 24 were
held in reserve at the Sendamachi station. Of the
85 motorbuses, 70 were being operated while the
remaining 15 were under repairs or in reserve. In
reporting the damage to rolling stock, the company
officials employed other terms and definitions than
those used in this report and the combination of
both are defined as follows under equipment
damage:
(1) Total: Not worth repair. Totally burned.
(2) Heavy: Requiring repair beyond capacity
of norma] maintenance staff; usually returned to
manufacturer,
(a) Partly burned.
(6) Severe damage: Suflicient damage to pre-
vent use of car, Damaged, collapsed framing;
burned-out or damaged motive equipment,
(3) Slight: Requiring repair within capacity
of normal maintenance staff.
(a) Moderate damage: Sufficient to prevent use
of car temporarily-damaged seats and damaged
motive equipment that could be readily repaired.
(4) Slight damage: Insufficient to prevent use
of car—broken windows, displaced seats, but no
damaged motive equipment.
The number of damaged and burned cars is shown
on Figure 1. A summary of damage for both cars
and motor busses (Table 3) follows:
TaRLE 3.*—Damage to cars and buses
OPERATING AT TIME OF BLAST
came hy Damage by blast
Type of vehicle = < ee 7
ahi cavy | Heavy | Moder-
(totally | (partly | 2eavy | Moder) shone
burned) bamed) (severe) | ate :
Cerise: eoek de 22 3 13 16 3
Motor buses. 18 3 2 3 5
AT THE SENDAMACHI STATION
ee eee S| eee 10 8 6
Motor buses. 22224. 5/25 be]. 2-2 c 5 4 3
“Japanese classification.
Of the 15 undamaged cars, 12 were operating on
the Koi to Miyajima line; the remaining 3, at 10,-
800 feet from GZ, were protected from the blast by
buildings. The 42 undamaged motor buses were
also operating in outlying vicinities. Railway of-
ficials stated that cars and buses operating within
a radius of 1,500 feet of GZ (photo 5) caught fire
immediately on the side facing GZ. Observations
were made of damage to cars and buses within
the 1,500-foot radius. Evidence of ignition by
radiant heat was found in a fire lane along the
tracks where burned cars had been blown by blast,
substantiating the statements of the railway of-
ficials. Cars and buses were blown 30 feet, in
some instances, from where they were originally
standing. Buses adjacent to buildings were dam-
aged by falling debris. This was especially true
of both cars and buses that were standing in the
Sendamachi station (Photos 6 and 7). Rolling
stock that was burned outside the 1,500-foot radius
was ignited by adjacent burning buildings (Photos
Sand 9). Buses were totally damaged 4,000 feet
from GZ, and heavily damaged 5,500 feet from GZ.
Damaged cars and buses standing in the roadway
were removed and placed on side areas in order to
facilitate traflie (Photos 10, 11, and 12). The 42
available motor buses permitted some passenger
traffic to be maintained. By 9 August 1945 the con-
verter station at Sendamachi was again in opera-
tion and 8 cars were available for use, excluding
12 cars routed to Miyajima.
A. The traffic within Hiroshima for the month
of October 1945 was 800,000 passengers, and 500,-
000 were carried on the Miyajima line, which in-
dicated a decrease of 81 percent in traflic rate for
Hiroshima, and a 38-percent decrease for the
Miyajima line. Because of the reduced speed and
small number of cars, the allowable capacity of
the large cars was raised from 160 to 200 passen-
gers. Bus capacity was also raised approximately
50 percent.
7, Because the cars and buses were distributed
through the city in a nonuniform manner (i. e.,
many were concentrated in car barns), it was felt
that a calculated MAE would have no real signifi-
cance, Therefore, a graphical method was chosen
for presenting both the actual location of each
unit at the time of the atomic-bomb explosion, and
the extent of damage suffered by it. Figure 1
shows. the location of each unit at 0815 hours on
6 August 1945, the time of the attack. Figure 4
presents graphically the number of units suffering
damage in each of the three categories, total,
heavy, and slight, giving the maximum and mini-
mum distances at which such damage occurred.
No minimum distance is given for total damage,
152
as an examination of the diagram indicates the
likelihood that any unit within 2,300 feet of GZ
(the minimum distance for units suffering less
than total damage) would have suffered total dam-
age. Street railway cars were totally damaged
up to 6,700 feet and heavily damaged up to 8400
feet from GZ; buses suffered total and heavy dam-
age up to 4,000 feet and 5,500 feet from GZ,
respectively.
j. Of the 15.5 miles of railway system, 11.4 miles
of overhead transmission were heavily or totally
damaged (Fig. 1) directly as a result of the blast
or by fires subsequent to the blast. Results of a
survey by the company, accounting for 500 wood
poles and 100 steel poles damaged by fire and blast
(Photos 15 through 21) owned by them are shown
in Table 4, giving the maximum limit of damage.
Tarte 4.—Damage to poles
Damage (distance in feet
from GZ)
Type of pole Material is a
Blast Burned Tilted
Type 1 Wood___- 4,500 | 6,500 > 7, 500
Type 2 Steel rail__— rg ae | a8
Type 4 Built-up pole 3, 000 |.---.--| 3,500
Type 5 Conerete _ _- = ce :
Type 3 poles were owned and maintained by the
Chugoku Electric Co., but the Hiroshima Railway
Co. was allowed the privilege of overhead attach-
ment because of the joint agreement previously
mentioned, The steel-lattice poles were bent at
the base by the force of the blast at 6,000 feet from
GZ (Photo 22). The concrete poles at 6,000 feet
(Photo 23) from GZ were undamaged. Although
poles were intact and standing, the overhead cable
was blown down by blast 8.000 feet from GZ
(Photo 24). Some new poles necessary to operate
the portions of the system in use were installed,
and the partly damaged poles were utilized. ‘The
whole system was of a temporary nature and re-
placement of the majority of the overhead lines
would have been essential for continued opera-
tions.
i. No actual damage to the track system, except
at bridges, could be determined either by the rail-
Way company or by the members of the team.
Bridge 13 (Photos 25 and 26) was depressed ap-
proximately 20 inches, preventing traflic over the
Kyobashi River. Bridge 24 was subjected to a
PHOTO 1-XIII. Blast damage to offices and adjacent buildings at the Sendamachi substation,
6,400 feet from GZ.
PHOTO 2-NIII. Blast damage to warehouse at the Sendamachi substation.
153
PHOTO-3-XIII. Converter equipment at Sendamachi Substation, 6,400 feet from GZ.
PHOTO-4-XIII. Damaged converter equipment at Yagurashita substation, 900 feet from GZ,
154
PHOTO 5-XIII. Damage to car at an intersection 1,000 feet east of GZ. Damaged car to left;
others are in operation.
PHOTO 6-XIII. Damage to buses at the Sendamachi substation 6,400 feet from GZ.
731568—47 11 155
PHOTO 7-XIII. Damage to cars in car repair unit at Sendamachi substation, 6,400 feet from GZ.
PHOTO 8-XIII. Damage to car 2,000 feet southeast of GZ.
156
PHOTO 9-XIII. Damaged ear 4,000 feet northwest of GZ.
ee nee
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PHOTO 10-XIII. Damaged car 2,000 feet east of GZ.
157
PHOTO 11-XIII. Damaged bus 2,500 feet east of GZ.
PHOTO 12-XIII. Damage to car 3,000 feet northeast of GZ.
158
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PHOTO 13-XIII. Blast damage to pole and ear 4,000 feet southwest from GZ.
159
PHOTO 14-XIII. Blast damage to cars 9,000 feet southwest of GZ. Because of the extent of damage to the overhead
transmission system in the Eba area (Fig. 1) no effort was made to put this section of streetcar line in service and con-
sequently return the cars in the above photograph to Sendamachi for repairs.
160
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PHOTO 15-XIII. Blast damage to steel poles, 600 feet from GZ, and wood pole replacements.
PHOTO 16-XIII. Wood poles broken off at ground by blast 600 feet from GZ.
162
PHOTO 17-XIII. Blast damage to poles 2,000 feet west of GZ.
PHOTO 18-XIII. Bent steel and fractured wood poles 3,000 feet southeast of GZ.
163
r,
PHOTO 19-XIIi. Blast damage to wood and steel poles 2,500 feet northwest of GZ
PHOTO 20-XIII. Damaged cross arms 3,000 PHOTO 21-XIII. Blast damage to steel pole
feet west of GZ. 3,500 feet from GZ.
164
PHOTO 22-XIII. Damage to steel poles PHOTO 23-XIII, Standing concrete poles 6,000
6,000 feet southeast of GZ. feet east of GZ.
wh)
LZ
PHOTO 24-XIII. Damaged overhead 8,000 feet southeast of GZ.
165
aul
j
=—=s«T" * ek bee ee
PHOTO 25-XIII. Streetcar Bridge (13) damaged by blast and flood, 4,700 feet from GZ.
PHOTO 26-XIII.
Temporary repairs to stabilize car tracks on Bridge 13.
166
PHOTO 27-XIII. East approach to Bridge 24 showing blast damage, 1,000 feet from GZ.
PHOTO 28-XIII. West approach to Bridge 24 showing displaced tracks.
167
SOPOT TTT Mma wsereseeeree ee
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PHOTO 29-XIII. Bridge 17 showing high water on 23 October 1945.
re
ee
.
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PHOTO 30-XIII. Flood damage at Bridge 35. Ferry transportation across the Temma-Gawa,
168
PHOTO 31—-XIII. Undamaged, street car over-crossing at Bridge 4, 6,500 feet from GZ.
PHOTO 32-XIIL Undamaged, street car over-crossing at Bridge 44, 5,300 feet from GZ.
169
severe depressive and rebound action that dis-
placed tracks (Photos 27 and 28) on the bridge.
In addition to damage attributed to the attack, the
severe floods of 17 September 1945 and 5 October
1945 damaged Bridges 28 and 35 (Photo 30),
Bridge 13 was also further damaged by floods.
The following (Table 5) is taken from Section
XII. Damage to Bridges, bound herewith, and
indicates the damage to bridges in each instance:
TasBLe 5.—Damage to bridges
. | Dist,
a i ie is Type Damage classification Cause
(feet)
|
| |
4) SJ | 6,400 | Concrete SOMES uaneseqokneee eee
13) S51 | 4,600 | L-beam Modert te... < scene Blast and
| | flood.
17 | 7H } 7,600 | Plate girder.| None_..............
24) 4H | 1,000 do SHON. access... . Blast.
28 | 3G | 4,500 | Timber Complete destruction. | Flood.
a5 | 5G | 3,200 | T-beam Mie ee | Do.
44) 4F | 5,300 _.do NONGA s2s5) ce asddndete..
47| 4E | 7,400 |... do iss teaveowescteey
Damage classification is as follows:
Complete destruction.— Complete destruetion of structure re-
quiring replacement of entire bridge or within 10 percent of all
spans or bents or both; damage requiring from 90 to 100 per-
cent replacement of spans and piers,
Severe damage.—Complete destruction of the major part of the
structure or such damage that would require replacement of
more than half of the spans or bents; damage requiring replace-
ment of between 50 and 90 percent of the spans and plers,
Moderate damage.-—Damage or destruction of whole or part of
spans or bents of structure that could be replaced or repaired in
a relatively short time, the amount of damage not to exceed half
of the entire structure, 1. @, damage requiring replacement of
between 10 and 50 percent of the spans and piers,
Slight damage.--Damage to portions of spans or piers of strue
ture that would necessitate a minimum of repair or replacement.
/, Because of damaged poles and overhead sys-
tem, the only portion of track usable after the
attack was that between the Sendamachi substa-
tion and Ujina, but by 12 September 1945 the sec-
tion between Koi and the Sendamachi substation
via Dobashi, Tokaichimachi, and Takanobashi
was placed in service. The Japanese army as-
sisted in these repairs in order to facilitate the
transportation of personnel. By 12 October 1945
the track system between Kamiyacho and the ter-
minal at the government railway station, via
Hachobari, Matobacho, and Hiroshimaekimae,
was operative but repairs to Bridge 13 had not
been completed until 1 November 1945. The only
portions of the track system not in operation were
those between Tokaichimachi and Yokogawa, Do-
bashi and Eba, Hachobari and Hakushima, and
Matobacho and Senbaikyokumae.
cates the progress of replacement.
Figure 1 indi-
The loss of
170
Bridge 35 during the flood period hampered trans-
portation only insofar that passengers had_ to
cross the river by ferry (Photo 30) or by other
bridges on foot, and take the shuttle between Koi
and the Temma River.
4. Recommendations and Conclusions
a. The Sendamachi station, which was 6,400
feet from GZ, received severe structural damage
by blast, but no fire damage. Buildings 2 and 24
(Table 1) suffered only superficial damage, while
the remaining buildings, which were poorly con-
structed, were structurally damaged. The con-
verter station at Sendamachi was only slightly
damaged, being housed in Building 2, and was
operative in a few days. The Yagurashita sta-
tion, at 900 feet from GZ, construeted of brick,
was structurally damaged by blast and fire. Thus,
dispersal of converter stations offered effective
protection against the attack.
b. The overhead transmission system main-
tained by the city electric railway system was par-
ticularly vulnerable to an air-burst bomb of this
type. The wood pole, or Type 1, although more
easily installed and replaced, proved more vul-
nerable to blast and fire than the steel-rail pole or
Type 2. Comparison of the amount of replace-
ment of both types of poles indicates that the type
2 pole, being more resistant to fire and blast, there-
fore requiring fewer replacements, is the more
practical. Replacement of the overhead conduc-
tors could be facilitated on this type of pole, and
a greater part of the system would be operative in
a shorter time. A subsurface system such as that
used in some cities in the United States to elimi-
nate an overhead transmission system appears to
be the best solution.
B. GOVERNMENT RAILROAD SYSTEM
1. Summary
a. Location. The Government railways of
Japan was the only railway system providing in-
tercity transportation for Hiroshima. It main-
tained the double-track roadbed called the Sanye
Main Line, as well as classification yards, repair
facilities, transit sheds, and complete station!
facilities at Hiroshima. A single-track roadbed
connected with Ujina, the only deep-water harbor
in this area, to provide rail to ship transportat jon
for military material and personnel to continent!
Asia and other theaters of operations, Transit
sheds and stations were also maintained at Ko!
and Yokogawa, intermediate points within Hiro-
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HIROSHIMA, JAPAN
FIGURE 6 Xm
731568 O - 47 (Face p. 170) No. 2
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PMIANEIO HOITAOO) meme
shima. Figure 5 shows all lines and stations. A
total of 8467 persons was employed by the Govern-
ment railways in the Hiroshima area prior to the
attack of 6 August 1945.
b. Trafic. The average passenger rate per
month was 1,824,960 persons; the average monthly
tonnage in freight handled was 9,300 tons, requir-
ing 620 cars. A total of 6,000 cars per month,
however, was shunted through the yards.
ce. Repair Facilities. The vepair facilities were
capable of repairing all engines, tenders, and cars,
with the exception of the electric cars which were
sent to Hatabe, near Kyoto.
d. Roadbed. The roadbed in the area was a
fill section with a gravel ballast, as shown in
Figure 5,
¢. Bridges, The San yo Line erossed the
branches of the Ota River to the north, thereby
limiting the number of over-crossings to four
major, and a number of minor bridges for vehicu-
lar traffie,
fe Building Damage. The majority of build-
ings within the classification and repair area (Fig.
7) which were bet ween the radii of 8,000 and 10,000
feet from GZ were damaged by blast, while those
in the station area (Fig. 6) between the radii of
5,800 and 7400 feet were damaged by fire. Table
8 indicates the extent of damage to buildings
within the Koi and Yokogawa area. All build-
ings in this report are classified by the Building
Damage Section, and any conclusions drawn
therein for the mean areas of effectiveness will also
apply to buildings included in this section. ‘There
was No repair-equipment damage in the classifica-
tion or repair areas,
7. Locomotive Pamage. ‘There was no damage
to locomotives other than glass breakage.
h. Car Damage. Of the 700 freight cars in the
Hiroshima division. 45 were damaged by fire and
46 by blast, wnounting to 13 percent of the total;
of the 91 passenger cars, 6 were damaged by fire
and 77 by blast. or 93 percent of the total; and of
the 16 electric cars, 6 were damaged by fire and 6
by blast, or 75 percent of the total. The maximum
limit of distance in which probable damage to
freight cars might occur was approximately 6,800
feet from GZ, but since 93 percent of the passenger
cars were damaged within the 6,800-foot radius
and 75 percent of the electric cars were damaged
at 6,500 feet, the maximum limit for passenger and
electric cars was beyond 6,800 feet from GZ. No
passenger cars were found beyond the limits stated.
731568—47-_12
171
7. Trackage and Bridge Damage. There was no
damage to trackage or bridge crossings. Com-
munications and signalling facilities were not
operative because of damage to the communica-
tions office in the station area.
j. Cost, The total cost of damage to the Gov-
ernment railroads as estimated on 15 November
1945 was 15,800,000 yen, or $3,950,000 at the 4-yen-
to-S1 rate of exchange.
hk. Casualties. Of the 8A67 persons employed,
198 were killed, 140 were missing, 934 were seri-
ously injured, and 1,195 sustained minor injuries.
2. The System
a. The locations of buildings and trackage of
the government railways systems for the Hiro-
shima District are indicated on Figures 5, 6, and
7, showing repair units, transit sheds, and passen-
ger depot.
6, The government railways, operating the bulk
of the railroad systems in Japan, provided all
freight and passenger transportation to and from
Hiroshima. As noted on Figure 5, the double-
track system known as the Sanyo Main Line skirts
the city ina semicircle. The classification yards,
repair yards, and passenger stations were part of
the system. In locating the tracks at the northern
part of the city the river crossings of the deltas of
the Ota River were reduced to a minimum number,
being over the Kyobashi, the Ota, and the Yamate
Rivers. Ujina, the only island with a harbor sufli-
ciently deep to accommodate ocean-going vessels,
was connected to the Hiroshima freight vards by a
single-track line to facilitate the embarking of
military personnel and matériel for continental
Asia. The average number of passengers trans-
ported per month in the Hiroshima district was
1,824,960, exclusive of military personnel.
Through the war years the average tonnage in
freight carried was 9,300 tons per month, requiring
620 freight cars, but a total of 6.000 cars a month
was routed through the freight yards.
e. Figures 6 and 7 indicate all the buildings
within the limits of the Hiroshima railroad freight
and passenger areas, including the roundhouses
and passenger stations. This was the main sec-
tion of the Hiroshima subdivision where major
repairs to engines, freight and passenger cars were
made. Minor repairs to electric cars were also
made at Hiroshima, but major repairs were per-
formed at the shops in Hatabe, northwest of
Kyoto. Since all locomotives in this area were the
coal-burning type, coal bunkers were necessary.
The Hiroshima division maintained 3 fueling
bunkers consisting of a 100-, a 120-, and a 150-ton
bunker, respectively. The output of the 3 bunkers
was 500 tons of coal per day. A 10-ton traveling
crane was used for coaling operations.
d. The printing office, passenger station, and
roundhouse were surveyed by the Building Dam-
age Section as Buildings 120, 121, and 126, respec-
tively. All the other buildings were classified as
wood-frame, commercial-industrial structures or
light-frame, domestic structures.
e. The largest locomotives in the Hiroshima
area were those classed as D51 and D52 series
which weighed 77 and 85 tons, respectively. The
tender for each type was the same and weighed
44.7 tons loaded. The drawbar pull could not be
obtained, but the maximum train consisted of 65
freight cars of various tonnages. The average
train consisted of between 40 and 50 freight cars.
TABLE 6.—Freight and passenger car sizes
Type of car N Al ga Copact y
Passenger cars:
DIGGS Soap eatisscasteess 35. 64 49. 64
Mindiiin <2$o< eos 5 ok 34. 00 38. 00
Hc eee ae vee an 18. 81 22. 81
Freight cars:
10 Cpa Secale oi a 27. 00 50. 00
Medhimes. 3-2-9 s2le6e 6. 00 18. 00
PG Se iene es be 4. 00 8. 00
f. All rolling stock was manufactured under the
supervision of the government railways agency.
The rate of repairs of all rolling stock at the Hiro-
shima district was as follows:
Tasie 7.—Repair data for rolling stock
. . . . . Rat f
The freight handled in the Hiroshima freight Type reapits per
* a . t!
yards, as mentioned in Paragraph 26, required the — __ peer
use of 48 locomotives per day. This figure in- : RaMs Hii an
. . . . rT y 4 n ~ ===
cluded through trains which were routed via Hiro- opomonives, Types DG) end. DF 18
hi The follow; Table 6) is bulati f Tenders for D51 and D52____- . 13
shima. 1e fo owing ( able 3) Isa ta u ation © Piidsenaed edtet\ =<. Si: Seer see f 40
passenger and freight car sizes in tons as given Freight ears...._.___..______..----------- 130
by the government railways office : as :
Taste 8-XIII.— Hiroshima government railroad system buildings—building data
KOI STATION
[Areas in 1,000's of square feet]
é Building damage (floor area) ——
dis- e
Build- | Build- Total —- — —
Bulld- Tepe | Plan tance
ing Grid Usage Type | grog | Stories a = AZ 4 Structural damage Damage | \yinor
. (feet) — dam- | Pet | Cause
. | cent
Blast | Fire | Mixed | Blast | Fire | *8¢
4E | Sresidences.............. D 3.2 1 v-4 Cc 7,800 S| cee ney a ee yo Ae, eee ae ee
4E | Quarters...............- p | 25 ri a 2 pao mf a |e) ee Fa 1 1 ES eas (aa
Ue || Btathoniese tees: eo A23 | 21.8 aves || Oe orsenel|) aie eS ages sgl came ica (en Daa
4E | Transit shed.............| 4 A23 | 17.5 1| v-4 | © | 7,800] 175 eee [SEE] (SSeS (ae
4E | Warehouse. .............) D 5.7 1} V-4 Cc 7, 800 Dee Uplate cal daee dl cacanns Et ee ae ee Ae |e |
YOKOGAWA STATION
3H | 7 residences... ..........- dD Sl ae ee V4 Cc 6, 300 Sy ee a Roe) oe [eo Ae ae eae (re
3H | Quarters...............-- cag ary (eon Ot) ed (2 ee ra 3) Capea | SR TORRY ROH jerae
$H | Station! _.............-.- A23 | 21.3 |_....... V4 |G: eee) sus oe) eee ea ee
3H | Transit shed. ._-.....--- D Eeelaaseres vV-4 Cc 6, 300 9 kee BE Face aces lob anabs loathed sennndtsconniccessi
3H | Warehouse. ......... D RAadiotens v4 Cc 6, 300 Ly Aes Tg ere Gece Sod en See ena
SEF || GHONOOE wnhqciuadndnbadoud A2.2 5.7 1] V-4 N 6, 300 Sg) ane Bene Seer 57
These figures include the repairs of electric pas-
senger cars which received only minor repairs at
Hiroshima. Government officials estimated that
approximately 60 locomotives, 91 passenger cars,
700 freight cars, and 16 electric railway cars were
172
in the Hiroshima vicinity at the time of the attack.
g. The stations at Yokogawa and Koi (Fig. 5)
which were also within Hiroshima constituted part
of the Hiroshima railroad division. Yokogawa
was the terminal point of the Kabe Electric Rail-
Way. Table § lists all buildings at the Koi and
Yokogawa stations. The garage building at the
Yokogawa station is identified as Building 75 in
the Building Damage Section.
A. The track system indicated in Figure 5 shows
all track within the Hiroshima vicinity, including
the classification yards, The Sanyo line, or main
line, was a double-track roadbed through the city,
“rossing the Ota River delta on the north side of
the city, while the roadbed to Ujina was single
w . La hl .
- ack. The crossings of the branches of the Ota
tiver were as follows:
=e Tape 9.—Bridge crossings
| = Pe : ma
: River Grid ras Bridge type |Spans pean Remarks
ong aI 9 | Plate girder. 7 489 | Double track.
me ---..| 3H | Seca | Seat ie) Do,
a f aG vi do 10 390 Do,
mle Stream | 3G il do 2 66 Do.
| Sees 5 | 2 do 10 450 | Single track.
The above data are taken from the Bridge Damage Section.
& There was also a number of crossings over
highways constructed of steel beams, approxi-
mately 20 feet in length. The track bed between
the Enko and the Yamate Rivers was built on a
fill Section averaging approximately 12 feet in
height. Figure 5 shows the detail of the roadbed
fill Section, complete with ties, rails, and communi-
ations system. The equivalent of a 100-pound-
per-yard rail, manufactured by the Japan Rail
Co. was used.
+ There were 8.467 persons employed by the
Zevernment railways at Hiroshima prior to 6
August 1945.
3. Analysis of Damage
nee be hs overnment railways printing office and
lis Passenger station indicated on Figure 6 were
ood as Buildings 120 and 121, respectively, by
meee Damage Sect ion. All the remaining
“gs on Figure 6, being residences, offices, and
ce classified as light-frame, domestic
and? FN This building aren was between 5,800
PR Feet from GZ, and the majority of the
as ®S Was damaged by fire (Photos 33 through
3D), Dune to the drop in pressure So ee ee
and lack of electricity for auxiliary pumps, little
Saw: be done toward stemming the fires in the
sg fr area. Roundhouse 1, which is listed as
Building 196 by the Building Damage Section, and
173
the warehouses, repair shops, and engine sheds
(Fig. 7) which were classified as wood-frame,
commercial-industrial structures were damaged by
blast (Photos 36 through 44). Roundhouse 1 re-
ceived only minor damage (Photo 45). This area
was between 8,000 and 10,000 feet from GZ. Be-
cause of the disruption of power facilities at the
Dambara substation from which the railroad elec-
trical equipment was supplied, no electrical power
was available. Bunkers, cranes, and pedestrian
overcrossings were undamaged (Photos 46 and
47), but lack of electrical power prevented the
coaling operations of the cranes. When electrical
power was restored on 9 August 1945, coaling serv-
ice was resumed, and repairs in the roundhouse
were continued.
6. Figures 6 and 7 show the locations of pas-
senger and freight cars on the morning of 6 August
1945. At that time there were 91 passenger cars
and 125 freight cars in the passenger station area,
as shown on Figure 6, and 486 freight cars in the
classification area, as shown on Figure 7. All
damage to both passenger and freight cars in the
passenger station area was caused by blast and by
fire from adjacent burning buildings. The over-
turned freight cars indicated on Figure 6 were the
result of blast, but government railroad officials
stated that no passenger cars were overturned.
This was probably due to the protection that the
passenger station (Building 121) offered, whereas
the freight cars were in more open areas. This
area is between 5,800 and 6,800 feet from GZ. No
freight-car damage was sustained in the classifica-
tion or repair area, according to yard officials, nor
was there damage to locomotives. In reporting
the damage to rolling stock the Government rail-
ways officials employed terms and definitions other
than those used in this report. The combinations
of both are defined as follows:
(1) Total: Not worth
burned.
(2) Heavy: Requiring repair beyond capacity
of normal maintenance staff, usually returned to
manufacturer or repair section.
(a) Partly burned.
(6) Severely damaged, cannot be used without
repairs by the repair section,
(3) Slight: Requiring repair within capacity
of normal maintenance staff.
(a) Moderate damage, can be used temporarily
but must be repaired by repair section for con-
tinued service,
repairs. Completely
PHOTO 33-XIII. Passenger station and shelter damaged by fire and blast, 6,300 feet from GZ.
PHOTO 34—-NIII.
Railroad printing building damaged by fire, 5,800 feet from GZ.
174
PHOTO 35-XIIL. General view of passenger station area showing bomb damage, 6,300 feet from GZ.
PHOTO 36—XIII. Roof stripped from transit sheds by blast. 8.500 feet from GZ.
PHOTO 37—-XII.
Transit sheds damaged by blast, 8,700 feet from GZ.
176
PHOTO 38-XIII. Superficial blast damage to transit sheds, 8,500 feet from GZ.
PHOTO 39-XIII. Engine inspection building damaged by blast, 9,800 feet from GZ.
177
PHOTO 40-NJII. Warehouses damaged by blast, 9,500 feet from GZ.
PHOTO 41—NIII. Office and warehouse damaged by blast, 9,100 feet from GZ.
178
é
"> ;
Let
PHOTO 42—-XIII. Classification and repair area, 8.500 feet from GZ, showing general damage.
PHOTO 43-XITI. Classification area. Buildings damaged by blast, 9,600 feet from GZ.
showing minor blast damage, 8,700 feet from GZ.
PHOTO 45-XIII. Roundhouse,
181
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Nae a a
UP 2 SIP S27 be 2
PHOTO 46—NIII. Undamaged coal bunkers and crane on southside of Roundhouse 1, 8,900feet from GZ,
RAN
PHOTO 47-XIIT, Undamaged pedestrian over-crossing south of passenger station, 6,900 feet from GZ.
182
PHOTO 48-XIII. Yokogawa station area showing fire damage 6,000 feet from GZ.
183
(6) Slight damage can be used; repairs made by
train crew.
All car damage is summaried as follows:
Tasie 10.*—Passenger and freight or damage
| gem Fed Damage by blast
Type of ear ery ee aa Loe ee ee
Tota eavy | Heavy | Moder- ;
(totally | (partl oe ling . Slight
burned) Darnee y | Gevere)) ate
— |
|
Passenger cars:
Steel____- 4 8 12 20
Wood___- 2 15 2 20
Freight cars:
Steelisia2su5e 5 8 4
Wood...-..= 1 17 2
*Japanese classification,
c. All buildings in the Koi station area, 7,800
feet from GZ, received superficial damage. With
the exception of the garage (Building 75 of the
Building Damage Section), all buildings within
the Yokogawa area (Photo 48), 6,000 feet from
GZ, were destroyed by fire. Information was not
available from the government railroad officials
regarding the collapse of structures by blast prior
to the burning. Damage to buildings in the Koi
and Yokogawa station area is shown on Table 8.
d. At the time of the attack, train 377 was pro-
ceeding toward Bridge 9 over the Enko River.
The train was made up of 49 miscellaneous freight
cars and a locomotive of the D51 type. When the
locomotive had crossed 300 feet of the 490-foot
bridge the blast wave reached the train. Of the 49
cars, 10 on and 24 off the bridge were completely
.
184
overturned, or were off the tracks and tilted; also,
of 7 cars derailed but upright, 1 was on the
bridge and 6 off. The locomotive received only
broken glass damage, but the rear trucks of the
tender were derailed. None of the train crew was
killed, but minor injuries were suffered by a few.
The locomotive was disconnected immediately and
run to the west abutment of Bridge 9. It was re-
ported by the train crew to railroad officials and
to members of the team that fire broke out im-
mediately as a direct effect of the bomb in the first
5 cars behind the locomotive, which were still on
the bridge, as well as the 23 cars on the fill section
(Photos 49 and 50). The only evidence of fire
damage to the bridge consisted of slight irregular
charring of a few wooden ties. Table 11 relates to
the damaged cars and contents, as told by govern-
ment railroad officials. It is supplemented by
Figure 8.
e. It is felt, after examination of all cireum-
stances, that no fires could have been started within
the cars or to the cars themselves from radiant
heat of the atomic bomb, primarily because the
distance to the train was in excess of 5,800 feet
from GZ. The temperature was not high enough
nor of sufficient duration to ignite the cars or the
contents. The medical supplies in cars 45 through
49 could have combined into many different in-
flammable mixtures as a result of blast damage.
The remaining burned cars were in an area with
fires on both sides of the fill. It was therefore evi-
dent that those cars were ignited by the fires in the
area. The total number of cars—passenger,
freight, and electric—damaged at Koi, Yokogawa,
and at Bridge 9 is shown in Table 11.
PHOTO 49-XIII. Looking east at damaged freight cars on east end of Bridge 9, 5,800 feet from GZ.
14]
PHOTO 50-XIII. Looking west at damaged freight cars on east end of Bridge 9, 5,800 feet from GZ.
185
TaBLe 11.— Damage to Train 377
{0815 hours, 6 Aug. 1945 on Bridge 9]
a
No.
oe Type and No. Station from— Station to— Type of goods — Damage to ear Damage to goods Disposition of car
car
1 | Toki 7551.... | Saruiwa..._.....- No damage ....--- No damage. ._.---. Towed into station,
2 | Tora 7726 SE, ee ees _| Totally burned Totally burned _.
3 | Wa 1256 Shinagawa b Sak dscpeeae
4 | Tsu 5l4 FN ee ee a er i Pd eieeeet 1 1 aera Oot
5 | Wa 24922 Namitoi.__.. ee
6 | Tora 22655... | Yatsuo__-
7 | Sumu 486... Fukuda ‘Towed into station,
8 | Wamu 8572 sestld Do.
9 | Wamu 7527.. | Nakayamatera Do,
10 | Wamu 53055. | Osakawan Do,
11 | Tomu 20002 ..| Hisakawan _ ... Left in place,
12 | Toki 2705.....|----- 0... -cncennns.}-5--2€0_..5.2.2__--] Metalifubes.cnc.n] 0 969 nA O co eer antes aen=- nos catkins Do.
13 | Toki 1113_... | Rikuchijohashi.__- Slight damage Towed into station.
14 | Ho 89._..-.-. Meda. <2 5-2-- ==: _| Totally burned.
15 | WA 2409 ....do.
16 | Wamu 5008. | -...do wae
17 | Chiki 3625... | Anjikawaguehi - ; ..| No damage. _....-. Towed into station.
18 | Chiki 1167__. | Nejikawaguehi -- |.__-. Se ES ee | Ret) ee ene | Poe (ee See *
19 Sumu 1702. | Nakayamatera._- __.| Totally burned. _ | Totally burned.._| Left in place.
2) | Wa 23169... | Umegoro __.- _.| Moderate damage | No damage. ......| Towed into station,
21 | Wa 4147__... | Shibaura__- - . _.| Totally burned __| Totally burned. _| Left in place,
22 | Tora 3244... | Kameari Tsukinokawa____ | Miscellaneous... ..| ~~ _.| Severe damage... . ;
23 | Sumu 53148 __ Shita hs PS 2 ie ee Totally burned. ___
4 | Tora 40771... Wetoatas x. naan vuleseces ns BS eee || een a. (= ee
25 | Toki 3877__-. Minami-Kurume ~ ae. es eke
26 | To 7624 .... | Umeda Nakatsu......... Dion cote | ee Do.
27 | Tora 41733... | ....do Oita... b eae Ce?
28 | Sumu 2305. | Nijé _. DT Cs ee ee eS f a ae
29) Tamu 1194 Taketoyo Minami-Nobeoka_ eh nad Taaee loser aoe
30 | Tamu 1200. du CF CE EY Leal RNR Oe eR [Ma |) eae (eee
31 | Tora 8360 _...| Yatsuo Nishi-Hachiban__. Totally burned___. Do,
$2 | Sumu 53103 Fukuda 1 (| LR See “ No damage....---- Do,
33 | Wamu 27320._| Osaka ........-- 00) -dasacunene SOU ie gn PRREE,, " Seeeeee ee aemen Beem MGS comaeks Do,
34 | Wa 1891 Inasa Matsu-Shi- Medical supplies..| 1: |- Severe damage____|_---- (a an sf Do,
ma,
35 | Tomu 2190 Yasukuratera.___. PMs cass ceces 17 | No damage........|----- into station,
36 | Sumu 10127 Kusatsu __......- Miscellaneous __. 16 | Severe damage
37 | Tomu 24443.__| Ishiyama Torpedoes... ___. 18
38 | Wamu 25678. | Umegoro Medicines... _. 16
39 | Sumu 7854.._.| Hoshida Active charcoal. 16
40 | Wa 17704..._.| Kaizuka._. re th, COON rae oT 5,
41 | Wamu 51651__|__.. C.F eee ee ge) REBT, 7 euler ed (= ° ES | Reel meee y
42 | Sumu 87.__._.| Naka____- Aireraft parts... 15 Do.
43 | Wamu 28803._| Inasa___._- _.| Minimikurume___| Medicine Left in place,
44 | Wamu 25609._| Matsumoto. _____. Bic OO cwtesea soshon Do.
45 | Wamu 13472__|_____ do Tomitaka. ....----|-----
40) ) WROIATOR. ©. che doe oe ee 0025:
47 | Sumu 3546...) --__. do... rea. ta
48 | Wamu 1334.__| Sasashima. Omura____---
40 Wa 2870 ..| Takada Mizumakatera._-.-|-----
SUMMARY
- 1 a s
Type Boar | art | Gene | Mette | eh | wocamae | rou
186
SECRET
ILLUSTRATION SHOWING THE DERAILING LEGEND
OF FREIGHT TRAIN 377 BY THE ATOMIC = TURNED COMPLETELY
N —— Sa BURNED
Vjj~a OERAILED
« DERAILED AND BURNED
uJ
=
z BN
g
=
ul
APPROXIMATELY 147.5' APPROXIMATELY 285' APPROXIMATELY 1078'
as
Se,
oy
BRIDGE 8
SECRET
U.S. STRATEGIC BOMBING SURVEY
DERAILING OF FREIGHT TRAIN 377
HIROSHIMA , JAPAN
FIGURE 8 XII
731568 O - 47 (Face p. 186)
OF FREIGHT TRAIN 377 BY THE ATOMIC
BOMB
v
Towed
fou
Las
De
treed
rel EA i
sary
Le
ae
tren Bien af ee”
0 tal>
ihe atatéon
stalinm
“TABLE 12.—Damage to rolling stock in Hiroshima vicinity
Type of car
Damage by burning
Damage by blast
‘Total (totally
burned)
Heavy (partly
Heavy
urned)
(severe) Moderate Slight
Passenger car:
Steel
Freight cars:
Steeles ssp eee
Yokogawa
Bieel ss eo ea ek
Passenger cars:
Steel____-
Woodi=-...
Freight cars:
BiGAi doops Nes
WROGU ot weet»
Passenger cars:
Bridge 9___
Total
Electric cars:
Steel
to |
= 0
4
“Japanese classification.
As noted in Table 12, car damage at the Koi sta-
tion, ‘800 feet- from GZ, was negligible. The
Yokogawa station, however, being 6,000 feet from
GZ and in a fire area, received both blast and fire
damage,
f. In summarizing the total car damage in Hiro-
shima and vicinity, table 13 shows the percentage
of damage to rolling stock.
TABLE 13.— Percentage of damage to rolling stock
Type of car
On hand | Damaged | Percentage
Passenger... ? 91 83 92.9
Breight.< = 700 91 13. 0
Electric_ 16 12 75. 0
It is readily seen that passenger and electric cars
cars were the more vulnerable, probably because
of their construction.
731568—47——_18
187
g. In reviewing the damage to the rolling stock
by blast, since fires to rolling stock were generally
ignited by adjacent burning buildings, a maxi-
mum limit of probable damage can be determined.
The cars in the classification area within Hiro-
shima between 8,000 and 10,000 feet from GZ re-
ceived no damage, but about 50 percent of those
in the station area between 5,800 and 6,800 feet
from GZ received from heavy to slight damage.
In this area some empty cars were overturned. In
the Yokogawa station area, 6,000 feet from GZ,
the circumstances were the same but no cars were
overturned. However, at Bridge 9, which was
5,800 feet from GZ, 41 loaded cars were actually
derailed and 15 of the 49 cars were damaged by
blast. No information regarding blast damage
to the burned cars was received from railroad offi-
cials. In the Koi station area, 7,800 feet from GZ,
the damage to cars was negligible. From this it
can be concluded that the probable maximum limit
of damage for freight cars was approximately
6,800 feet from GZ. This conclusion was based on
the low percentage of freight cars damaged, the
majority of which were within the 6,800-foot
radius. Since passenger cars and electric cars
were damaged in a ratio of 93 percent at 6,800 feet
and 75 percent at 6,000 feet from GZ, respectively,
it can be concluded that the maximum damage
limit for these types extends beyond 6,800 feet
from GZ. No cars of these types were found
beyond that point.
h. There was no damage to the track system or
bridges (Photos 51 through 53). ‘The paint on the
steel girders of the bridges facing the blast, how-
ever, was discolored. All tracks of the Sanyo main
line were cleared at 1500 hours on 8 August 1945
and traffic was resumed. Between 6 to 8 August
1945 passengers routed through Hiroshima were
compelled to walk between Hiroshima and Koi
stations in order to make train connections. Sig-
nal systems were inoperative due to damage to the
communications office.
?. Traffic dropped off sharply following the at-
tack. Freight tonnage fell from 9,300 tons per
month to 5,400 tons per month, requiring only 360
‘ars. Repairs to rolling stock varied; repairs to
locomotives remained at 13 per month; freight cars
dropped to 60; while passenger-car repairs were
increased to 48 per month. Loss of freight traffic
rendered freight-car repair less important,
j. The total cost of damage as estimated by the
Government railroad agency on 15 November 1945
was 15,800,000 yen or $3,950,000 at the 4-yen-per-
dollar rate of exchange.
k. Of the 8467 persons employed, 198 were
killed, 140 were missing, 934 seriously injured, and
1,195 sustained minor injuries. No information
could be obtained for passengers killed or injured
during the attack,
4. Comments and Conclusions
a. The damage to the railroad system in Hiro-
shima as a result of the attack was suflicient to dis-
continue the services of the system for a short time.
The buildings in the station area (Fig. 6) were put
out of service entirely by blast and fire, but the
buildings in the classification area (Fig. 7) were
not damaged sufliciently to disrupt operations.
Damage to the electrical substation supplying
power caused the disruption, but this condition
lasted only until 9 August 1945. The buildings in
the station area were, for the most part, of wood
construction and compressed into a small area.
188
The fire which eventually reached this area dam-
ged all the buildings, but did not damage nearby
buildings in the classification area because of the
intervening tracks. A fire, started in, or near, this
area would have damaged all the buildings more
seriously, and railroad service in or through Hiro-
shima would have been impaired for a longer
period of time. It is concluded that dispersal of
buildings for necessary repair and storage would
be effective protection against an attack of this
type. Smaller, complete repair units, independent
of each other, would, if dispersed, insure repairs
in case of damage to one of the units.
b. Freight cars, with a probable limit of damage
at 6,800 feet from GZ, in this instance had a lower
rate of yulnerability than passenger cars which
had a greater probable limit of damage as shown
by the percentage rates in Table 13. Since the
trackage system was on the surface there was no
effective protection for rolling stock against the
attack,
c. The communication office was damaged by fire
sufficiently to halt its operation, but the signal
towers, being well dispersed, received only super-
ficial blast damage. Since the efficient routing and
the safety of trains were entirely dependent on
these systems, it was obvious that consideration
should have been given to their protection. The
benefit of dispersal for protection against fire, as
shown in Paragraph 4a, has been proved by the
lack of fire in the signal towers.
C. ELECTRIC GENERATING AND DISTRIBU-
TION SYSTEM
1. Summary
a. Cost of Electricity. The Chugoku Electric
Co., which supplied the city of Hiroshima with
power and light, purebased all its electrical energy
from the Nippon Electric Co. at 2.50 sen per
kilowatt-hour. The Chugoku Electrie Co. in
turn sold it to the consumers at 11 sen per kilowatt-
hour for lighting, 6 sen per kilowatt-hour for
heating, and 4 sen per kilowatt-hour for motor
energy. The total consumption per day was
80,000 kilowatt-hours for lighting and 170,000
kilowatt-hours for heating and motor energy,
b. Capacity of System. The Nippon Electric
Co. maintained and operated six hydroelectric
plants (Table 14) which had a total capacity of
94,200 kilovolt-amperes and one steam-electric
plant. of 90,000 kilovolt-amperes. These high-
tension systems were united at the Hiroshima sub-
a.
PHOTO 51-XIII. Bridge 9. Typical, double-track, railroad bridge, 5,800 feet from GZ.
_
ae
PHOTO 52-XIII. Typical railroad crossing over road, Bridge 8A, 5,600 feet from GZ.
189
PHOTO 53-XIII. Bridge 2. Typical, single-track, railroad bridge, 8,500 feet from GZ.
PHOTO 54-XIII. Type D51 series locomotive.
190
Station, rated at 108.000 kilovolt-amperes (Table
17), transmitted power to the Hiroshima Harbor
substation (rated at 12,000 kilovolt-amperes) on
the west side of Hiroshima, and distributed the
electrical energy through 7 substations in Hiro-
shima having a total capacity of 34,800 kilovolt-
“mperes (‘Table 17). The city of Hiroshima was
only a part of the area served by the Nippon Elee-
tric Co, The Chugoku Electric Co. also operated
* steam-electric plant rated at 3,500 kilovolt-am-
Peres to augment the Sendamachi substation. All
hydroelectric and steam-generating plants, as well
4s all substations, are located on Figure 9.
_ © Equipment. The generating and transform-
Mg equipment of both electrical companies was
Manufactured by the Nippon Electrie Co. The
design of all generating and transforming equip-
Ment originated with the Westinghouse Electric
Co. and the General Electrie Co. of the United
States, Design data were modified by the Japa-
hese to suit their requirements.
4. Buildings. The office building and substa-
Hon buildings are classified in Table 15. Build-
gs included in the building damage section are
shown in Table 16.
a? 28- and 110-Kilovolt Transmission System.
The Nippon Electric Co. transmitted all electric
Power from the hydroelectric plants to the sub-
Stations at 110 kilovolts. Power transmission
from the Saka steam plant was maintained at 55
ilovolts; this plant was approximately 4.5 miles
from the substation, Both the 55- and 110-kilo-
Volt high-tension lines were overhead systems.
They are located on Figure 9.
A - 33- and 22-Kilovolt Distribution System.
The Substations of the Chugoku Electric Co, trans-
formed 29 kilovolts down to 3.3 kilovolts for con-
sumer distribution. The Toyo Industries. Japan
“oundry, Hiroshima Electric Railway Co., and
the Mitsubishi Shipyard and Heavy Industries,
tOwever, having their own substations, received
pistes at 22 kilovolts and transformed it to re-
aii d voltages, Both overhead and subsurface
atveane for the 22-kilovolt distribution were em-
95 i : lhe overhead consisted of approximately
peace, eet of 3-phase system. The subsurface
‘sisted of 95,000 feet of 3-phase system with
ton mounted transformers for feeder distribu-
feng cations of the 22- and 3.5-kilovolt sys-
‘are shown on Figures 9 and 10,
9. Damage to Cquipment. The equipment in
the substations of the Nippon Electric Co. was
191
undamaged, being 15,000 and 14,300 feet from GZ.
Of the 7 substations of the Chugoku Electric Co.,
the Sendamachi substation and steam-electric _
plant at 7,700 feet from GZ were heavily damaged
by fires which spread to the area. The Otamachi
substation, 2,400 feet from GZ, was heavily dam-
aged by blast and fires started by the short-cir-
cuited equipment. The Dombara, Misasa, and
Eba substations were only slightly damaged at
distances from GZ of 5,500 feet and beyond. The
damage to the Sendamachi substation would have
been greatly reduced by adequate fire protection.
The remaining 2 substations were undamaged.
Table 18 summarizes the damage.
h. Damage to Buildings. Damage to the build-
ings of the Nippon Electric Co. and the Chugoku
Electric Co, is classified in Table 15. The build-
ings in Table 15 are classified in the building
damage section. Any conclusions therein drawn
for the mean areas of effectiveness for buildings
will also apply to this section.
i. Damage to 55- and 110-Kilovolt Transmission
Systems. The overhead 55- and 110-kilovolt trans-
mission systems were undamaged.
j. Damage to 33- and 22-Kilovolt Distribution
Systems. Approximately 70 percent of the 3.3-
kilovolt overhead and feeder distribution system
was damaged by blast and fire. Of the 7,000 poles
utilized, 4,000 wood poles and 27 steel-lattice poles
were damaged by blast and fire. No concrete poles
were damaged. Overhead wires were blown down
by blast 8,000 feet from GZ. (Table 19 gives the
limit of damage to the poles.) Of the remaining
undamaged 30 percent of the distribution system,
only 90 percent was usable because some areas be-
yond the points of damage could not be serviced
with electricity due to lack of connections to sub-
stations. The damage to the substations of Ote-
machi and Sendamachi made them inoperative and
the areas they serviced were distributed among the
other substations. There was no damage to the
22-kilovolt subsurface system.
k. Consumption of Power. By the end of Sep-
tember when the available 5 substations had be-
come operative, 40,000 kilowatt-hours per day were
used for lighting and 10,000 kilowatts per day for
motors and heating. This was an St)-percent over-
all reduction in the use of electricity.
1. Cost of Damages. The estimated cost of
damages to the Chugoku Electric Co. was 10,000,-
000 ven, or $2,500,000, at the 4-yen-per-dollar rate
of exchange.
m. Personnel Casualties. Of the 600 persons
employed by the company, 100 were killed, 100
were injured, and 50 were missing.
2. The System
a. The Chugoku Electric Co, supplied all elec-
trical power to the city of Hiroshima. Although
a subsidiary of the Nippon Electric Co., it con-
ducted all business as a separate agency, purchas-
ing its electrical energy from the controlling com-
pany. The purchase price of power from the Nip-
pon Electric Co. was 2.50 sen per kilowatt-hour.
6. In order to establish basic rates for the con-
sumption of electric power, separate classifications
were established based upon types of appliances
(lamps, heaters, and motors) and the scale of rates
was established in proportion to the amount of
energy used. The cost of energy to residents and
industry for each classification was 11 sen per
kilowatt-hour for lamps, six for heaters, and four
for motors. The average daily consumption of
electrical energy was 80,000 kilowatt-hours for
lighting, and 170,000 kilowatt-hours for heaters
and motors.
ce. As shown on Figure 9, the Nippon Electric
Co. maintained six high-voltage, hydroelectric gen-
erating units and one steam-electric generating
plant. Capacities for each unit and the total for
all units were as follows: :
TABLe 14.—Generating units
Capacity
(kilovolt-
Hydroelectric : amperes)
CUMANIO ane nr eee 24, 750
OS (ROCA SLES etn Oe Waa i aw re 10, 000
SHIMOFRMG SoS wren eee oe 18, 750
Ltr US a Se aoe os 15, 700
UMAR 6-3 ae Re Se ee ee 13, 750
Manohira 11, 250
TAS ETE lee Bs oN ae 94, 200
Steam-Electric :
OUST CTE ee 11] See te ee ee ed 90, 000
Grand total capacity_.__----------- ...-- 184, 200
The hydroelectric units and the steam-electric
unit generated power at approximately 12,000
volts. Because of the distances involved, voltages
from the hydroelectric units were transformed up
to 110 kilovolts for transmission, while the voltage
from the Saka steam plant which was approxi-
mately 4.5 miles from the Hiroshima substation
was transformed up to 55 kilovolts. The 3-phase
delta connections was used in all systems. The
Hiroshima substation of the Nippon Electric Co.,
which was the distribution point for all generat-
Tasie 15-XIII.—Hiroshima electric distribution system—building data
NIPPON ELECTRIC COMPANY BUILDINGS
[Areas in thousands of square feet]
Building damage (floor area) —
pean Ex S — ener ——
& i ct z Structural | Superficial
Building Usage Type = & S be damage damage Sine
. Nino!
g 2 a | 2 2 é I damage | =| Cause
~ Seer se & 3 z
2 gis/3/3/ 8 |2/2lel2| 3 le E
So a |am| a a a = Rim®lal & | & -¥
—_——_|-———- SS ee ee Se ae CS) Se ee ee ee ee ee ee SS
Hiroshima | 4M | Substation... S(E-1)....| 7.5 |2/3) V1 RG a) Se el eed Meee Seed Slight. .-.._.
BROS eee et ee Ores done gheouses 8(AZ,3)...| 2.5} 1) V4 Cc Ue ae ft ae ee ee Cs Oe
|
CHUGOKU ELECTRIC COMPANY BUILDINGS
Dam bara. ___- 5J | Substation....._..___- 8(AZ.3)..-| 1.3) 1] V4 8,200 | 1.3 |...... =| Deka Bees Pers Slight.......| 3 | Debris.
Suigenchi. iL aa a at Pe el ae ee Sedlankacolusnses FAS Fe sd ARe ae eane| Ie
Otemachi.__._- Oe] eee (Ee E-2.... | 3} V3] N wl! ee 50) Blast and
| fire,
Misasa. .._.... 3F “i. eye 8(AZ.3)..-| 1.6]} 1] V4 C vt) ee OY es Raa RS Reece) Se Moderate 10 Blast’
Sendamachi.._| 7 PRAORRMMN econ badass ote caadeesbctslecccts|snkelonnscdlanecen 3 a eee Ee ae aes Ped eee een 5 Blast and
fire.
Turbine building- —.__ 1) V4 Cc 8,000 | 7.6 " FG see! Eee ne 8 ones 80 Fire,
Boiler building. .__ 1| V4 Cc 8,000 | 5.0. 5.0 Do,
Nambu...._... 9H | Substation ._.....- 2| V4 ©: |) THON A Glce Se iwweldccelinte ces Sat
Ribas oc. 22ecce BPO NM saacOOiscccuaksocecesnn 1| V4 Cc 12,000) 0.4 G2 i5- ct leneas do 2 | Debris.
OMee..-. ft Pepe ne? eS a=
192
ow _N
KAZI SECRET Sy
/ UCHINASHI HIGH HEAD SHIMO YAMA
, HYD. POWER | cap 24,760 KVA HYD. POWER
As STATION STATION
NO KV 0 KV
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| ELECTRICAL GENERATING
AND
DISTRIBUTION SYSTEM
LEGEND
——— OVERHEAD WIRES
“=== UNDERGROUND WIRES
KUMAM
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STATION
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ing units, had a capacity of 108,000 kilovolt-
amperes and transformed down to 22 kilovolts
for use by the Chugoku Electric Co. The 12,000-
kilovolt-ampere substation at Hiroshima harbor
was also owned and maintained by the Nippon
Electric Co. The location of the generating units
and transmission lines are shown on Figure 9.
Hiroshima and its vicinity, as serviced by the
Chugoku Electric Co., was only a part of the area
supplied by the Nippon Electric Co. holdings.
d. The Nippon Electrie Co. used the Westing-
house Co, and General Electric Co. type for its
generating and transforming equipment with
modifications to suit Japanese requirements. All
equipment, however, was manufactured by the
Nippon Electric Co.
e. The Chugoku Electric Co. received all its elec-
trical energy ‘at 22 kilovolts and transformed it
to operating voltages by means of the 7 substations.
The Toyo Industries. the Hiroshima Electric Rail-
way Co., the Japan Foundry, the Mitsubishi Heavy
Industries, Mitsubishi Shipbuilding Co., and the
Mitsubishi Machinery Co., however, received
power at 22 kilovolts and transformed it down to
the Voltages required. There were also approxi-
mately 200 small industries which received elec-
trical power at 3.3 kilovolts. Office buildings and
dwellings, of which there were approximately
90,000, were supplied at usable voltages.
/. The substation buildings of the Nippon Elee-
trie Company and the Chugoku Electric Co. are
classified on Table 15. Although buildings were
used primarily to protect instruments, the Nambu
substation buildings was also used to house the
transformers, Transformers for the remaining
substation were placed in open areas adjacent to
the buildings, Since the Suigenchi substation was
without a building it utilized Building 6 of the
water-supply system for the protection of instru-
ments. The following buildings will also be
found in the Buildings Damage Section.
TABLE 16.— Buildings classified by Building Damage
Section
Building damage
Building: section building
Datibars. substation... <.-s--wan-necee eee | LT
SORA P I An intitititic] 3. < Gene ee 16
.-- 181A and 131B
ees!
Sendamachi substation__-------
Chugoku Electric Co. office-——.--
g. Table 17 indicates the capacities and voltages
of the substations of the Nippon Electric Co. and
the Chugoku Electric Co.
TABLE 17.—Substation capacities
NIPPON ELECTRIC CO. SUBSTATIONS (TOTAL 2)
‘ ‘ ., | Capac: | wich | y I
Substation Grid 7 it i side | Voltage side
Hiroshima___.__.._| 5M _ /108,000)110, 000). ___ _- 22, 000
68, 000i-—-2=< 22, 000
Hiroshima Ko___._| 6C |12, 000/110, 000). _____ 22, 000
CHUGOKU ELECTRIC COMPANY SUBSTATIONS (TOTAL 7)
Dambara_____- 5J 6, 000) 22, 000). - 3, 300
Suigenchi- - _ __ : II 1, 800) 22, 000) _ 3, 300
Otemachi- — — _- = 5H 6, 000, 22, 000) __ 3, 300
Minnea see52 l= - 3F | 6,000) 22, 000)__.__- 3, 300
Sendamachi_______| 7H | 3,000) 22, 000 3, 300
Nami. a. cocees 9H | 6,000) 22, 000). _.- 3, 300
PGi andadecasnss| POR 1G COR 22: 00015 _ sce 3, 300
Wothl=s i22s< bo St eae Se re a
According to the electrie company engineers, each
substation was designed at 6,000 kilovolt-amperes
to serve the equivalent area of a 9,800-foot radius.
With the exception of the substations at Suigenchi
and Sendamachi, all substations were rated at this
capacity. Due to the different densities of popu-
lation and industry, the areas were changed to fit
the demands. The Suigenchi substation was in-
stalled primarily to serve the city water supply at
Ushida, and, being in a sparsely settled area, 1,800
kilovolt-amperes were considered a suflicient
capacity. The Sendamachi substation had in ad-
dition to the transformer equipment a steam-elee-
tric plant rated at 3,500 kilovolt-amperes. Thus
the 3,000 kilovolt-amperes of the transformer
substation and the 3,500 kilovolt-amperes of the
steam-electric plant were combined to establish
the required capacity of that area. The trans-
formers and allied equipment, as well as the equip-
ment in the steam-electric Sendamachi substation,
were designed, manufactured, and installed by the
Nippon Electric Co. Figure 10 shows the location
of the 22-kilovolt and 3.3-kilovolt, high-tension
lines supplying the city of Hiroshima.
h. The transmission system of electric power
was divided into two classes: (1) The overhead
system, and (2) the subsurface system. The
former, consisting of approximtely 95,000 feet of
3-phase, 22-kilovolt overhead, was placed around
the outer rim of the city because of the danger
SECRET
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HIROSHIMA, JAPAN
FIGURE '2 XI
connected with a high-tension line of this type.
‘The towers for the 22-kilovolt line were approxi-
mately 110 feet high and designed to withstand an
overturning moment of 3,000,000 foot pounds.
Spacing of the towers was approximately 650 feet.
The 3.3-kilovolt system within the city, with all
leads to subscribers, required 6400 Type 1 wood
poles, 30 Type 3 steel-lattice poles, and 30 Type 5
concrete poles to complete the system. AIL poles
(Fig. 11) within the city carrying 3.3-kilovolt lines
were spaced at 150-foot intervals. All Chugoku
Electric Co. substations were interconnected by 3.3-
kilovolt lines. Approximately 600 pole-mounted
transformers stepped down the voltages for feeder
distribution.
i. The subsurface system consisted of 95,000 feet
of 200-ampere, 3-phase, lead-sheathed cable. All
subsurface cable, including subriver crossings, was
laid in reinforced-concrete ducts (Fig. 12), buried
4.5 feet below ground elevation.
j. Attempts to protect transformers from bomb-
ing attacks were made by the Japanese at some sub-
stations. Earth-filled wood forms varying from
2 to 4 feet in width were erected around the trans-
formers as protection against fragments.
k. The Chugoku Electric Company employed
600 persons for maintenance and operations. °
3. Analysis of the Damage
a. The Hiroshima substation (Photos 55, 56, and
57), 15,000 feet from GZ, was undamaged by blast
as a direct effect, but the tremendous overload
created by the short-circuited damaged electrical
equipment in the city of Hiroshima tripped the cir-
cuit breakers in this substation and immediately
interrupted all electrical service in the Hiroshima
area. Officials stated no damage occurred to the
equipment and no flash-over was noted. The Hiro-
shima harbor substation equipment (Photo 58)
was undamaged at 14,300 feet from GZ. After in-
vestigations by engineers the main substation was
in operation the day after the attack, while the
Hiroshima harbor substation, although undam-
aged, was not in operation until 26 August 1945.
This delay was due to the difficulty of making in-
spection in the area in which the 110-kilovolt
transmission lines were located.
6. The building of the Hiroshima substation
(Photo 57) received only minor damage, while the
Hiroshima harbor substation building was undam-
aged. Table 15 gives the damage classification of
the Nippon Electric Co. buildings.
ec. The equipment in the substations of the Chu-
196
goku Electric Co. at Suigenchi (Photo 59), 9,000
feet from GZ, and at Lambu (Photos 60 and 61),
11,500 feet from GZ, was undamaged by blast or
fire. ‘There was no evidence of heavy surges or
overloading in these substations, although elec-
trical equipment was damaged in the areas which
they supplied. These stations were inoperative
due to the power supply cut-off, but were again in
service on 9 August 1945. The equipment in the
Eba substation (Photos 62 and 63) the Misasa
substation (Photos 64 and 65) and the Dambara
substation (Photo 66), at 11,800, 5,500, and 7,900
feet, respectively, from GZ, received only slight
equipment damage. Two relays in the Eba sub-
station and 4 relays in the Dambara substation
were damaged by falling debris and overloading
of the circuits. The switchboard, including in-
struments, wiring, and other panel equipment in
the Misasa substation, was damaged by blast and
debris. The two relays in the Eba substation were
replaced on 11 August 1945, but the station was
not in operation until 20 August 1945 because no
power was being transmitted from the Hiroshima
Harbor substation until that time. The four re-
lays in the Dambara substation were not replaced
until September 1945, but the circuits were re-
wired to shunt out the relays, and the substation
was in operation on 9 August 1945. Because of
the difficulty of access to the Misasa substation,
temporary repairs to enable the substation to oper-
ate were not completed until 8 September 1945.
The substations at Otemachi (Photos 67 and 68)
and Sendamachi (Photos 69, 70, and 71) were sufli-
ciently damaged at 2,400 and 7,700 feet, respec-
tively, from GZ to put them out of service for an
indefinite period. The equipment at the Otemachi
substation (Photo 68) was dislodged by the effects
of the blast and was further damaged by fire
caused by short circuits in the equipment. The
substation at Sendamachi was heavily damaged by
fires originating in the areas adjacent to the sub-
station. Generator coils were burned out and the
switchboard totally damaged (Photo 69). Tur-
bine and generator bearings were also damaged.
Some distortion to shafting and turbine blades was
indicated. Boiler-room damage (Photo 71) was
confined to distortion of pipes and metal, but small
motors and pumps for collateral equipment were
heavily damaged. ‘The transformers (Photo 70)
were not damaged, but busbars and insulators re-
ceived slight damage and all leads to the trans-
forming equipment were totally damaged by blast
PHOTO 55-XIII. Undamaged Hiroshima transformer substation of Nippon Electric Co., 15,000
feet from GZ.
PHOTO 56-XIII. Undamaged Hiroshima transformer substation of Nippon Eleetric Co., 15,000
feet from’ GZ.
197
PHOTO57- XIII. Minor damage to office building. Hiroshima transformer substation of Nippon Electric
Co., 15,000 feet from GZ.
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PHOTO 58-XIII, Undamaged Hiroshima Harbor substation of Nippon Electric Co., 14,300 feet from GZ.
198
PHOTO 59—-XIII. Undamaged Suigenchi substation. Note transformer protection, 9,000 feet from GZ.
PHOTO 60—-XIIL. Undamaged exterior of Nambu PHOTO 61—XIII. Undamaged interior of Nambu
substation, 11,500 feet from GZ, substation,
199
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PHOTO 62—XIII. Eba substation. Building damaged by blast, 11,800 feet from GZ.
PHOTO 63—XIII. Panel of Eba substation. PHOTO 64—-XIII. Blast damage to Misasa
substation, 5,500 feet from GZ.
200
PHOTO 65—-XIII. Undamaged busbars and transformers at Misasa substation, 5,500 feet from GZ,
PHOTO 66-XIII. Dambara substation showing undamaged busbars and transformers, 7,900 feet from GZ.
291
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PHOTO 67-XIII, Blast and fire damage to Otemachi substation, 2,000 feet from GZ.
202
PHOTO 68-XILL. Equipment damage to Otemachi substation, 2,400 feet from GZ,
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PHOTO 69-XIII. Turbine and switchboard damage at the Sendamachi substation, 7,700 feet from GZ
31568—47 14 203
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PHOTO 70-XIII. Damage to exterior equipment at Sendamachi substation. Busbars being repaired.
Note that out-going lines are down,
PHOTO 71—XIII. Sendamachi substation boiler room damage. Boiler steel warped by heat and collateral
equipment damaged by fire.
204
and fire. Table 18 is a recapitulation of damage
to equipment in all substations owned by the Chu-
goku Electric Co.
TaBie 18.—Substation equipment damage
|
Substation Grid hom G PA Damage Cause
(feet) type
— i
Dambara..___ J 7,900 | Slight... Debris and overload.
Suigenchi. | IT} 9,000 | None...
Otemnchi.. SH |} «62,400 | Heavy.._.| Blast and fire.
Minna 3F | 5,800 | Slight.____| Blast.
eng ORD MORN C Tall SEES) |S ae ear
‘Turbo-Generators 7H 7,700 | Heavy ...| Fire.
Bollern ees scce 7H | 7,700 | Slight.....] Do.
Transformers | 7H 7,700 |...do......| Blast and fire,
Namba | oH 11,500 | None____-
Le 2 ee SE 11,800 | Slight. ....| Debris and overload,
The engineers of the Chugoku Electric Co. were
unable to give the approximate date when the Ote-
machi or Sendamachi substation would be repaired
and resume operations. Although the damage to
the tranformers and collateral equipment at the
Sendamachi substation was slight, little or no
effort was expended in placing the system in
operation,
@. Of the 7 substations and one office building
of the Chugoku Electric Co., the office building
(Photo 72) alone received structural damage by
blast. ‘The Eba (Photo 62), the Otemachi (Photo
67), Misasa (Photo 64), and Nambu (Photo 60)
substations were damaged to a minor degree only.
lhe Suigenchi substation (Photo 59) had no at-
tached building but depended on Building 6 of the
Purification plant (Part E of this section) for
housing its recording equipment. Damage classi-
fication of all substation buildings is given in
Table 15,
€. The substations of the Toyo Industries, Japan
Foundry, and the Mitsubishi Shipyards and In-
dustries were undamaged, being at distances
sreater than 15,000 feet from GZ. The damage to
the substations of Hiroshima Electric Railway Co.,
Inc., will be found in Part A of this section.
Sf. The 110-kilovolt, high-tension lines of the
“Ippon Electric Co. were undamaged, the nearest
PoInt of these lines being 11,000 feet from GZ.
- her © Was neither blast nor fire damage to the
~2-kilovolt overhead transmission lines (Photo 73)
of the Chugoku Electric Co., although the 22-kilo-
volt overhead lines which supplied the Misasa sub-
Station (Photo 74) were only 5,700 feet from GZ.
Approximately 70 percent of the 3.3-kilovolt over-
‘ead transmission lines and feeders, including
Pole-mounted transformers, was damaged by blast
205
and fire. (Nore.—In the following pages, photos
with an asterisk (*) will be found in Part A, and
those marked with a number sign (#) will be
found in Part C of Sec. XIII.) Of the 6,400 wood
poles (Type 1), 500 were broken by blast (Photos
*16, 76, 77, 78, 79, 80, 81, 82, and 84), and 3,500
were burned (Photos 82, 85, 87, and 88). Of the
30 steel-lattice poles (Type 3) 6,000 feet from GZ,
27 were damaged by blast (Photos *17, "19, *22,
76, and 77), having been bent at the base. No con-
crete poles (Photo *23) were damaged, the nearest
con¢rete pole being 6,000 feet from GZ. Overhead
transmission wires were found parted and down
8,000 feet from GZ as a result of blast (Photos *86
and *88). The limits of damage to the types of
poles of the Chugoku Electric Co. are shown on
Table 19.
Tasie 19.—Pole damage limit
Damage
io Material >= |
Blast (feet)} Pumed | Tilted
1 | Wood. 4, 500 7, 000 7, 500
3 | Steel lattice. : 6, 000
5 | Conerete_ - - - =
g. Of the 70 percent of the 3.3-kilovolt overhead
lines and feeders damaged, it was estimated that
10 percent could be salvaged for reuse with the
exception of the pole-mounted transformers
(Photo 75), which were totally damaged, requiring
100 percent replacement, The remaining 30 per-
cent of the overhead was only 90 percent operative
because the overhead transmission beyond the
points of damage could not be supplied with elee-
tricity due to the heavy damage in the Otemachi
and Sendamachi substations, The 3.3-kilovolt
lines in these areas which were undamaged were
divided among the adjacent substations, and sup-
plied with power by shunting around the Otemachi
and Sendamachi substations and interconnecting
with the other available substations. Figure 10
shows the extent of damage and replacement of
overhead.
h. The subsurface 22-kilovolt transmission sys-
tem was undamaged and consequently power could
be supplied immediately to the substations which
were operative. The 22-kilovolt subsurface lines
supplying undamaged facilities from the damaged
substations were shunted around those substations
and supplied by others.
PHOTO 72-XIII. Blast damage to the office of the Chugoku Electric Co. (Bldg. 26), 2,300 feet from GZ.
BS ENG tase:
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PHOTO 73-XIII. Conversion from overhead transmission system to subsurface system. Undamaged
at 9,500 feet from GZ.
206
PHOTO 74-XIII. High tension tower, 6,500 feet PHOTO 75-XIII. Pole-mounted transformer
from GZ, undamaged, damaged by fire, 200 feet from GZ.
PHOTO 76-XIII. Steel lattice and wood pole 2,000 feet from GZ,
207
PHOTO 77—XIII. Steel lattice and wood pole 2,000
feet from GZ. Framing members of Bridge 30A also
damaged at this distance.
PHOTO 78-XIII. Wood poles 3,000 feet from GZ. PHOTO 79-XIII. Wood poles 3,000 feet from GZ.
208
PHOTO 80-XIIL. Wood pole down at 4,000 feet from GZ,
PPOTO 81-XIII. Broken wood pole 4,500 feet PHOTO 82-XIII. Burned poles 4,500 feet from
from GZ. GZ.
209
PHOTO 33-XIII. Broken and replaced wood PHOTO 84—-XIII. Broken wood pole at 4,500 feet
pole 4,500 feet from GZ. from GZ.
PHOTO 85-XIII. Burned poles at 5,500 feet from GZ.
This area was 40 percent built up Burning of area
resulted also in burning of poles.
210
PHOTO 86-XIII. Tilted wood poles 7,000 feet from
GZ. Note flash burns and severe tilt away from blast.
PHOTO 87-XIII. Charred poles 7,500 feet from PHOTO 88—XIII. Scorched poles and wire down
GZ. 8,000 feet from GZ.
211
i. By the end of September 1945, when all avail-
able substations were in operation 40,000 kilowatt-
hours per day for lamps and 10,000 kilowatt-hours
per day for motors and heaters were being con-
sumed. This indicated a 50-percent reduction in
the use of lamps and 94-percent reduction in the
use of heaters and motors, or an 80-percent over-all
reduction in the use of all electrical facilities.
j. The estimated cost of damage to the electrical
power and light facilities on 15 November 1945
was 10,000,000 yen, or $2,500,000 at the 4-yen-to-a-
dollar rate of exchange.
k. Of the 600 employees of the Chugoku Elee-
tric Co., 100 were killed, 100 injured, and 50
missing.
4. Recommendations and Conclusions
a. The electrical generating, transforming, and
transmission equipment of the Nippon Electric
Co, and the Chugoku Electric Co. was on a stand-
ard comparable to that used in the United States.
This was not unexpected, since the design data
for the equipment of these Japanese firms were
supplied by the leading electrical companies of the
United States. Some modifications in the equip-
ment, however, were made by the Japanese. With
the exception of the Otemachi and Sendamachi
substations, the substation equipment successfully
withstood the effects of the attack. Had fires not
reached the Sendamachi substation at 8,000 feet
from GZ, it is believed that damage would have
been confined to equipment in the same degree as
that at the Dambara substation at 8,200 feet from
GZ (Table 15). If adequate fire protection had
been maintained in the Sendamachi substation,
damage would have been slight. Auxiliary pumps,
however, would have been necessary to protect
these vital utilities in case of power failure. Fires
in the Otemachi substation were caused by the
short-circuited equipment. Only one substation
which amounted to 15 percent of the substation
system was put out of service by blast and result-
ing short-circuit fires. ‘The remaining substations,
having suffered only slight equipment damage,
were operative wtihin a short time. From these
facts it is considered that with modern equipment
and normal fire protection 85 percent of the sub-
stations would be immune to an attack of this type.
6. With the exception of the office building of the
Chugoku Electric Co., which was structurally
damaged by blast, the substation buildings, being
well dispersed, received only damage extending
from superficial to slight, as shown on Table 15.
212
It appears evident in this case that dispersal of
substations was adequate protection, but these con-
ditions could be improved by the elimination of
combustible material in or near the structures.
e. The 110- and 22-kilovolt overhead transmis-
sion systems received no blast or fire damage, a
terminal of a 22-kilovolt line being at the nearest
point, 5,700 feet, from GZ. The 3.3-kilovolt lines
with the connecting feeders were particularly
vulnerable to an attack of this type, and approxi-
mately 70 percent of the transmission lines were
damaged. The Type 1 poles were damaged by
blast up to 4,500 feet from GZ and by fire up to
7,000 feet from GZ. The Type 3 poles were vul-
nerable to 6,000 feet from GZ. Since there was no
Type 3 poles farther than this from GZ, the limit at
which they could withstand the blast could not be
determined. Inasmuch as only 10 percent could
be salvaged from the 70-percent damage, a consid-
erable amount of replacement and repair to an
overhead system carried on Types 1 and 3 poles
could be anticipated from an attack of this sort.
d. Since the subsurface lines buried 4.5 feet be-
low ground elevation were undamaged, all 22-kilo-
volt lines were available for use. If costs were not
exorbitant, a subsurface system for lines of lower
voltages would be the best protection.
D. TELEPHONE COMMUNICATIONS SYS-
TEMS
1. Summary
a. Trafic. The Bureau of Telephones of the
governmental communications department admin-
istered and operated all telephone communications
within and through the city of Hiroshima which
was divided into two districts, the Central District,
which maintained a manually operated system and
had 5,500 subscribers, and the Western District,
which maintained a dial system with 3400 sub-
scribers. The average local traflic per month was
3,240,000 calls. Long-distance calls, averaging
435,000 per month, were routed through the central
district. Telephones and equipment were of
Western Electric design and Japanese manu-
facture.
b. Transmission System. The transmission sys-
tem consisted of both overhead and subsurface
lines. The Central District (Fig. 13) maintained
104,790 feet of overhead cable carried by 4,055
poles, and 30,232 feet of conduit-encased, subsur-
face cable. The Western District maintained
53,660 feet of overhead cable carried by 2,493 poles,
.
J} ‘ \ ? “s oF
DAMAGE RADII
HIROSHIMA
TELEPHONE COMMUNICATION
SYSTEM
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HIROSHIMA PREFECTURE, HONSHU, JAPAN
HIROSHIMA-KO
(HARBOR)
AN (BAY)
oh erry 1g
Sale 2
+ a i U.S. STRATEGIC BOMBING SURVEY
fe = i TELEPHONE SYSTEM
HIROSHIMA, JAPAN
FIGURE 13-XII
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and 9.770 feet of conduit-encased cable. All sub-
surface cable was buried 4 feet below ground ele-
vation, Intersections occurred at manholes, of
which there were 223. Because of the number of
branches of the Ota River, 18 bridge cable cross-
ings and 9 subriver crossings were necessary.
Subriver cable was buried 4 feet below river
bottom.
¢. Building Damage. The buildings of the Cen-
tral and Western District exchanges are treated
in the building damage section and are found in
Table 23. The initial damage to the equipment in
both exchanges was by blast. Fires from short
circuits totally damaged all equipment in the Cen-
tral District exchange, but new, enclosed-type
equipment in the western district reduced short-
circuit fire damage to 50 percent. All telephone
communications were disrupted.
d. Overhead Transmission System Damage.
Approximately 80 percent of the overhead system
was damaged by blast and fire; 97,280 feet of cable
and 4,551 wood poles being damaged in the Central
District, and 51.280 feet of cable and 2,293 wood
poles in the Western District. A 10-percent sal-
vage value was estimated. Wood poles were dam-
aged by blast at 4,500 feet from GZ and burned at
6,500 feet. Cable was stripped from hangers at
8,000 feet.
e. Bridge Damage. There was no damage to
the conduits and manholes carrying the subsurface
system. Damage to Bridges 6, 135A, 21,24, and 29,
however, as well as damage to cable exit points on
conversion to overhead, put approximately 80 per-
cent of the subsurface system out of service. By
15 August 1945, 35 pairs of subsurface cable had
been repaired and were available for use. All
bridge data are covered by the Bridge Damage
Section, and any conclusions drawn by that sec-
tion for means areas of effectiveness for bridge
will apply also for this section.
f. Subsurface Transmission Damage. The sub-
surface system at 4 feet below ground elevation
would have been intact if it had not been exposed
to exterior damage at bridge crossings and exit
points to the overhead system. Approximately 80
percent of the subsurface system was put out of
service, but the majority of the cable was
salvageable.
g. Cost of Damage. The estimated cost of dam-
age to telephone communications by the attack was
approximately 10,000,000 yen, or $2,500,000 at the
4-yen-to-a-dollar exchange rate.
213
h. Casualties. Of the 900 personnel employed,
350 were killed, injured, or missing.
2. The System
a. All telephone communications in Hiroshima
were under strict government supervision. The
telephone service was divided into two types, the
dial and manually operated systems. The Central
District, all that portion of Hiroshima east of the
Ota River, utilized the manually operated system,
having 5,500 subseribers serviced through Ex-
change Building 43. The Western District util-
ized the dial system, having 3,500 subseribers
placing calls through Exchange Building 85. In
addition, there was a relay station for interurban
service through Hiroshima. The local telephone
traflic within the city for both types of exchange
averaged 3,240,000 calls per month. All long-dis-
tance traffic was routed through the Central Dis-
trict exchange and via the Western District
exchange, if the call was placed or taken in
that district. The long-distance traflic averaged
435,000 calls per month. The locations of the
telephone-exchange buildings in the Central and
Western districts of Hiroshima City, listed as
Buildings 43 and 85, respectively, by the Building
Damage Section, and all overhead and subsurface
transmission systems of the Bureau of Telephones,
Governmental Communications Department, are
indicated on Figure 13,
}. The manually operated telephonic equipment
in the central exchange building was of the
Western Electric Co. type, manufactured by the
Oki Electric Co. Installation of equipment was
completed in 1920 by the same company. The dial
telephone equipment in the Western Exchange
Building was also based on the Western Electric
Co. type and manufactured by the Oki Electric
Co. which completed the installations in February
1940. Local.
1,200 | Conduit_- Do.
800 | _do- - Do.
600 Hdou! oe Do.
2, 000 x." eos : | Do.
Ad ‘ 100 |._..-do-__---_-___.-| Interurban.
100 | Overhead___--_- | Local.
se S| 2,000 | Conduit__-__- soe Do.
5, ee 600) |. ,.-=do-2: een Do.
SECRET
POLES FOR TELEPHONE COMMUNICATION
SPIRAL STEEL
APPROX. 2” PITCH,
\4" OUTSIDE DIAMETER AT BOTTOM
8’ OUTSIDE DIAMETER AT TOP
45' HIGH
15/8" x 15/8" x 1/8"
GALVANIZED &
1'- 8" AT BOTTOM
10" AT TOP ax 3x36"
\'-8" AT BOTTOM
45° HIGH
SIDE VIEW | CONCRETE FOUNDATION
——<—<<—— SS e-e'x2-8' x80"
SECRET
U.S, STRATEGIC BOMBING SURVEY
TELEPHONE POLES
HIROSHIMA, JAPAN
FIGURE 1|4-XII
215
SECRET
TELEPHONE COMMUNICATION SYSTEM MANHOLES
STANDARD ROUND BRICK MANHOLE
SECRET
TELEPHONE SYSTEM MANHOLES
HIROSHIMA, JAPAN
FIGURE |S XI
216
TABLE 23-XIII.— Hiroshima telephone communications system— building data
[Areas in 1,000’s of square feet]
Building damage (floor area) eae
7 Dis-
Build- | Build- Total
Baila. | Grid Usage Type — Stories} ing ing | ‘ance | foor Structural Super.
| HE-V | Fire-V (feet) area damage damage Minor Per- en
ae ——S- damage cent -
Blast) Fire | Mixed) Blast) Fire
43 | 5H | Telephone exchange.) El |_..... 2/3) Vi R rh os S| Dee Pe Power! Raed Pie Severe 100 | Fire.
85.| "eae oan eee El 3] vi 93600) tae oe ed i Moderate 50 | Mixed
2». |
section. Table 23, however, shows the extent of distance of 8,000 feet from GZ, but the poles were
damage to each building.
b. The equipment in the Central District (Photo
90) and the Western District (Photo 92) Exchange
Buildings, which were 2,800 and 3,800 feet, respec-
tively, from AZ, was initially damaged by blast.
Short circuits from damaged equipment started
fires that totally damaged the equipment in the
Central District Exchange Building. Eyewit-
hesses stated that the equipment was afire immedi-
ately after the explosion, corroborating a statement
made by the chief engineer of the Bureau of Tele-
Phones. Since the equipment was on the opposite
side of the building facing AZ, adequate protection
from radiant heat was afforded by the concrete
slabs. It was therefore concluded that short cir-
cuits were the cause of the fire, which was in agree-
ment with the Japanese. The equipment in this
exchange was of the old, open type and burned
freely: the Western District Exchange equipment,
being of recent manufacture, was enclosed and the
damage due to blast and short cireuit fires was re-
duced to 50 percent, but the damage was sufficient
to halt all telephone communications. Blast and
fire dest royed approximately 7,000 telephones.
c. The greatest damage to the telephone trans-
Mission system was in the overhead section (Photos
"16, *17, *18, *99, *23, and 94 through 98). The
Majority of poles, being wood, were downed by
last or were consumed by the fire that followed.
Lead-sheathed cables were totally damaged by
ve, being consumed up to the point of entry of
the subsurface system (Photo 93). Wood poles
(Photo #87) were broken off at varying heights
Up to 4,500 feet from GZ and were burned (Photo
#85) at a distance of 6,500 feet from GZ. Cable
(Photo 98) was stripped from the hangers at a
217
upright and the cable was otherwise undamaged.
Figure 13 indicates the extent of damage to the
overhead system and shows the distances to GZ.
Table 24 lists damage to the overhead transmission
system.
TABLE 24.—Damage to overhead system
Central dis-
trict (feet)
Western dis-
trict (feet)
No. of pairs per cable
200_ 5 Scie ct i) eee a
LOD eS raat sane e wie nenaae, 47, 850 23, 790
5022:; 29, 650 17, 180
| ke a ee 12, 600 6, 700
15 and under____-_- 2, 262 1, 320
Wood poles a 4, 551 2, 293
No concrete poles were damaged (Photo *23).
Approximately 80 percent of the overhead system
of both the Central and Western District was dam-
aged. The salvage value of the damaged equip-
ment and materials for the overhead systems was
estimated at 10 percent.
d, Upon examination of the subsurface trans-
mission system by officials of the Bureau of Tele-
phones subsequent to the attack, no damage to
manholes or ducts was found. Examination of
manholes by members of the survey revealed no
evidence of cracks, breaks, or other damage. A1-
though no actual damage was done to the subsur-
face system in itself, the damage to bridges (Photos
99 through 104) serving as overcrossings and exit
points on conversion to the overhead system put
out of service approximately 80 percent of the
subsurface system. Table 25 indicates the damage
to bridges as estimated by the Bridge Damage
Section.
PHOTO 89-XIII. Bureau of Telephones’ Central District Exehange Building showing damaged
equipment, 2,000 feet from CZ.
PHOTO 90-NIII. Equipment damage in the Central District Exchange Building.
218
PHOTO 91-NIII.
Bureau of Telephones’ Western District Exchange Building, 3,300 feet from GZ,
PHOTO 92-XIJI. Equipment damage in the Western District Telephone Building.
219
PHOTO 93-XIII. Telephone-cable transition from subsurface to overhead system damaged by blast and
fire, 1,200 feet from GZ.
Stripped cable 4,500 feet from
GZ.
PHOTO 94—XIII. Damaged wood pole and cable, PHOTO 95-XIII.
2,500 feet from GZ.
220
PHOTO 96—-XIII. Steel-lattice poles, 6,000 feet
from GZ. Poles were downed by blast across road,
but were removed to make way for traffic.
PHOTO 97-XIII. Damaged cable, 7,500 feet from PHOTO 98-XIII, Cable downed, 8,000 feet from
GZ. GZ.
221
TABLE 25.—Damage to overcrossings
Bridge Grid baoeth fem ‘ i Type
6 41 266-6, 100 | Timber __-
13A BLT), 2 B07) 4: 700Ne- = dons.
21 5H 295 1, 400) (2... dows... aed
24) 4G-H 398 1,000 | Plate girder--- —_-
29 5G 263 1,200 | Pin-connecting truss_.
Figure 13 shows the location of the damaged
bridges. Although Bridge 24 was not down
(Photos 103 and 104), the severe blast effects
parted the transmission cables. There was no
damage to subriver crossings. Thus, the several
types of damage put out of service the cables in
each district as given in Table 26.
Tapie 26.—Damage to subsurface system
Number of pairs per cable See tay: ye hog
1,200.5 3, 880 2, 540
800,---= ett 6, 350 1, 470
O00 Se 5 a5 Se Sue fet SEs Sas 6, 470 3, 250
rt (Oe epee Age bel aa ~ 5, 300 1, 200
GUL GE aerate arden eae lee Seki 1, 320 200
1O0n 6c tee odeeateconokceue 860 32
O0ict seta cae Cboe bon coset ce 1, 700 6, 666
Repairs and reconstruction began almost immedi-
ately and by 15 August 1945, 35 pairs of subsurface
transmission cables were back in service. These
were used entirely by the prefectural government
and Japanese military units. Since the equipment
in the Central District Exchange Building was
totally damaged, all telephone traffic was routed
through the Western District Exchange. With
the exception of the breaks at bridge crossings,
connections were remade in subsurface circuits.
By 30 August 1945, 50 pairs were available for
long-distance use with the following cities: Tokyo,
Osaka, Okayama, Shimonoseki, Fukasho, Iwakuni-
Beppu, Matsuama, Takamatsu, Zentsuji, and
Matsue Hamada. ‘Ten lines devoted to outlying
vicinities of Hiroshima. During the floods of
September 1945 and 5 October 1945, additional
serious damage was added to that suffered as a
result of the atomic-bomb attack. More bridges
serving as overcrossings were damaged, as given in
the following table:
Number
Extent of damage of pairs
| per cable
Cause of damage
| |
Blast and fire-____| Complete destruction —_ 100
Cage we 2S AOR: ao eae --| 1, 800
Blasts sfc: 4 Js rd eee __-| 1,000
_.do- Slight damage. ________ 800
....-do___.._...--| Complete destruction _- | 2, 000
TaBie 27.—Damage to overcrossings by flood
be
ro
Bridge| Grid | Length Type pairs | Extent of damage
(feet) per
cable
31 6H 358 | Concrete......... 100 | Severe damage.
33 oF 108 2 ek eS 100 Do.
37 5G 180 | Plate girder. ......- 2,000 Do,
The remaining bridges were undamaged. Addi-
tional repairs had to be made and cireuits re-
routed. As explained in the Sanitary and Storm
Sewer Section of this report, water tables that
were normally 8 to 12 feet below ground elevation
rose to within 3 feet of ground elevation (Photo
105). Since manholes were neither water-proofed
nor drained, water seeped through the concrete
walls and saturated the conduits. This caused
more delay in the repair of the remaining sub-
surface system. Cables, being lead-sheathed and
well protected at manhole intersections, were not
water damaged. The telegraphic system under the
Bureau of ‘Telegraphs was totally damaged, and
the system was merged with the Bureau of Tele-
phones. One telegraph line communicating with
Tokyo and Osaka was operating by the middle of
September 1945.
e. The cost of damage, as estimated by the Bu-
reau of Telephone officials on 15 November 1945,
was approximately 10,000,000 yen, or $2,500,000,
at the 4-yen-to-a-dollar rate of exchange.
f. Of the 900 persons employed by the Bureau
of Telephones, there were 350 persons killed, in-
jured, or missing in the Central District Exchange
Building and maintained areas, but none were
killed in the Western District Exchange Building.
g. Information regarding telephones, telephone
equipment, telephone transmission system, and
personnel was acquired from the chief engineer of
the Bureau of Telephones in Hiroshima.
PHOTO 99-XIII. Damage to cable at Bridge PHOTO 100—XIII. Damage to 2,000-pair cable
13A, 4,700 feet from GZ. at Bridge 29, 1,200 feet from GZ.
PHOTO 101-XIII. .Flood damage to Bridge 31 PHOTO 102-XIII. Flood damage to Bridge 37
carrying 100-pair cable, 4,600 feet from GZ. carrying 1,000-pair cable, 3,200 feet from GZ.
223
PHOTO 103-XIII. Damage to telephone conduit cable at Bridge 24, 1,000 feet from GZ.
PHOTO 104—-XIII, Broken cable conduit at Bridge 24,
224
> me
PHOTO 105-XIII. Water-filled, telephone manhole.
Debris-damaged telephone manhole cover 100 feet from GZ.
PHOTO 106 XIII.
225
Secondary cover undamaged.
4. Recommendations and Conclusions
a. At the time of the attack the telephone com-
munications system, although well designed and
maintained, was particularly vulnerable to an air-
detonated atomic bomb because of the method of
transmission. The reasons for the disruption of
80 percent of both the overhead and the subsur-
face transmission systems were as follows:
(1) The overhead system was carried on wood
poles which were vulnerable to blast and fire.
(2) Damage by fire and blast occurred at points
of conversion from subsurface to overhead system.
(3) The bridges used as overcrossings for cables
were damaged by blast and fire.
b. Had the subsurface system been divorced
from overcrossings and had subriver crossings
been used with well-protected exits to overheads,
this part of the entire system would have been
practically free of damage. Thus, the best pro-
tection against this type of attack for telephonic
communications would have been an entire sub-
surface system for the city proper. The subsur-
face system would have minimized the necessity
of repairs. As shown by the existing subsurface
system at Hiroshima, no damage occurred to the
conduits or manholes 4 feet below ground level.
ce. Exchange buildings would have to be numer-
ous, well dispersed, and completely interconnected
as stand-by units to insure service in the event of
damage to the primary equipment.
E. WATER SUPPLY SYSTEM
1. Summary
a. Capacity. The city of Hiroshima main-
tained a water supply system capable of producing
20,000,000 gallons of filtered water per day, or an
average of 50 gallons per day per person. This
system served approximately 90,000 buildings and
dwellings including factories and other plants that
required filtered water. In addition to the pota-
ble water, wells were dug or drilled as supple-
mentary sources for industrial and other uses.
b. Location. The purification plant was ap-
proximately 2 miles in a northerly direction from
the center of the city and the pumping station was
one mile beyond the purification plant. Both were
located on the Ota River (Fig. 16).
ec. Equipment. ‘Table 28 shows the buildings
utilized by the water supply system. Building 1
had four river-intake pumps; Building 3 housed
the standby units consisting of three Diesel-motor
pumps and one generator; Building 4 contained
three booster pumps; two recording meters were
in Building 5; in Building 6 were four reservoir
pumps; and the pumping station had four river-
intake pumps.
d. Filter Beds. There were seven sand filter
beds of 21,120 square feet each, with a 23-foot
filtration rate per day through 3 feet of sand.
e. Reservoir, A reinforced-conerete, earth-cov-
ered reservoir of 4,500,000 gallons capacity was
located 165 feet above the purification plant.
f. Piping. All subsurface piping was standard
250-pounds-per-square-inch, cast-iron. bell-and-
spigot pipe. Equipment connections had screw
ends with flange and bolt connections. Table 29
shows the lengths of cast-iron mains used in Hiro-
shima. Branches for dwellings varied from 14 to
114 inches and, for buildings, 2 to 4 inches. All
mains were buried 4 feet below ground elevation.
g. Valves and Hydrants. ‘There were approxi-
mately 132 cast-iron gate valves rated at 250-
pounds-per-square-inch pressure. Hydrants were
of two types, standard and flush, and were spaced
600 feet apart in congested areas.
There were three booster
pumping stations, including the one at Koi, At
the Koi station there was also a reinforced-concrete
water tower of 234,000 gallons capacity.
i. Overcrossings. Because of the delta system
on which the city of Hiroshima was built, 17 river
crossings were required. Of these, 14 were on
bridges constructed and maintained by the city
highway department and the prefectural govern-
ment; the remaining three were aqueduets, con-
structed and maintained by the water department
of Hiroshima. Table 32 gives the overcrossings
and the sizes of mains carried.
j. Camouflage. Attempts>at camouflage were
made by the Japanese to conceal the purification
plant and the Koi booster station.
hk. Damage to Equipment and Buildings. Dam-
age by blast to the pumping station at 14,000 feet,
and the purification plant at 9,200 feet from GZ
was slight. No fires occurred in these areas. One
mootor in building 4 was burned out because of
falling debris, and the metering equipment iP —
building 5 suffered heavy damage. Building dam-—
age is found in Table28. All buildings in Table 29
are classified similarly to the buildings of the
building damage section. Any conclusions draw!
for the mean areas of effectiveness for building?
and equipment in that section will also apply t@
the buildings and equipment in this section.
h. Booster Pumps.
Yr SSR
“a HIROSHIMA
WATER DISTRIBUTION
Wisc
SYSTEM
LEGEND
© POINTS AT WHICH PRESSURE TESTS
WERE TAKEN
[] POINTS AT WHICH BREAKS OCCURED
PW SUC I
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HIROSHIMA
HIROSHIMA PREFECTURE, HONSHU, JAPAN
oe ee
ph Bas
re | US STRATEGIC BOMBING SURVEY
WATER DISTRIBUTION SYSTEM
| HIROSHIMA, JAPAN
FIGURE 16-XIT
? T, 7? 7 Tdo
731568 O - 47 (Face p. 226)
7 7
= \ ; i. OAS ry 8 nf
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7
as ee : 16 20
PS Se a eee tae ss 12 10
ee ae Loe Sed ES 10 20
Gsce:: Snr pins tae 12 10
/, Bach of the 12 water districts and 4 communi-
ties had from 10 to 12 valves. Gate valves rated
at 250 pounds per square inch were placed at points
where mains could be maintained against breaks or
leaks. Two types of hydrants were used for fire
protection, namely, standard or above-ground type
(Photo 121), of which there were 2,000, and the
flush or subsurface type, of which there were 2,200,
In the congested areas hydrants were spaced at
600-foot intervals,
m. At the time data for this report was being
compiled officials of the water department declared
that full information could not be given as records
had been destroyed. Three booster stations, how-
eyer, as shown on Figure 16, were found. The Koi
booster station did not augment the city water sys-
tem pressure, but maintained pressures for the Koi
area. This station had 30-horsepower, electrically
driven pumps, each having an output of 3,600
gallons per minute. A water tower constructed
of reinforced-concrete had a capacity of 234,000
gallons and acted as storage for the area. Booster
pump stations 1 and 2, housed in wood-frame
buildings of approximately 400 square feet each
(Fig. 16), were of the same capacities as the Koi
station but had no connecting water-tower storage.
All equipment in these stations was of Japanese
design and manufacture. A deep-well pump with
a capacity of 1,500 gallons per minute was installed
to supplement the normal water supply at the
Army Divisional Headquarters. (Pump house
equipment shown in Fig. 37.)
n. Because of the delta formation of Hiroshima
numerous overcrossings were required to com-
plete the water-distribution system (Fig. 16). The
water department of Hiroshima constructed a
crossing originally called the Kandabashi Aque-
duet (Figs. 38 and 29), but it was destroyed by the
flood of 1944, and the 20-inch water main was
transferred to Bridge 10. Similarly, a wood aque-
duct carrying a 14-inch main was destroyed by pre-
Bridge No. Bridge type
| Grid
TABLE 31.—Water distribution overcrossings
5J | Concrete _ - -
$2. -2--
5A (Enkobashi aqueduct) _._. .. 5J Steel truss. -
7A (Sakaebashi aqueduct) -| 41 do
{ie Ae 31 | Concrete. -
5 fe . 5I | Plate girder__.
Lis : 7H do
A Sa : 6G | Concrete. _-
WDA 6G | Steel T_ ~~
22: 5 5H | Plate girder__-
Zien . 3G / Steel arch —_—-
ys ae : 5G | Steel truss_-
30A (Shinobashi aqueduct) —_—_| 5G | do.
Sisoae ae 6G | Conerete__-
S8.-e0 6F | _do-
37. 5G | Plate girder__-
43_... a ---| 4F | Timber____-
ale oS ae Se ee | 4E |
Plate girder______-
eee eo a | Constructed by—
276 | 16 | Highway department.
220 16 Water department.
289 | 22 Do.
307 20 | Highway department.
208 16 Prefectural government.
544 | 12 Do.
259 18 | Highway department.
276 16 | Prefectural government.
164 16 Do.
200 10 Do.
263 16 Do.
350 16 | Water department.
358 16 | Highway department.
410 16 Do.
169 14 | Prefectural government,
: 410 14 Do.
= 240 12-14 | Do,
vious floods and the main was transferred to
Bridge 43. The Enkobashi Aqueduct shown on
Figures 40 and 41, the Sakaebashi and the Shino-
bashi Aqueducts, Figures 42, 43, and 44, are in-
cluded in this report as Bridges 5A, 7A, and 30A
respectively. The overcrossings or aqueducts are
listed as follows in Table 31 which was taken from
the Bridge Damage Section.
o. In 1943 efforts were made to camouflage water
distribution equipment, but the camouflage was
not maintaned. At the purification plant wires
were strung over the settling basins and filter beds
to support netting and garlands, and shrubs and
branches were placed on the reservoir earth cover.
A bamboo and net cover was placed around the
Koi water tower.
3. Analysis of Damage
a. The damage to the pumping station (Photo
107) and purification plant (Photo 108), buildings
and equipment (Photos 109, 110, and 111), 14,000
and 9,200 feet from GZ, respectively, on 6 August
1945 can beconsidered as negligible. All damage
suffered by buildings (Photo 112) and equipment
was by blast. No fires started in this area. Glass
panes in all buildings were broken by the blast, as
well as window frames, doors, and door frames.
Some roof stripping occurred on Buildings 3, 4,
and 6 (Photo 113). Sidewall damage occurred to
Building 8. All building damage is indicated on
Table 28.
6. Splinters of glass from broken window
panes in Building 4 entered the rotor cage of one
motor while it was in operation and the motor
246
shirt-cireuited and burned out as a result. The
metering equipment in Building 5 (Photo 114) suf-
fered heavy damage by blast, but the use of the
valve system was not impaired.
e. Due to a short circuit in the high-tension, 22-
kilovolt lines leading to the Suigenchi electri¢e sub-
station, power was cut off immediately. No dam-
age occurred within the substation. The power
cut-off stopped the pumping stations but, after
examination of the pumping station and purifica-
tion plant revealed no damages, the auxiliary gen-
erator was started. Water was pumped and
filtered from power supplied by the auxiliary gen-
erator from 6 August 1945 until 9 August 1945.
d. The intake (Photo 115), settling basins, filter
beds (Photo 116), and reservoir were undamaged,
No leaks in piping or mains to or from the intakes,
settling basins, filterbeds and the reservoir had
been detected. The water in the reservoir, how-
ever, dropped to a seriously low level because of
leaks in pipes within the city.
e. Building and equipment damage is summa-
rized in Table 28. With the exception of Bridge
29, which will be discussed in another paragraph,
8 leaks in the water-distribution system (Fig. 16)
were found by the water-department officials and
were attributed to the blast effect of the atomic
bomb. After inspection of leaks 1,2, and 3 (Fig.
16) in the 16- and 18-inch mains, it was found that
leak 1 (Photo 117) was in a 4-inch diameter, cast-
iron lateral, directly over a 16-inch main, broken
at the valve body by a falling 19-inch brick wall
from an adjacent building. Leak 3 (Photo 119)
USSBS Report 69
HIROSHIMA
FIG 34-XIII
248
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USSBS Report 69
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IROSHIMA.
FIG 43-XIII
257
PHOTO 107—-XIII[. Pumping station Building, 14,000 feet from GZ. Windows broken by blast.
PHOTO 108—-XIII. Diesel pumping plant, Building 3, 9,000 feet from GZ, showing window frames
damaged by blast.
259
PHOTO 109-XIII. Equipment and electrical panel at pumping station, 14,000 feet from GZ.
PHOTO 110-XIII. Diesel pumping plant, Building 3, showing pumping equipment, 9,000 feet from GZ.
a
PHOTO 111—-XIII. Undamaged pumphouse, Building 6, equipment and switch board panel, 9,000 feet
from GZ.
261
Reservoir
Buildings ™™ Pilter Beds
ae =
PHOTO 112-XIII. General view of purification plant showing buildings, filter beds, and reservoir,
9,000 feet from GZ.
262
PHOTO 113-XIII. Pumphouse, Building 6, showing light roof stripping. Note electrical substation,
9,000 feet from GZ.
PHOTO 114—XIII. Damaged meter and recording equipment in Building 5, 9,000 feet from GZ.
263
PHOTO 115-XIII. Intake system on the Ota River, 14,300 feet from GZ.
PHOTO 116-XIII. Filter beds being processed. Note roof stripping on Building 6, 9,000 feet from GZ.
264
PHOTO 117—-XIII. Leak 1. Four-inch gate valve broken by debris from 19-inch brick wall, 1,100 feet
from GZ.
PHOTO 118—-XIII. Leak 2, 100 feet from GZ. Lead-caulking seal broken in 16-inch main; 4-inch
main undamaged,
265
PHOTO 119-XIII. Leak 3. Street L eracked by building movement, 600 feet from GZ.
PHOTO 120-XIII. Leak 4 caused by falling debris, 3,100 feet from GZ.
266
was a cracked street L connected to a T-inch lat-
eral damaged by the movement of the building
serviced, and leak 2 (Photo 118) was a break in the
lead-caulked seal of an 18-inch main, which could
have been caused by the bomb blast, as the main
was only 100 feet from GZ, but, in view of the
severe action induced in Bridge 22 by the blast, it
is more probable that the bridge movement caused
this leak, otherwise, a series of leaks would have
occurred from the bending action in the mains,
occasioned by blast pressure. There was no crush-
ing of the mains at any place. Leaks 4 (Photo
120) and 5 were also caused by falling debris but
leaks 6, 7, and 8 did not result from the atomic-
bomb attack. It was estimated that 70,000
branches or leads were damaged as a result of blast
or fire damage to dwellings and other buildings.
Because of the great number of open pipes the
pressure of «a normally low-pressure system
dropped to zero.
7. With the exception of one valve, referred to
previously, all valves were undamaged. A few
standard, above-ground hydrants (Photo 121)
were damaged by falling debris but no flush-type
hydrants (Photos 122 and 123 were damaged.
Because of the great number of damaged branches,
however, residents pushed the balls of the flush-
type hydrants from the seats allowing water to
flow for their personal use (Photo 125). After all
leaks had been closed off in mains and laterals and
in all branches or leads that could be reached, the
distribution pressure within the city was brought
up to 15 pounds per square inch, but even then
16,000,000 gallons of water per day were required
to supply the city. As there were no requirements
for water in the city center, that part of the system
was discontinued.
g. The booster pump station at Koi,'8,000 feet
from GZ, was undamaged. Buildings at stations
| (Photo 124) and 2 (Photo 125) however, 6,600
and 5,600 feet, respectively, from GZ, received
structural damage by blast. Apart from the elec-
trical panel damage, no other equipment damage
resulted from the blast. The pumping station at
the Army Divisional Headquarters, 4,600 feet
from GZ, sustained the same amount and type of
damage as booster pump Stations 1 and 2. No
effort had been made to place the booster pump
stations or the Army headquarters pump station
in operation,
A. Bridge 29 (Photo 126), referred to in a pre-
ceding paragraph, was the only bridge acting as
73106847 1s
267
a water crossing (Photo 127) that was totally
damaged directly by blast. This damage did not
deprive the area west of the Ota River of water
since there was another 16-inch crossing within
the same loop. Bridge 43 (Photo 150) was dam-
aged by blast and fire, depriving of water the sec-
tion served by it. Bridge 43 was repaired in
October 1945. There was some movement in
Bridge 22 caused by blast which broke the seal of
leaks (Fig. 16) but not sufficiently to cause inter-
ruption of any service. The angle-chord mem-
bers of Bridges 830A (Photos 128, 129) were twisted
by the blast, but the 16-inch main was undamaged
and no leaks were noted. The floods of 17 Sep-
tember 1945 and 5 October 1945, however, damaged
four bridges (Photos 131, 132, and 133) to such an
extent as to impair their use as water overcross-
ings. The following Table 32 is a summary of
bridge damage as given by the Bridge Damage
Section :
It will be noted that more damage resulted from
the floods than from the atomic-bomb attack.
i. The cost of damage to the water system as of
15 November 1945 was estimated at 3,000,000 yen,
or $750,000 at the rate of exchange of 4 yen to a
dollar.
4. Remarks
a. The city of Hiroshima maintained an ade-
quate, modern water supply system, capable of
furnishing 20,000,000 gallons of water a day. The
system was of rather recent design, and stand-by
units were installed to prevent any interruption in
the service. At the time of the attack the source
of power supply was actually cut off and the stand-
by units were utilized to supply the city. The
equipment at the pumping stations and the purifi-
cation plant was not damaged enough to discon-
tinue service. Thus, it can be seen that stand-by
units are essential, and failure of the main unit
need not halt operations altogether.
6. The 250-pounds-per-square-inch pipe, buried
4 feet below ground elevation, proved to be of ade-
quate strength to withstand an attack of the type
to which Hiroshima was exposed. Damage to the
dwellings and buildings resulted in considerable
leakage from the water branch pipes extended to
them, thereby reducing the water pressure below
normal working pressures. This hampered fire
fighting. Because of the vulnerability of buildings
and dwellings to an atomie-bomb attack, branches
connecting buildings with the mains would be
Tasie 32.—Bridge damage
Bridge No. | ACS Type Litey. sche Damage Cause
boa PSUS | COCKER aioe aati arabe hook oe 16: |, Severe__—-.-=_=_- Flood.
SAS = GrT6h apemel trusses a= bo Sstce -SoemnSsess TO )NOR@S= 202 weds cow
kn ae 9027 0 es (ede 22 SOG) sank Se a
10... 2 ce =i es ODO Gonerete. o5 23 so550-222 5525552. 20 | Moderate-__----- Do.
(Pe. 4700.) Plate 'girder...--.=-=---=----. 16 | None-_---
j hy fats 7, 600 Cel Se ee eee rh sy eee [Ie
jf eee ay 270) (Oandrete.. 225065525225 -5-45- nf (iat dGi se :
yo | -2,,900' | Steel I-beam-----------=-.- F 16 See. |e eee eee
Vl eee = 2603'| Plate: girder2-=. =. ----== 3-2 5-- 1G) (0 ee eer
1 pone — 4360:| Steel-archi=..-.-.=.=----.=-- 1 if) Seen Ci a ae ee
29...- _-)} 1, 190) |. Steel truss: << ..---.-..--=- 16 | Complete--.. -- -- Blast.
30A_- ELT ee OR, Te Ey ie lis ae See Seep 16)|Slight.>...- 2-..- =: Do.
+) (ne 5540) \Contreten. 2o=-see2=+ a wk eae ene 16 | Severe- - -- — Flood.
$8222: __.| 5, 800 Ge Se Sa ea eee eee CG) ee Oe ee eer Do.
Cy ae eS Mey Va a a Ce ee 14) ceca Cs Do.
43. =. 2231) Been in bets —2 2-45 eran aes see eee eS] ewes (: (ee hoes Blast and fire.
y |: ee Cp EOE) iN ag A ae Ci eS oe 12=14- | NonGi2 os ssncn ance
damaged in approximately the same degree as the
structure. This would hold true regardless of the
locality of the attack.
c. Two booster pumping stations were installed
at the locations shown on Figure 16 to overcome
friction losses in the water supply system. Be-
cause these booster stations were improperly
placed and were inadequate in capacity, the sys-
tem pressure within the city varied from 30 to 10
pounds per square inch (Table 31). Any leaks in
the system tended to reduce the pressure to zero
for practical purposes. The structures housing
these units were of flimsy construction and offered
too little protection to the electrical-panel distribu-
tion controls. These vulnerable points made the
system useless at the time it was most needed. To
protect the booster pump stations and insure con-
stant pressure in the mains, heavy, reinforced-con-
crete structures would be required, as well as shock-
resistant electrical distribution panels. A subsur-
face, electrical distribution system, referred to in
Part C of this section would greatly enhance the
chances of continued operations of the booster
stations in case of an atomic-bomb attack.
d. The damage by blast to Bridge 29 interrupted
the service of the 16-inch water main that crossed
the Ota River at that location, but other crossings
in the same area and in the same loop assisted in
supplying water to the area. The twisted members
of Bridge 30A indicated that considerable damage
was received. Had it not been that the strength of
the structure was augmented by the 16-inch water
268
main, it probably would have been further dam-
aged. The structures used as water crossings were
not damaged sufliciently to put the system out of
service, but, in the event of larger bombs, this type
of crossing may not be able to withstand blast
pressures developed. In view of future possibili-
ties, structures such as Bridge 380A, being near to
total damage after exposure to the atomic-bomb
attack of 6 August 1945, must be considered in-
adequate for use as river-crossing aqueduets.
F. SANITARY AND STORM SEWER SYSTEM
1. Summary
a. Waste Water. Because of the delta forma-
tion of Hiroshima, short laterals to the branches
of the Ota River were used to dispose of 80 per-
cent of the residential waste water, while the re-
maining 20 percent was carried through branch
pipes to the sewer mains.
b. Disposal of Excrement: The lack of natural
or artificially produced fertilizer in Japan necessi-
tated the collection of human excrement as a sub-
stitute. To make this fertilizer available to the
farmers on the neighboring islands, the city of
Hiroshima made collections from 70 percent of
the city area. Charges of 50 sen were made to the
residents and 30 sen to the farmer for each 72 of
the 130,000 liters per month collected. Collec-
tions from the remaining 30 percent of the city,
comprising the outskirts, were made by farmers
on the mainland.
PHOTO 121-XIII. Standard-type hydrants. PHOTO 122-XIII. Flush-type hydrant with
Lower view, damaged by debris, 3,600 feet from GZ. operating rod. Damaged in warehouse fire.
PHOTO 123-XIII. Residents using water from flush type hydrant, when ball valve was pushed
from seat, 3,500 feet from GZ,
269
PHOTO 124—XIII. Booster pump station 1. Blast damage to building and equipment, 7,100 feet
from GZ.
PHOTO 125-XIII. Booster pump station 2. Blast damage to building and equipment, 5,900 feet
from GZ.
270
PHOTO 126-XIII. Bridge 29 carrying water main, damaged by blast, 1,200 feet from GZ.
PHOTO 127-XIII. Section of 16-inch water main at Bridge 29, 1,200 feet from GZ.
271
PHOTO 128-XIII. West abutment of Bridge 30A showing minor damage, 1,900 feet from GZ,
PHOTO 129-XIIL. Blast-damaged aqueduct (Bridge 30A) carrying 16-inch water main, 1,900 feet from GZ.
272
PHOTO 130-XIII. Bridge 43 rebuilt, October 1945. Original bridge carrying 14-inch water main,
structurally damaged by blast and fire, 5,200 feet from GZ.
PHOTO 131—XIII. Flood damage to Bridge 3 carrying 16-inch main, 7,100 feet from GZ.
273
“<—Se3
ye Se
PHOTO 132-XIII. Flood damage to Bridge 10 carrying 20-inch main, 7,000 feet from GZ.
PHOTO 133—-XIII. Flood damage to Bridge 31 carrying 16-inch main, 4,500 feet from GZ,
274
ec. Surface Drainage. The sewer mains also
served as storm sewers to carry off a rainfall of
2.36 inches per hour. The recorded maximum was
7.87 inches per hour. Drainage water flowed
through mains and open flumes (Fig. 45). ‘The
water level in the rivers often reached to within
1 foot of the tops of the revetments during flood
stages.
d. Pumping System. Pumping stations (Fig.
45) were used to pump water from the open ditches
to the bay areas when gates could not be opened
to permit gravity flow because of high tides.
Electric motors and manufactured-gas-driven en-
gines were used as power units for the pumps, the
manufactured gas being produced at each station.
Since the gates at each station, which permitted
gravity flow of water when opened or pumping
operations when closed, were manually operated,
a station attendant was required in each case to
operate equipment and gates to keep the rising
waters under control. Buildings housing the
equipment were of the light-frame type, and are
clasified on Table 35,
e. Pipe Lines. Because of the absence of human
excrement, concrete pipe and open flumes were
used extensively. Standard-type manholes were
constructed at important intersections and where
changes in direction occurred. The flow-line
depth in both cases was a maximum of approxi-
mately 10 feet below ground elevation. The
sewer system was composed of 211,230 linear feet
of open flumes of various sizes, 3,170 feet of 48-
inch-diameter clay pipe, 5,970 feet of 48- and 30-
inch-diameter concrete pipe, and 74,980 feet of
concrete-box pipe of varying sizes. Figure 46
shows all types of mains and flumes.
f. Damage. Of the 14 pumping stations, the
equipment in six stations within a 5200-foot ra-
dius of GZ was heavily damaged by blast and sub-
sequent fires. The electric motors in Stations 1 and
5, however, were burned out as a result of debris
falling into them while in operation. ‘These sta-
tions were damaged by blast. ‘The remaining sta-
tions received slight or no damage from the at-
tack. The electric substations supplying power
to the pumping stations were also damaged and
could supply no electricity. ‘Two of the buildings
were structurally damaged by blast and five by fire.
One building received superficial damage by blast
and the remaining buildings were damaged to a
minor degree. Table 35 shows the extent and
nature of the damage. Since the loss of the system
275
was not too greatly felt at the time because of the
fair weather and low water, little or no effort was
made to repair the damage to the stations, despite
the fact that it was not heavy. The seasonal rains
later caused floods which inundated the revetted
areas of Hiroshima and raised the water table
from its usual level to within 3 feet of ground
elevation. This caused serious delay in repairing
other utilities which utilized subsurface systems
and manholes. All buildings in this report, includ-
ing installations and equipment, are classified
similarly to those in Table 35 by the Building
Damage Section, and mean areas of effectiveness
derived by that section for buildings and equip-
ment will apply also for this section, —_
gy. No damage to mains or flumes was wound by
either the city engineer of Hiroshima or by mem-
bers of this team.
h. Costs of Damage. The city engineers esti-
mated the cost of damage to the sanitary and storm
sewer system as of 15 November 1945 to be ap-
proximately 3,000,000 yen, or $750,000 at the ex-
change rate of 4 yen to a dollar.
2. Description of System
a. The city of Hiroshima was built upon the
delta of six rivers which branched from the Ota
River in the northern section of the city. These
rivers simplified the disposal of waste water by
permitting the use of short laterals leading to
them. Since no raw sewage containing human
excreta was discharged into the sewer system, the
problem of disposal was confined to surface drain-
age and residential waste water. The system of
short laterals accommodated 80 percent of the res-
idences of Hiroshima, while flow from the remain-
ing 20 percent was carried through branch pipes
to the mains. Mains, open flumes, and sewage
pumping stations distributed throughout the city
and adjacent areas are shown on Figure 45.
6. Because of the lack of artificially produced or
natural fertilizers, it was the custom throughout
Japan to collect all human excrement for that pur-
pose. In Hiroshima a regular collection system
provided the necessary fertilizers for the agricul-
tural districts. Approximately 70 percent of the
collection was performed on a contract basis, con-
tracts being let to individuals for the period of 1
year. To facilitate water transportation to the
nearby islands which absorbed the total collec-
tions, a storage point was established at a wharf
near Bridge 17, where excrement was allowed to
ferment in tanks for approximately 30 days before
it was sold. Costs were based on a 72-liter meas-
ure and all payments by farmers and residents
were made to the city government. The average
monthly collection was approximately 130,000
liters. Inasmuch as the remaining 30 percent of
the city zoned for collections was on the outskirts,
the farmers in the vicinity of Hiroshima made
their own collections and were paid the established
collection rate of 30 sen per 72 liters.
e. The heaviest rainfalls occurred during the
typhoon season from June through October, the
highest recorded being 7.87 inches per hour on 17
September 1945. ‘The rainfall for which provision
was made in design however, was approximately
2.36 inches per hour. The system was built to
accommodate as an additional load the residential
waste water referred to in Paragraph 2a, all mains
and open flumes serving the dual purpose of sani-
tary and storm sewers. The water impounded by
open flumes and catch basins flowed through mains
and open flumes, as indicated on Figures 45 and 46,
directly into the rivers or the bays from high points
located approximately on the longitudinal center
lines of the islands formed by the rivers. In the
event high river waters resulted from rains or
tides, pumping stations located at strategic points
(Fig. 45) discharged waters into rivers or the bay.
d. The pumping stations were made necessary
by the flood stages of the rivers which frequently
rose to within 1 foot of the tops of the revetments
along the river banks (Photo 147) and occasionally
overflowed some portions of the banks through a
combination of flood and tide. This overflow,
however, was rarely sufficient to cause damage.
e. The sewage pumping stations were divided
into two types: Those operated by electric power,
and those operated by producer fuel. The power
for the electrically operated stations was supplied
to the city of Hiroshima by the Chugoku Electric
Co. (a subsidiary of the Nippon Electric Co.), and
was transformed from 3,300 volts down to operat-
ing voltages. The stations operated by producer
gas generated the fuel at each individual station
by heating coal or wood in air-tight containers
to temperatures required to drive off the gas. The
engines were 2- and 4-eycle, magneto-ignited,
horizontal type, manufactured by the Osaka Co.,
Osaka. The location (Fig. 45), type and output of
each station are listed on Table 33.
f. A total of 930 cubic feet per second was dis-
charged by the above stations operating under
normal conditions. Each station that was pro-
276
Tasie 33.—Pumping stations
Total
Station Grid ike Num- che
No. Type No. herd Bente “eet
second)
— =
1 | Electric motor. __. 7M 30 1
2 | Gas-fuel engine....| 5L 60 2
Sijhaasa do 7L 30 3
4 ar. SJ 60 3
5 | Electrie motor 91 150 3
6 do 41 60 1
Y f | 1 eee 61 60 1
8 | Gas-fuel engine.___| 7H 100 3
9 |) eee Se 4G 30 2
10 | Eleetrie motor___- 4G 60 1
11 (: ee 4G 60 1
12 ota 7D 100 3
13} fo se dg see 7C 100 3
fo.) eee 6202 5G 60 1
vided with a tide gate (Fig. 45) operated whe?
the tide or river was too high to permit direct floW
to open water. The remaining stations were pre"
vided with flood gates and pumps at sewer-mal?
terminals from which the water was pumped whe?
the tide water or flood water had risen too hig”
for normal flow to the river. Other gates, in add
tion to those at the stations, were provided to pr&
vent backflow during high water. All gates, eithet
tide or flood, were manually operated and each!
station had its individual operator to keep the ris®
of waters in the mains and open flumes under co™
trol. With the exception of the pumps at Station®
15, 12, and 13 (deep-well type, manufactured bY
Hitachi Co., Tokyo), all pumps were of the rotary”
centrifugal type, manufactured by the Torishim®
Pump Co., Osaka, and could operate against *
maximum head of approximately 12 feet. The
majority of the electric-motor-driven pumps wer®
direct connected, while the gas-fuel-engine-ope™
ated pumps were belt driven. All stations wer®
housed in light-frame buildings, the majority ©
which had interior plastered walls, but the othet®
had exposed studding. Lighting fixtures were prO
vided for some fuel-gas-operated stations, ‘Tablé
34 gives the classifications of all buildings.
gy. Pipe Lines. The practice of carrying all
waste water and storm water by a single line
greatly simplified the piping system. Because °
the absence of excreta it was unnecessary to pr”
vide special construction and materials in th®
mains and branches to prevent early decay of sew
age lines or the escape of excess sewer gas. The
ac
1
si HIROSHIMA
SANITARY & STORM
. SEWER SYSTEM
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HIROSHIMA, JAPAN
FIGURE 45 XI
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TYPIGAL SECTION
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SEWER DETAILS
HIROSHIMA, JAPAN
FIGURE 46 XII
PHOTO 134-XIII. Aerial photo showing open ditches and dikes at Sewer Pump Station 4, 11,100
feet from GZ. :
278
Tape 34-XI11.—Hiroshima sanitary and storm sewer system— building data
[Areas in thousands of square fect}
Buiding damage (floor area) Equipment damage
Build-| Build-) Dis- | potay
| > : Structural Superficial
Bulld-| Grid Usage Type| fren |rlee| EE Fie “Az — damage |» damage Minor | Per- | 5
Vv V (feet) —| damage | cent Cause
Blast) Fire | Mixed Blast) Fire :
1| 7M | Pump station. _. p | o2| 1| V4 | C | 17,000) 02 Slight......| 25 | Debris,
31 SB do_- p | 1.2] 1] V4 | C | 13,300) 1.2) 1.2 . Sanacd Lp pabindoresev tt ad, Do.
3] TL _.do D 1.2) 1) V4 Cc 3G 00"]}) 2 jo24...)..2.-. : nl eee ed Moderate. -_|.__...
4] py ea ree Dp | 1.2] 1] Va | © | 11,900) 1.2 )---.--} |... Jasn-onfroasocfornasQOp-wee--| S| ‘Do
5| 9 do p | 11/| 1| V4 | C | 13,400) 1.1 aeeat| Ceeee : _.do 23] Do.
6) 41 do D ee) ag Cc 5,400) 3 0.3 ie 75 | Fire,
7| 6 do D 3) 1] V4 c 5,600 | .3 3 75 Do.
8| 7H _.do-. Dd | Ti ove c 7,200) 9 | 0.9 : 10 Debris.
o| 4a | Wasi tas ee D ih v4 | 2, 600 i re } | pe f. : | 75 | Ffre.
10) 4G do Dp: |) .4] 2) Vs Cc 3, 900 re Pos ee oer ty Perrre) peer Stoicinannsene] $40 Do.
i 4G |.....do D | 28 1 va C 3, 700 8 5 | eons) ececes|syoee~ ==== seeees| 45 | Blast.
217 40. p | .8|1| V4 C | 11, 800 8 |. Heshust adcee a laaeebdl peace) SAVERMs 10 | Blast and debris,
| 70 |....- as ee ee D .8| 1] V4 C | 14,900 08 [..+.+-]..----].-.----].--0--|---~- Slight......- 5 Blast,
14'|| «ee eran Seta p| .s| 1} v4 | © | 3200) .3)--.-.. 8 |---- Sohneeseresceoons} 70l| Mikes
| | —
TABLE 35.—Flumes and mains
Clay pipe | Concrete pipe Concrete-box
I . ripe pi a
width (eet) | length Ops | ngthSC? | lengib OP | Ripe tit)
26.33 | 10,900 |.-.---- : 20 :
19. 75 es A ee 3
13. 25 21, 460 |__- Sy er oe
11. 25 800 |_._. oan ae
10. 00 16, 270 |_ 7? a (See
9. 00 9, 000 : <=> :
8. 25 6, 030 ce = a5 4, 670
6. 50 6, 000 = > 5, 830
6. 00 48, 000 a) Lo 7, 940
5.00! 27, 830 : weet 26, 070
4.00 33, 270 3, 170 5, 330 15, 770
3. 33 30, 570 - 14, 130
2. 50 | 1, 640 470
Depths, being variable, are not given and will be found on fig, 45.
! OP—Japanese designation for open flume.
? SC—Japanese designation for clay pipe.
? CP—Japanese designation for reinforeed-conerete pipe. 7 pea
*CC—Japanese designation for reinforced-concrete-box pipe with remov-
able top. ipe
Pipe diameters and wall thicknesses for clay and reinforced-concrete pif
Were given as follows: 5s de teak Clatubder
(1) Clay pipe, bell, and spigot, 2-inch wall, 48-inch diameter, :
(2) Concrete pipe, reinforced, bell, and spigot, 2-inch wall, 48-inch and 30-
inch diameter. m i
Fig. 46, gives open-flume and reinforced-concrete-box pipe dimensions
minimum earth cover for all pipe was 3 feet. The
types of mains and open flumes (Fig. 45) are de-
tailed on Figure 46, ‘The summary of types of
mains and open flumes is shown in Table 35.
h. Access to Pipe. Manholes were installed at
important intersections and at changes in direc-
tion. Ali manholes (Fig. 46) were constructed of
a 2-course brick wall and a concrete foundation.
The flow-line elevation, being dependent on the
279
mean-low-water level of the river, rarely exceeded
10 feet below ground elevation.
7, All lines and mains were traced by the city
engineer's office by field check and memory due to
the destruction of records in the city hall.
3. Analysis of Damage
a. The greatest amount of damage to building
and contents in any pumping station was caused
by fire. The damage to the equipment incurred
by blast was in most instances negligible. With
the exception of Station 11, all stations within a
radius of 5,200 feet of ground zero were destroyed
by fire. Station 11 and the remaining pumping
stations were damaged by blast in a degree propor-
tionate to their distance from GZ. Table 36 cites
the damage to equipment resulting from blast and
subsequent fires.
b. It will be noted that the electric-motor dam-
age of Stations 1 (Photo 135) and 5 is classified as
heavy, the cause being that plaster and debris fell
in the motor rotors while in operation, resulting
in a severe short circuit and burning of the coils.
Stations 12 (Photo 136) and 13, damaged by blast,
suffered small-panel and incidental-equipment
damage, insuflicient to prevent operations. Since
Station 12 was under construction and all equip-
ment was not installed, however, it was not con-
sidered as being in operative condition. The
equipment in the four electrically operated stations
(6, 7, 10, and 14) which were damaged by fire
(Photos 137, 138, and 139) was rendered totally
useless as was that in gas-fuel-operated Station 9
(Photo 140). The operational value of the pumps
in the fire-damaged stations was rendered negli-
Distance |
Station | Grid from GZ Type of damage Engines motors
(feet) |
1) 7M | 16,900 | Blast.......| Heavy damage_-_.
oe 5L 13; 200. | 22.5: do__..__ Slight damage. ____
3 7L 14, 000 | Ai (koe ee Nones ee oats
8J 11, 100 FC: Co fy _.do ~
5 | 91 13, 500)||£== dot... Heavy damage _-
6 | 41 5, 000 | Fire do
és 61 5, 200 do... do
a fee po | 6,900 Blast Slight damage
9| 4G 1, 900 Fire Heavy damage
10) 4G 3, 300 | do do
11| 4G | 3,100 | Blast Slight damage____-
12 | 7D 11, 600 | F< (ee None-
13 | 7C | 14,800 |_...-do oman Sas) oe
14) 5G 2, 800 | Fire __ Heavy damage____
gible becaused of burned packing, fused bearings,
and distorted shafting. As expressed above, the
greatest damage incurred was by the fires as an
indirect’ effect of the atomie-bomb explosion.
With the exception of Station 11 (Photo 141) in
which the electric panel and transformers were
severely damaged by blast, all other stations suf-
fered relatively light blast damage (Photos 142,
143, and 144), except stations 1 (Photo 135) and 5
which were previously discussed. Station 11
(Photo 141), although in a fire area, was an iso-
lated case, being in a sparsely settled district.
c. Operation after the Attack. Gates control-
ling the gravity flow of water to the rivers or bay
areas were undamaged (Photo 145) and, outside of
being somewhat weathered, were considered oper-
ative. Prior to the attack there was little precipi-
tation and only the pumping stations at the far
ends of the deltas were operating to keep drainage
waters in the open flumes at a safe level during
high-tide periods. Subsequent to the attack,
however, none of the pumping stations were oper-
ative because of (1) damages to the equipment in
the pumping stations: (2) lack of competent oper-
ators, repair personnel and facilities; and (3) lack
of electric power to operate electric motors in
pumping stations because of damaged electric
substations, Since the weather was fair at that
time there was no danger of inundation, and equip-
ment repairs could have been made in a few hours
to those stations which had suffered only minor
damage and were outside of a radius of 5,200 feet
from GZ. Only small amounts of material would
have been required for that purpose. Although
the electric substations in the vicinity of these
TABLE 36.—Damage to pumping station and equipment
Pumps | Distribution panels Transformers
i (ops (eee a i None None,
sdoeeas s _do 3 Do.
_do
_do
_do None Do.
Heavy damage _- Total damage Heavy damage.
do : do. Do.
None... -._..-.2]) None
Heavy damage__-
_do Total damage__- Do.
Slight damage.____ Slight damage____- None.
None_--- : __do- Do.
aie 9S een _.do- Do.
‘Total damage- | Heavy damage.
|
Heavy damage_-
pumping stations were in operation prior to 20
August 1945, little or no effort was expended in
making repairs or placing the sewer system in
operation.
d, In addition to direct and indirect bomb dam-
age, exposure to the elements contributed to the
deterioration of otherwise operative equipment,
During the September 1945 heavy rains which
reached an all-time record high of 7.87 inches per
hour, the loss of the system was greatly felt. The
high water in the rivers forming the deltas pre-
vented the escape of surface waters flowing
through the mains, while the gates at the terminals
of the open flumes could be opened only when the
water was low. Thus at high tide the lowlands
behind the revetments were inundated, the water
rising to approximately | foot below the top of the
gates. The run-off in the city center was greatly
hampered. To make the problem more complex,
the water table rose to within approximately 3
feet of ground elevation in the normally dry man-
holes of other utilities (Part D of this section),
thereby greatly handicapping repair efforts. This
condition was made worse by the fact that the
subsurface area was reclaimed river sand and very
porous.
e. Of the 14 frame structures erected to house
the pumping equipment, five were damaged by
fires (Photos 137, 139, and 140) and 9 were dam-
aged by blast (Photos 141, 146, 147, 148, and 149).
Table 35 gives the extent of damage to all pump
station buildings. The wood-frame type structures
constructed for the pumping stations were typical
Japanese construction and could be readily re-
placed if damaged.
280
PHOTO 135-XIII. Equipment for Sewer Pumping Station 1. Motor damaged by debris, 16,900 feet
5 os >
; from GZ.
PHOTO 136—-XIII. Damaged equipment in sewer pumping station which was 11,600 feet from GZ,
PHOTO 137—XIII. Fire Damage to Sewer Pumping Station 7, located 5,200 feet from GZ,
PHOTO 138-NIJII. Pump outlet and gravity flow outlet at Sewer Pumping Station 7, located 5,200 feet
from GZ,
282
PHOTO 139-XIII. Fire damage to Sewer Pumping Station 14, situated 2,800 feet from
PHOTO 140-XIII. Fire damage to Sewer Pumping Station 9, situated 1,900 feet from GZ,
el eS
a
is,
.
PHOTO 141-NIII. Blast damage to Sewer Pumping Station 11, located 3,100 feet from GZ,
a
- 2 i=
: Fie
4 na ns
ae Pat r Ve
,
NV wees See GA a ‘=
PHOTO 142-XIII. Blast damage to Sewer Pumping Station 8, located 6,900 feet from GZ,
284
PHOTO 143-XIII.. Undamaged equipment in Sewer Pumping Station 3, situated 14,000 feet from GZ.
PHOTO 144-XIII. Equipment in Sewer Pumping Station 4, situated 11,100 feet from GZ.
285
PHOTO 145-XIII. Undamaged gate at Sewer Pumping Station 8.
~*~
"A
“ne
PHOTO 146-XIII. Sewer Pumping Station 1 showing minor blast damage.
286
f. There was no evidence of direct bomb damage
to sewer mains (Photo 150), although the nearest
reinforced-concrete-box main, 4.5 feet by 3.3 feet
with a 3-foot earth cover, was only 2,100 feet from
GZ. The city engineer stated that up to 15 Novem-
ber 1945 no breaks had been discovered. The open
flumes (Photo 151) and ditches (Photo 152) were
not damaged but were in some instances partly
filled with mud and rubble. Of all the manholes
observed not one was overflowing, a condition
which would have indicated the presence of broken
or crushed mains,
g. The city engineers at Hiroshima estimated
the total cost of damage to the sanitary and storm
sewer system at approximately 3,000,000 yen as of
15 November 1945, or $750,000 at the exchange
ratio of 4 yen to a dollar.
4. Recommendations and Conclusions
a. Because Hiroshima was built upon a delta of
artificially reclaimed land, separated into islands
by the fast-rising rivers branching from the Ota
River, it was necessary to supplement the natural
run-off by a system of pumping stations to accom-
modate the 2.36-inch-per-hour rainfall, Prior to
the atomic-bomb attack the sanitary and storm
sewer system, of which the pumping stations were
a part, had been adequate, since the system had
always remained operative. Damage to plants
and equipment, principally pumping stations, re-
sulting from the 6 August 1945 attack, reduced the
capacity of the system below the requirements of
the heavy rainfall of 17 September 1945. Any
city such as Hiroshima built on delta land and
maintaining revetments which require the use of
pumping stations for storm water and sewage dis-
posal would be flooded by an atomic-bomb attack
unless proper protection for pumping stations and
Mains were incorporated in its planning and con-
struction.
6. The majority of the pumping stations were
Well designed and maintained, but were not all
adequately electrified. Since, however, this attack
damaged equipment heavily within a radius of
5,200 feet from GZ, improved electrification prob-
ably would not have altered the results in this area
and stand-by units would have served no useful
Purpose, Outside this area, the pumping equip-
ment, in general, withstood the attack.
e. There was no damage to the concrete or clay
Pipes, which indicated that the mains were of sufli-
cient strength. Open flumes were also undam-
aged. Penetrating bombs could undoubtedly
287
damage some portions of subsurface mains. but
this would depend on the penetration depth, the
natural slope, and type of cover. Open flumes,
however, would be extremely difficult to put out
of service.
d. Buildings housing the equipment were flimsy
and none too well constructed. If the buildings
had been constructed of reinforced concrete, much
of the equipment damage resulting from the attack
would not have occurred. The best method of
construction for protection against an attack of
this nature would be the subsurface-vault type
which would have protected against both direct
blast and fire damage. With equipment housed in
such structures the resumption of operations
would be largely dependent upon the availability
of power.
G. DOMESTIC GAS SYSTEM
1. Summary
a. Production. Approximately 75 percent of
the residences in Hiroshima used 1,125,000 cubic
feet of producer gas per day. The heat content
Was maintained at 404 B. t. u. per cubic foot of gas.
b. Equipment. The producer plant was de-
signed by the Japanese and laid out as shown on
Figure 48. Equipment installed was of domestic
and foreign manufacture. The high-pressure sys-
tem was developed by pumping from storage into
the mains. Gas was introduced into the low-pres-
sure system from storage through a station
regulator.
ce. Piping. High-pressure mains were cast-iron,
screwed pipe, and low-pressure mains were cast-
iron, bell and spigot, lead-caulked pipes. Pres-
sures of 6 to 8 pounds per square inch were main-
tained in the high-pressure mains and 6 to 8 inches
of water in the low-pressure mains. All piping
was buried 4 feet below ground elevation.
d. Valves. Valves were sparsely used through-
out the system. Pressure reducers were valved be-
tween high- and low-pressure mains, and the
mains were valved at the producer plants.
e. Bridge Crossings. There were 27 bridge
crossings necessary to carry the mains across the
rivers to the various islands.
f. Pressure Regulators. Pressure regulators
were used to reduce pressure from 6 to 8 pounds
per square inch in the high-pressure mains and to
6 to 8 inches of water in the low-pressure mains.
Gas was introduced into the low-pressure mains
at this point to restore pressure losses caused by
friction and consumer loss.
au!
'
ite
PHOTO 147—XIII. Blast damage to Sewer Pumping Station 3, located 14,000 feet from GZ.
PHOTO 148-XIII. Blast damage to Sewer Pumping Station 12, located 11,600 feet from GZ.
288
PHOTO 149-XIII. Blast damage to Sewer Pumping Station 4, located 11,100 feet from GZ.
PHOTO 150-XIII. Pump outlet and gravity flow outlet at Sewer Pumping Station 6, located 5,000
feet from GZ.
289
PHOTO 151-XIII. Typical masonry open-flume and concrete road crossing, 7,200 feet from GZ.
PHOTO 152-XIII. Rubble-and-debris-filled concrete
drainage ditch, 1,200 feet from GZ.
290
gq. Damage to Equipment and Buildings. ‘Total
equipment damage by blast was slight. The elee-
trical switchboard and recording meters were
heavily damaged, but no other equipment was
damaged. Gas storage was damaged when the
crowns of the holders were torn by the direct effect
of the blast, releasing all the gas which ignited.
The fires that followed burned timber structures
but no additional equipment damage was sus-
tained. The electrical substation supplying this
area was also damaged. The buildings (Fig. 48)
in this section are tabulated as Building 112 by the
Building Damage Section. Any conclusions
drawn for the mean areas of effectiveness by the
Building Damage Section for buildings and
equipment will also apply to this Section.
h. Damage to Piping and Overcrossings. There
Was no apparent damage to the high- or low-pres-
sure mains. Damage occurred to branches leading
to buildings or dwellings where those structures
were damaged. Of the 27 bridges serving as river
crossings, four were damaged by blast and fire,
and eight by floods, The extent and nature of
this damage are found in Table 41. The bridges
in this section are listed by number in the Bridge
Damage Section and any conclusions for mean
areas of effectiveness for bridges drawn by the
Bridge Damage Section will also apply to this
section.
i. Damage to Pressure Regulators. Of the
pressure regulators installed in the system, two
were heavily damaged by blast and fire, the great-
est distance from GZ being 1,700 feet. This does
not establish the limit of effectiveness, since the
low-pressure mains served by the reducers would
be affected in a degree proportionate to the damage
to the reducers,
j. Cost of Damage. The estimated cost of re-
pair and replacement was 300,000 yen, or $75,000
at the exchange rate of 4 yen to a dollar.
2. Description of System
a. The location of the producer plant and its
connecting high- and low-pressure mains which
supplied the city of Hiroshima and its environs
are shown on Figure 47.
6. The producer gas was manufactured from
hard coal, the bulk of it being shipped by rail to
Hiroshima from the Chugoku district where Ube
Was a distribution point. Approximately 75 per-
cent of the residences used gas for cooking and, in
some instances, for heating. There was no indus-
trial use of gas, coal being the main fuel for heat
291
and power, but coke produced as a byproduct was
used both by industrial plants and residences. The
maximum capacity of the gas producer plant was
approximately 1,125,000 cubic feet per 8-hour day,
storage being in 2 holders having capacities of
316,000 cubic feet and 211,000 cubie feet, respee-
tively. The heat content of the gas produced was
maintained at 404 B.t. u. per cubic foot. The dis-
tribution system was divided into high- and low-
pressure mains which carried the gas into and
across the city, and also to the small district of Koi
where the system ended, All pressure reductions
were effected by means of pressure reducers, The
fuel was then transferred through low-pressure
mains to consumers.
ec. The producer plant of the Hiroshima Gas Co.,
as indicated by Figure 45, covered-approximately
2.7 acres, and included all buildings and equip-
ment necessary for the production of domestic
gas. The buildings within the plant area are
covered in the Building Damage Section and are
designated as Building 112 in that section, The
plant was of Japanese design, but had both do-
mestic- and foreign-equipment installations. All
piping within the plant was of cast-iron, screwed
pipe with flange and bolt connections. The gas
holders, as indicated on Figure 49, were of the two-
lift type, capable of withstanding 8 inches of water
pressure. The crown of each holder was con-
structed in pie-shaped segments, without suberown
bracing. Rolled I-beams and framing acted as
guides for rollers on each holder to keep the lifts
in position. Adjustable rollers maintained free
vertical movement of lifts. All joints on the
holders were lapped and riveted. As shown on
Figure 48, both high- and low-pressure systems
started from the producer plant. In the high-
pressure system gas was taken from the holders at
8 inches of water and pumped into the mains at a
pressure of 6 to 8 pounds per square inch. Gas
was introduced into the low-pressure mains from
the holders through a station regulator of the
Elester type (Fig. 50) maintaining a pressure of 6
to S$ inches of water. All gas taken from the
holders was measured by flow meters before being
fed into the mains.
d. The high-pressure mains were cast-iron,
screwed pipe and low-pressure mains were cast-
iron, bell and spigot pipe with lead-caulked joints.
At bridge crossings screwed pipe with flange and
bolt connections was used. Expansion joints were
introduced at these points to allow for expansion
ss
*
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DOMESTIC GAS SYSTEM ; D
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5 LEGEND i phy r Wy, LLU A K
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pilings Selig (6-8 LB/SQ IN) (Gr NW /Z WHo$éot“h :
LOW PRESSURE PIPE (3 LB/SQ IN) : NG
——=— 8°10" 12,14" a6" VAN) J popes N
— 3" 4" 86
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HIROSHIMA, JAPAN
FIGURE 47-XIIL
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STRUCTURAL DAMAGE BY BLAST
WY, SUPERFICIAL DAMAGE BY BLAST
WU
STRUCTURAL DAMAGE BY BLAST AND FIRE
MATERIAL
WAREHOUSE
PIPE SIZES
°
oO
SCALE
PLOT PLAN SHOWING DAMAGE
| BeOS ea eae
BLDG 2A
TAR TANK
TOWER SCRUBBER
" ATER
AiR CONDENSER
/ CONDENSER :
/ BLDG 112 __
COAL YARD
BLDG 12D
|
LABORER'S RESTING ROOM
SECRET
HIROSHIMA GAS GOMPANY
HIROSHIMA, JAPAN
FIGURE 48 - XII
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—————_—_E— Xz —aezs=—Sz_ I), CC SS HHH Het
SEGRET
ALL JOINTS LAP
RIVETED.
679' SMALL HOLDER
83.8' LARGE HOLDER
69.8' SMALL HOLDER
86.!' LARGE HOLDER
71.4' SMALL HOLDER
88.I' LARGE HOLDER
SECRET
GAS HOLDER
HIROSHIMA GAS COMPANY
HIROSHIMA, JAPAN.
FIGURE 49 XII
293
SECRET
GAS PRESSURE CONTROL VALVE
—=—_—_—— TO _ HOLDER
STATION GAS REGULATOR
SECRET
HIROSHIMA GAS COMPANY
HIROSHIMA, JAPAN
FIGURE 5O XIII
294
and contraction with changes in temperature.
Table 37 gives the dimensions for bell and spigot
pipe used by the company. For details see Figure
47.
TABLE 37.—Dimensions of cast-iron, bell-and-spigol pipe
Diam-
olur A B Cc D E F G H 7 t
(inches)
3 3 “4 ™ MM) Me 5 4 4 36
3 3 M4 ™% 4) MMe oS a4 4 oT
34% 34 a us 74| Mo} Mo % %| Tie
4 4 %) 14 34] Mo} MMe a) % “4
4 4 34) 1% %| 136) 1Me a 56} (Mie
4 4 | «1M H| 1%6) 16) 1% 4 %
4%| 4h 36} 154) 1Mel Sie) ie} 14 | Me
4%| 4h %h] 134] Mol '5i6) ie) 14 bi) %
Standard length of each size of cast-iron pipe was 9 feet.
e. Very few valves were employed in either the
high- or low-pressure systems. They were used
only at the pressure reducers and at the producer
plant where the high- and low-pressure systems
were valved as a maintenance measure. The ap-
proximate depth of placement of all pipe was 4
feet below ground elevation; it emerged only at
river crossings or at reducers. Table 38 is a tabu-
lation of all high- and low-pressure pipes as indi-
cated on Figure 47.
TaB Le 38.—High- and low-pressure piping
High-pres-
sure, cast-
iron, screwed
pipe (feet)
Low-pressure,
cast-iron,
bell-spigot
pipe (feet)
Diameter (inches)
Ee See SoS Ee aE Pe (ee 9, 900
14__ 1, 600
12. 23, 100
Ti a ae re aa 6, 600
REET 208 Se, See 3, 300 42, 900
rea Ae ee 13, 200 47, 000
4. : 16, 500 94, 000
ee 33, 000 8, 500
f. Twenty-seven bridges were used as overcross-
ings for domestic gas lines, only bridges owned
and maintained by the city or the prefectural
government being used, with the exception of
Bridge 21A which was maintained by the company.
Table 39 gives the bridges used as overcrossings
for gas mains as shown on Figure 47.
TABLE 39.—Gas main overcrossings
Size of pipe
(inches)
Num- | Bridge}.
Bridge | Grid Type ber of | length
spans | (feet) | High | Low
pres- | pres-
sure sure
5 | (Cen wes ducssereescn 5 Cy Beer 8
7 41 epee pees ee 8 288 4
8 41 Sense ceneocapmaues en 8 518 6
Ww 0100 EES ee al a 7 307 6
2 51 | Plate girder 3 208 |_..-- 8
ISA i ko ae +) bd) Reser 12
18 61 do. iE 309 2
16 61 | Concrete. ...........-.. 7 367 4
17 | 7H | Plate girder__._...-..._- 9 540 6 10
pM mic) [ik tL” ee 16 448 |. 6
19} 6G | Concrete. ______. 7 be 6
SWE iy yl ee es 9 270 6 12
22; 5H | Plate girder.............. 3 Vt |) Rees 8
24 4G-H do. 7 398 |. 8
965) SEL 1) COM OtRs . wwaenase ses M4 560 6
27 | 3G 1 200 |. 8
28} 3G 6 i eee 4
29) 5G 3 ee 12
30) 4G 7 340 6 12
31 | 6G oe). en eS 12 rt Eee 6
33) OF do 12 410 6
35 | 6&G | Plate girdor.............. 8 4 4 -
87. (6G: |... do... 4 169 10
43)) a | tet sc owessancecs a2 16 410 8
44 | 4F | Steel I-beam_.....___. M4 476 | hecies
47 | 4E 10 340 Eee
48 | 4E 4 240 4
295
Data for the above bridges are taken from the Bridge Damage Section,
g. In order to keep the pressures in the low-
pressure mains from being absorbed by friction
and consumer loss, pressure regulators as shown
on Figure 47 were inserted to transfer gas from the
high-pressure mains. Gas at 6 to 8 pounds per
square inch in the high-pressure mains was re-
duced to 8 inches of water for consumer distribu-
tion. This equipment was manufactured by the
Reynolds Gas Regulation Co., of Anderson, Ind.
(Fig. 51).
3. Analysis of Damage
a. At the time of the atomic-bomb attack of 6
August 1945, the domestic gas plant of the Hiro-
shima Gas Co., at a distance of 6,700 feet from GZ,
was producing at its maximum capacity. Initial
damage by blast to operating equipment was
slight (Photo 153). The electrical distribution
panel in the pumping station received heavy dam-
age to the wiring and meters (Photo 154). The
station recording meters were also heavily dam-
aged. Replacements of parts were necessary to
SECRET
el
AIN GOVERNOR
ae, BALANCING
WEIGHT
REYNOLDS GAS REGULATOR CO.
ANDERSON, IND.,USA
GAS SYSTEM REGULATOR
SECRET
US. STRATEGIC BOMBING SURVEY
HIROSHIMA GAS COMPANY
HIROSHIMA, JAPAN
FIGURE 5! XII
296
make this equipment operative. The gas holders,
however, were more severely damaged (Photo
155). The holder crowns were depressed by the
blast (Photo 156) and the downward vertical
movement of the lifts compressed the gas sufli-
ciently to build a pressure that tore the already
weakened riveted joints when the pressure from
the blast front was released, which allowed the gas
to escape. There was an immediate ignition but
no explosion, and all the escaping gas was con-
sumed by fire. Since no gas pressure remained to
hold the two lifts of each holder above the water
elevations of the water receptacles, both lifts of
each holder dropped to the floor elevation of the
water receptacle. Framing members, however,
were undamaged. All operations in the produc-
tion plant stopped immediately. Three hours
subsequent to the blast, fires were started in the
plant area, having been driven to the vicinity by
a south wind. Because of the immediate drop in
water pressure and the lack of electricity to oper-
ate the auxiliary water pumps, no effort could be
made to extinguish the fires. The Sendamachi
electric substation in this area was damaged and
electric power was interrupted. No additional
damage to the equipment by fire was noted.
b. Flash burns affecting the bituminous paint on
the gas holders (Photo 157) were visible on the
sides of holders toward the blast. The structural
members and other obstructions protecting the
paint from the flash are outlined on the holders,
and were easily distinguished.
ce. The damage to the gas holders was insufficient
to halt operations because the producing plant
could operate until facilities could be repaired by
pumping gas directly into the lines without the
benefit of storage, and the small repairs to the
collateral equipment required a minimum of time
and materials, which would permit the plant to
operate at its rated capacity. Company officials
stated that after smal] equipment repairs, opera-
tions would begin early in 1946 by pumping
directly into the lines. This statement did not
seem unreasonable after inspection of the plant.
Figure 48 shows the damage to company buildings
caused by blast and fire.
d, An examination by the company indicated no
breaks in the mains, but since no gas was available
a pressure test was not made to test for leaks in
the lead joints. Approximately 75 percent of the
branches from the mains to dwellings and build-
297
ings were damaged when those structures suffered
damage by blast and fire.
e. As reported by the bridge damage section of
this survey a number of bridges were damaged by
blast, fire (Photos *99, +130, 158, and 159) and
flood (Photos *102 and 160). (Refer to Parts D
and E of Sec. XIII for explanation of * and +.)
Inasmuch as these bridges served as overcrossings
for utilities, gas flow was rendered impossible by
their damage or destruction. Since the floods of
17 September and 5 October 1945 occurred sub-
sequent to the atomic-bomb attack, damage at-
tributed to the floods is mentioned to give a com-
plete history. Table 40 is a tabulation of damage
to bridges serving as overcrossings for the gas dis-
tribution system (Fig. 47) as taken from the bridge
damage section of this report.
f. Because of the loss of whole sections of mains,
both high- and low-pressure type, due to loss of
bridges, districts served by these overcrossings
will continue to be cut off entirely until bypasses
aremade. In the event it were possible to operate
the producing plant such operations would be
greatly reduced because of the number of bridges
damaged or destroyed as a direct or indirect result
of the attack.
g. In tracing the possible bypasses (Fig. 47 and
Table 41) required to operate the system, the 12-
inch crossing at Bridge 13A (Photo #130) could
be eliminated since 8- and 12-inch low-pressure
mains on Bridges 12 and 15 in the immediate
vicinity were available. However, the breaks in
the 6-inch high-pressure main and the 12-inch
low-pressure main at Bridge 21A (Photo 158) con-
stituted a serious problem. The 6-inch high-pres-
sure main over this bridge provided sufficient
pressure to overcome friction losses in the low-
pressure mains and bypasses within that area.
The 6- and 8-inch low-pressure mains over Bridges
19, 22, and 24 might have been suflicient to provide
the necessary gas required for the area west of
the Motoyasu River had not the 12-inch low-pres-
sure main on Bridge 29 (Photo 159) been also dam-
aged. This area was cut off entirely, and unless
temporary structures were erected to provide an
overcrossing for at least the 6-inch high-pressure
main, very little gas would be available to the area
west of the Motoyasu River. The break in the
8-inch low-pressure main over Bridge 43 (Photo
#130) would be negligible because there was no
high-pressure supply. However, since no valves
were installed in this system any attempt to bypass
PHOTO 153-XIII. Damage by blast to coking ovens at the Domestic Gas Plant, 6,700 feet from GZ.
PHOTO 154—-XI11. Damage to electrical switchboard panel in Building 112, 6,700 feet from GZ.
298
~~
PHOTO 155-XIII._ Fire and blast damage to gas holders and buildings, 6,500 feet from GZ.
PHOTO 156-XIII. Crown of holder depressed by blast and section raised by compressed gas, 6,500
feet from GZ.
731568—47 20 299
PHOTO 157—XIII, Flash burns on gas holder 6,500 feet from GZ. Note shadow of office building on holder.
300
Tasie 40.—Damage to overcrossings
Size of pipe (inches) |
Bridge Type raueth ey a — Damage Extent
pressure pressure
Bb. (Generete: 24——. = a 204 6,200 1.2.4. 8 | None___-_.
7 [eceeedOszecaccacssosce J 288 6, 200 |_=.... 4 200%2u5
2 ae 518 5, 400 Eee do
10 =O0.2e S22 esp ee sae 307 1,000" | Ses 6\) Flood2<. =: _.| Moderate,
12 | Plgtte @irdere. ...---->2-2 208 4, 700 >| Nona. 52s. |
ISA} | imibers< <.seau~es=sss55 307 | 4,700 E 12 | Blast and fire - | Complete destruction,
ta) eae 7 eee eee be eee aed 309 | 4,700 : 12) |) Nones.<.- <=.
16 | Conerete ay “BOT 5, 800 : 4 ay: | ee
17 | Plate girder___-_- --| 540 7, 600 6 10 do
16'|Hamberiescvd ase. 448 | 6,000 c 6 do-
1 Le) it 9) tee) Ie = ae eh 259 | 4, 300 aa 6 do asl
PAD hos bots ae = ay oe 270 1, 200 6 12 | Blast and flood____ Do.
22'| Plate girder<. <2... 164 260) eee. 8 | None_-
24 fonda 398 LO00n|c== = 8 | Blast. --- Slight.
26 | "Coneretess -— 223 5s eee 560 D200 T2264 6 | Flood_ Moderate.
27 | Steel arch... -.-- = 200 S400 oes. Ps > Gr
28 | Timber_-=------- He 197 | 4,400 4 | Flood____.._-______| Complete destruction.
2b inbin tr ee 263 1, 200 12) | Blsats oes “a Do.
SO" Conerate-o< =] se. > 2 S2= 340 1, 900 6 12 | Flood. : E | Severe.
SE ll. eROSe bs caves cscca|| S584] 4 HOG 6 See ee Do.
rl Wice aC; Fs eno bel g 410 | 5,300 |_____- 6 =do=.- \ Do.
35 | Plate girder_-—___ 264 3, 200 4 ae wdOsnc ances | Complete destruction.
Biieeee do s-eeee : 169 | 3, 200 10 |" eacdo=- : | Severe.
43) | \imb@r oa aa as aeons 410 5, 200 es 8 | Blast and fire ___- Complete destruction.
44 | Steel I-beam__-_._- 476 | 5,300 4 None: ==<2----8<2;
Pf) ee ne ee ee 340 | 7,500 rh ee coat eas
48 | Plate girder...__...._-- 240 | 7,100 |. 4 _do. ;
would necessitate the installation of valves to ac-
commodate each bypass. The floods of 17 Sep-
tember and 5 October 1945 totally or heavily
damaged other bridges (Photos *102 and 160) as
Was previously shown and presented additional
difficulties since they also served as utility over-
crossings.
h. Pressure regulators in the distribution sys-
tem located on Figure 47 weye damaged (Table 41)
as follows:
TaBLe 41.—Regulalor damage
Pres- Distance
sure reg-| from GZ Type Damage extent
ulator (feet)
1 700 | Blast and fire...__.--_-- Heavy
201 Sa 7OOKiese2 U0: neck eae Do.
3 B2ORGY NONOdaG sa sean ea es eee
4 | 10, 700 |__-_: ice ee Ce ee A
The greatest damage to Regulators 1 (Photo 163)
and 2 (Photo 164) was distortion to the balancing
mechanism and freezing of the valves by fire.
301
Only a small amount of damage was incurred by
blast and that was by flying debris. Both regula-
tors, however, were rendered useless. No damage
was Visible to Regulators 3 and 4 and no breaks or
damages to piping was noted at these points of
exit.
i. The estimated cost of repair and replacements
of equipment and material by the company as of
15 November 1945 was 300,000 yen or $75,000 at
the rate of 4 yen to a dollar.
4. Recommendations and Conclusions
a. The gas producing plant, although 6,700 feet
from GZ, received sufficient equipment damage to
halt production of domestic gas. The weak point
in the system was the electrical distribution panel.
The metering system and gas holders, not being
essential to production, could be bypassed until
repairs were effected. It can be concluded that a
well protected electrical distribution panel would
eliminate this weak point and, upon resumption of
electrical power supply, the gas plant, with by-
passes and few repairs would be in operation.
PHOTO 159-XIII. Broken gas main at Bridge 29.
Over-crossing structurally damaged by blast, 1,200
feet from GZ.
PHOTO i60-XIII. Bridge 30, carrying 6-inch, high-pressure and 12-inch, low-pressure gas mains, damaged
by flood. Aqueduct 30A in background, 1,900 feet from GZ.
303
PHOTO 158-XIII. Damaged gas-main supports at Bridge 21A, 1,200 feet from GZ.
PHOTO 161-XIII. Bridge 27 carrying 8-inch, low-pressure gas main, undamaged, 4,400 feet from GZ.
PHOTO 162-XIII. Undamaged Bridge 47 carrying 4-inch, high-pressure gas main, 7,500 feet from GZ.
304
PHOTO 163-XIII. Pressure Regulator 1 damaged by debris and fire, 800 feet from GZ.
PHOTO 164—-XIII, Pressure Regulator 2 damaged by debris and fire, 1,800 feet from GZ.
4. There was no damage to the cast-iron, screwed
or bell and spigot pipe buried at 4 feet below
ground elevation. The damage, however, to the
dwellings and buildings to which the pipes were
extended, damaged the gas branches. Because of
the vulnerability of the dwellings and buildings,
this damage would occur regardless of locality.
But an efficient cut-off system for each branch
from the main would aid in maintaining main
pressures and reduce the loss of gas until branches
above ground were repaired.
c. Because of the islands on which Hiroshima
was built, numerous bridges were necessary to
keep communications open. The domestic gas
mains were dependent on these bridges as over-
crossings, and the failure of any bridge acting as
an overcrossing might also mean the failure of
part of the system. If a high-pressure main were
being carried, the whole system beyond that point
would be out of service. This would be true where
the attack damaged bridges carrying a 12-inch
low-pressure main and a 6-inch high-pressure
main. The area beyond those points could not be
served by low-pressure pipes because of pressure
losses. But subriver crossings would eliminate
these hazards and should be utilized as much as
possible to minimize the damage from similar
attacks.
d, Pressure regulators converted high pressure
to low pressure for consumer distribution. The
damage received by regulator 2 at 1,700 feet from
GZ did not confine the limit of effective damage
solely to its area for these reasons: (1) Damage
was such that no gas could flow and the area was
cut off in proportion to the distance to the next
regulator, depending on a loop system being in
the area, or (2) the pressure in the high- and low-
pressure systems was equalized, creating a danger-
ous situation for consumers. In order to protect
the regulators against damage from similar at-
tacks a good solution would be to install them in
reinforced-concrete manholes constructed below
ground elevation.
306
SECTION XIV
DAMAGE TO STACKS
Page
RUNNERS ees a ee on oe Bln Sais pe Bee ee ne en re es 2 ae eS 308
Gay-outs and: OOnAMUCHONS. ose 8 oS eae oe en oe Se ee Se ee ee ee ee eee 308
Analysis of damage — 309
Resommandations ard conclisions.. : lite l.8 . 9s Sle Ss fe a ee eerie ne eee ee eee aes 309
Photos 1—22, inclusive.
Figure 1.
Table 1.
307
1. Summary
The part of Hiroshima which was affected by
the blast of the atomic bomb contained numerous
stacks of reinforced concrete, brick, and steel
(Photos 1 to 4), averaging less than 70 feet in
height and designed to serve small industries and
public buildings. Very few stacks in excess of 100
feet in height had been built in this area. In
obtaining data, a method of sampling was em-
ployed which gave a good cross-section of both
damaged and undamaged stacks of the three most
prevalent types. The survey revealed the stacks
to be generally well designed, but frequently
poorly constructed. Although in many instances,
particularly in the case of undamaged stacks, it
was impossible to get complete details and dimen-
sions, sufficient data were obtained to lead to rea-
sonable conclusions. It was estimated that within
a concentric area of an 8,700-foot radius from GZ
(beyond which no further damage to stacks was
encountered) 15 percent of the concrete, 50 percent
of the brick, and 70 percent of the steel stacks were
damaged sufficiently to render them unusable
without almost complete rebuilding. In all cases
the cause of damage was believed to be blast. De-
tailed analysis of the data disclosed mean effective
areas against stacks constructed of concrete, brick,
and steel to be 0.3, 2.7,.and 4.1 square miles, respec-
tively (Fig. 1).
2. Lay-out and Construction
One of the oddities in the appearance of Hiro-
shima was the existence of numerous apparently
undamaged stacks rising out of the rubble of the
flattened buildings they had formerly served.
Further elaboration of this picture is given in the
succeeding subparagraphs,
a. Types of Stacks. The portion of Hiroshima
which was most heavily damaged by the atomic
bomb contained numerous stacks, both damaged
and undamaged, averaging less than 70 feet in
height. Large stacks serving heavy industry were
few in number in this area; only six of those
studied were 100 feet high or over, the highest. be-
ing 120 feet. Concrete stacks were by far the most
numerous; brick types averaged less than a third
of the total: and steel units were little in evidence.
Several other types, such as vitrified-tile and asbes-
tos-pipe, were encountered but were not considered
worthy of study.
b. Survey Method. The survey was based not
upon data from all stacks in the area, but upon a
308
sampling of the area. The method employed was
to compile data on stacks selected for study on
the basis of location, type, and degree of damage,
in order that accumulated data might represent a
fair sampling of all the stacks. Proceeding clock-
wise around GZ, 16 stacks were selected from the
northeast quadrant of the city, 23 from the south-
east, 14 from the southwest, and 13 from the north-
west. The stacks were distributed over the
quadrants and extended 8,700 feet from GZ,
beyond which no further damage was encountered,
c. Functions. Most of the stacks in the blast
area had served small industry and publie build-
ings. Large stacks serving heavy industry, which
was not very prevalent in Hiroshima, were con-
fined largely to the southern extremities of the
several islands comprising the city and hence were
beyond the effects of the atomic blast. Typical
industries served by the stacks studied in this sur-
vey included relatively small establishments for
the manufacture of needles, cameras, paint,
matches, precision instruments, and similar items.
d. Design ond Construction, Concrete stacks
appeared to be well designed. Walls were suf-
ficiently strong to withstand heavy wind-loads, as
well as the earth tremors so prevalent in Japan,
without any appearance of clumsiness or excessive
thickness. Spacing and size of reinforcing steel,
wherever exposed to view, compared favorably
with United States standards. The quality of
workmanship, however, was generally mediocre.
Reinforcing steel was not carefully placed and
concrete thickness was permitted to vary consid-
erably. Clumsy wood forms were used in sections
averaging 4 or 5 feet in height, rather than the
more practical steel slip forms. Some stacks were
coated with a half inch of cement plaster in an
effort to cover their rough appearance. Many of
the concrete stacks were brick lined, usually one
course, to a height of 10 or 15 feet. Brick stacks,
especially the larger, octagonal-shaped ones, were
usually both well designed and well constructed.
Materials and workmanship were good. The
smaller, square-shaped brick stacks, such as might
be used on a public bath house, were built too
lightly and frequently had to be braced with angle
iron or steel straps and bands. Steel stacks were
in a small minority. They followed no apparent
standard in design; some were lap welded; others
had riveted joints. Their chief weakness lay in the
method of anchoring them to the brick base; anchor
bolts, for example, extended through only four
courses of brick in some instances, and were inef-
fective in preventing overturning.
3. Analysis of Damage
a. Tabular Data. Table 1 shows the physical
characteristics of each stack studied and the extent
of damage, if any.
b. Extent and Cause of Damage. It is esti-
mated that within a radius of 8,700 feet from GZ
15 percent of the concrete, 50 percent of the brick,
and 70 percent of the steel stacks were damaged
sufficiently to make them unusable without almost
complete rebuilding (Photos 5 to 22). The re-
mainder suffered either no damage or only minor
damage, such as loosening of the cement-plaster
finish coating or loss of all or a part of the steel
ladders. Minor damage which would permit re-
use of the stack without repair was not considered
in this report as damage. The cause of damage
was believed to be blast in all instances, since there
was no evidence of spalled concrete, vitrified brick,
or oxidized steel which would have pointed to fire
as the cause of damage.
c. Evaluation of Field Data. A total of 66
stacks was studied. It was possible to get good
data on the 20 damaged stacks. On a few of the
undamaged stacks it was possible to get data on
thickness, size, and spacing of reinforcing steel,
and other characteristics where the entrance cf
the breeching was above ground and accessible, but
it was impossible to get complete data as the flue
entrance was usually underground and covered
with tons of rubble and debris. All concrete stacks,
309
even though no reinforcing steel was visible, were
believed to be reinforced. Although some data
were impossible to obtain without destroying the
stacks, sufficient information was secured to lead
to reasonable conclusions.
4. Recommendations and Conclusions
Analysis of the data revealed reinforced-con-
crete stacks to be the most effective in withstand-
ing the blast of the atomic bomb. Brick proved
highly vulnerable, and steel appeared most subject
todamage. The mean areas of effectiveness of the
bomb against stacks of reinforced concrete, brick
and steel were 0.5, 2.7, and 4.1 square miles, respec-
tively. The mean effective radii were 1,625, 4,900,
annd 6,050 feet. These conclusions, it must be
remembered, are based upon the effects on stacks
which averaged less than 70 feet in height. From
the standpoint of economy, speed, and ease of con-
struction it appeared that practically all of the
stacks studied and reported on herein should have
been constructed of steel pipe securely anchored to
a reinforced-concrete base. Such a stack, even
though blown down, could be quickly repaired on
the ground and re-erected in one piece with the aid
of a crane. Higher stacks, such as those of 100
feet or more, should be built of reinforced concrete
or brick. The preponderance of concrete and
brick as materials for stacks averaging no higher
than those studied in Hiroshima was probably a
reflection of the relative scarcity of steel and
abundance of cheap labor in Japan.
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‘oa en | Sees <2 | SE aos | 00" | IF — | oF
“od rr A rn wosB}9Q |*---====-===- wud | 008'* | IF | FF
oa s | a 2 Sane (sachigesaac x op 000’ | HF | &F
0d Di O08) eae Lear ee eee op-----| oo8'e | He | a
“od SOO Wa cope Stal pge nee op----| oo9'e | He | 1+
“od Go Hig |= Cee ee op ---|oor'z | He | OF
“OUON ee i a lea OHO | nes menuoy |oss't | He | 68
“od ib | 09 eae ae ae op---| oo‘ | D9 | se
"a 08 18 JO | “wos oTFUB[wyUOZL0y puE [wo
pasuoys {097 OL AoE syousy | -H4a yam pooesq Jey daddga | VN | VN | VN | WN [oT 1 Do: De Le
(gegen |(eauous)| (Sou) |(eoqour)| (secur) | eouous)} (4201) | (90) (999)
sdeutip jo wrdpoecct saanyuay [Byods —_———_ ~~ + -—|——-
Suyosojuyos Suyosoyuyos
Tuozuoy =| peurpnyrduo’y SSOUNOY TL, aus
TYPICAL UNDAMAGED STACKS
PHOTO 1-XIV. Stack 9. Typical steel stack PHOTO 2-XIV. Stack10. Typical reinforced-
with brick base. concrete stack.
312
SECRET
GRAPHIC SUMMARY OF DAMAGE TO STACKS
SHOWING LOCATION OF CONCRETE, BRICK AND STEEL STACKS WITH RESPECT TO DISTANCE FROM GROUND ZERO (GZ)
: 4
N e oe
a b i i 3 = li i |. = It
z re ° lo ae = 4 | ° | ° | °
3 8 S ls 8 8 i | 8 l FE
$s re) 1 2 - | 8 | 8 | e | ® | -
2 3 48 sa 2 ee 5 | a SI 41 16 42° qyi7 2122 6| 3 Ao 57 568 24 25/26 27 64 | 66 35 33
CONGRETE Y pl pit Ole oii! stig teé sereers pt btotYi ta bb <666+106 areas ~
@ “4, 4 ‘D LZ, op, LL "FAtr Ate, Pp (h (1) =
1 39 4 54 45 | 59 | | POOR CONCRETE | | l
MEAN RAD. EFFECTIVENESS | | | | | | |
CONCRETE ——> | |
, | | | | | |
4 50 | — oe 38 44] {30 29 7-23 6 65 36 37 34
BRICK i> 40 oP iY, ) ad tte ar > ‘ae anvane 7 ah (T\ 2 (TY
, " S “4% i + WY WV @ uP, wae ae
18 20 l l |
| | | |
| MEAN RAD, EFFECTIVENESS | | | | |
| | BRICK ———= | | | l
53 | 62 58 |9 63 28
STEEL , r. aud > 2
J} 4 IP Ate,
| | |
| | MEAN RAD. EFFECTIVENESS | | | | |
STEEL ———= l |
| ! |
AREA= | SQUARE MILE 2 SQ Mi ae ean 3 SQ MI a 4 SQ Mi ee ey Ml = MI oe sQ Mi ot eo som ol 9 sa ia
CONCLUSIONS
LEGEND
MEAN AREA OF MEAN RADIUS OF
© — UNDAMAGED, OR USEABLE WITH MINOR REPAIR Eo Pic bt tect ll
CONCRETE —-—— 03 SQ MI —— _ 1625 FT SECRET
— COMPLETLY DESTROYED, OR REQUIRING R ee ee see Sones
@--c ° 6 REBUILDING BRICK 2.7 sQ MI 4900 FT U.S. STRATEGIC BOMBING SURVEY
STEEL—-——— 4180 M1 — — 6080FT DAMAGE TO STACKS
HIROSHIMA, JAPAN
FIGURE |- XIV
731568 O - 47 (Face p. 312)
GRAPHIC SUMMARY OF DAMAGE TO STACKS
ADGROMIWOHE STEEL STACKS WITH RESPECT TO DISTANCE FROM GROUMS
A
a
“
Septo ia a al Ke "oe iF SHOMO:
e Lia
—ew se ee a OS Se CED RS
ek
S23n3VITOSIIZ OAR KAIM
—— 3TIAONOD
29 yome?
a” Trewern | te Pet tt te ee
. ; : ;
| : _ ~~ WEAN AAD. EFFLOTIvEeNEss |
,. Oe we | - arc ———- ) : 1
| fh bal) )
aud09 FUSIONS
ne “ras amen OF ~~ Mea mais oF 5 et
~ aiaage tnt sega" EFFEOTIVENESs ie Se
‘ —— ieee er
ensastuesn omniygay MO aaveRtasa viT3 <5 ee
STE _- = 2 = ~~ 6080 fT
TYPICAL UNDAMAGED STACKS
PHOTO 3-XIV. Stack 5. Typical square brick PHOTO 4-XIV. Stack 36. Typical octagonal,
stack. brick stack.
313
DAMAGED REINFORCED CONCRETE STACK
PHOTO 5-XIV. Stack 3. Reinforeed concrete, 1,100 feet from GZ,
DAMAGED REINFORCED CONCRETE STACK
PHOTO 6-XIV. Stack 14. Reinforced conerete, 2,400 feet from GZ, with 1s-ineh heating pipes protruding
from base.
731568—47 21 315
DAMAGED REINFORCED-CONCRETE STACK
PHOTO 7-XIV. Stack 48. Fractured, reinforeed-concrete PHOTO 8-XIV. Stack 48. General
stack, 1,300 feet from GZ. view of stack shown on Photo 7.
316
DAMAGED REINFORCED-CONCRETE STACKS
PHOTO 9-XIV. Stack 27. Reinforced
concrete 6,800 feet from GZ.
PHOTO 10-XIV. Stack 54. Reinforced concrete, PHOTO 11-XIV. Stack 12. Reinforced
4,000 feet from GZ. Sheared off at 55 feet. concrete, 1,900 feet from GZ. Fractured at 16 feet
317
DAMAGED BRICK STACK
PHOTO 12-XIV. Stack 38, Square, brick, 4,500 feet from GZ. Sheared off at 30 feet. Note angle-iron bracing.
318
DAMAGED BRICK STACKS
PHOTO 13-XIV. Stack 4. Hexagonal brick, PHOTO 14-XIV. Stacks 19 and 20. Square,
1,700 feet from GZ. Sheared off at 12 feet. brick, 4,200 feet from GZ. Sheared off at 35 feet.
i]
PHOTO 5-XIV. Stack 30. Square, brick, PHOTO 16-XIV. Stack 32. Square, brick,
5,000 feet from GZ. Sheared off at 35 feet. 1,000 feet from GZ. Sheared off at 20 feet.
319
DAMAGED BRICK STACKS
PHOTO 17—XIV. Stack 37. Square, brick, PHOTO 18-XIV. Stack 50. Square, brick,
8,100 feet from GZ. Sheared off at 20 feet. 2,400 feet from GZ. Sheared off at 30 feet.
PHOTO 19-XIV. Stack 25. Square, brick, PHOTO 20-XIV. Stack 60. Square, brick,
3,800 feet from GZ. Sheared off at 30 feet. 6,300 feet from GZ. Sheared off at 30 feet.
320
DAMAGED STEEL STACKS
PHOTO 21-XIV. Stack 62. Steel with brick base, 5,200 feet from GZ.
Failed at anchorage to base.
PHOTO 22-XIV.. Stack 28. Steel with brick base, 6,900 feet from GZ.
Failed at anchorage to base.
321
SECTION XV
PHOTO INTERPRETATION
OE ISCNOR NIC ce Se oe SN PU LS eee fare LAM es 3S oe ek et) eee a ee oa
PURNIUALY see Soe a ate ole eee Peewee ise ees aa dO ee Ree ka eee eee oe ae See ae
Rip noreOnmmnOn: :6 92 7-2. Se teres ae en een pe & Line hae Weighs aS ss pa ae Se Pa ae
Part 1. Influence of the atomic bomb on photo interpretation_____ Be Sef Pa, 5 ee aS ee ee
2. Characteristics of atomic-bomb damage as seen on aerial photographs_________.__-.-_-__-_____-
3. Evaluation of photographic interpretation physical damage report .._......_..---_.-_-----___- =
4. Evaluation of photographic interpretation industrial report _____........__-.-____------______-
DEVE ON Of SOItOry TAraOG HOMLUSISE eel te See Sw ache eth aee seeoP ont ee eam etna eae en
6. Value of photographic intelligence to ground surveys-_-_--_---------------------------------__--
Photos 1-7, inclusive.
Tables 1—12, inclusive.
Figure 1.
322
1. Object of Study
The objective of this section of the Hiroshima
Physical Damage Report is (1) to recommend
technical changes in photographie interpretation
techniques necessitated by the use of the atomic
bomb; (2) to study the characteristics of atomic-
bomb damage which will be apparent on aerial
photographs; (3) to evaluate the accuracy of in-
telligence reports based on photographic coverage
of the Hiroshima area; and (4) to comment on
the value of photographic interpretation to a
ground survey.
2. Summary
a. New techniques or variations of existing ones
which will take into consideration the integrated
industrial, military, commercial: and domestic
activities and the diverse structural types which
comprise an area under analysis as an atomic-
bomb target must be developed for both preattack
and postattack intelligence reports.
6. Although there are some distinctive char-
acteristics of damage which result from an atomic-
bomb attack, they are similar to those which have
been associated with previous weapons, and the
two basic causes of damage, blast and fire, can be
identified by current photographic interpretation
techniques.
e. The Physical Damage Report on Hiroshima
prepared by the Joint Target Group was generally
correct in description of the damage, but was inac-
curate in respect to certain details: Ground zero of
the blast was mislocated by approximately 1,130
feet; the reported area of total damage was sub-
stantially correct, the mean area of effectiveness
(MAE) of the bomb was slightly overestimated ;
and the reported damage to concrete buildings did
hot correspond to the findings of the ground
survey.
d. The photographic intelligence study of the
Japan Steel Works, Ltd., reported correct, or
closely allied, occupancy to buildings comprising
20 percent of the total plant area and gave a rea-
sonably accurate description of the vulnerability of
the plant to blast damage, but underestimated the
vulnerability of the target to fire.
e. General information concerning Hiroshima
as a military target was relatively accurate. Few
reports had been prepared on the area and the
amount of intelligence information was limited,
since the city was neither one of the primary urban
targets, nor was it highly industralized.
323
f. Photographic intelligence has proved a defi-
nite aid to ground survey groups in establishing
the validity of interrogations, checking the status
of the target on specific dates prior to the arrival
of the field survey, and as guide and index for the
area,
3. General Information
It is the opinion of the members of the team that
the factual information presented herein is ac-
curate and in suflicient detail to warrant the recom-
mendations and conclusions which are reached.
a. Part 3 of this section is an evaluation of the
aceuracy of a physical damage analysis prepared
by the Physical Vulnerability Section, Joint
Target Group, dated 1 September 1945, as Special
Project PV-P82. A complete copy of this report
is filed with G-2, U. S. Strategic Bombing Survey.
b. Part 4 is an evaluation of the accuracy of an
industrial photographie interpretation report on
the Japan Steel Works, Hiroshima Branch, pre-
pared by AC/AS Intelligence, Photographie Divi-
sion, as Buildings Construction Analysis (BCA)
No. 60, dated 9 June 1945. A copy of this report
is filed with G-2, U.S. Strategic Bombing Survey.
c. Part 5 is an attempt to evalute the preattack
general target information concerning the city of
Hiroshima. As a basis for study CINCPAC-
CINCPOA Bulletin No. 845 of 15 January 1945,
entitled “Air Information Summary,” and Inter-
pron Two Report No. 576 of 10 May 1945 were
used. Since Hiroshima was not indicated as a
target of primary importance, no detailed pre-
attack urban analysis was done on the city.
PART 1. INFLUENCE OF THE ATOMIC
BOMB ON PHOTO INTERPRETATION
1. By the close of World War II, photographic
interpretation had developed into one of the most
important sources of intelligence concerning the
enemy, his resources, plans, and action. In con-
nection with the strategic bombing program, it was
especially important in locating and identifying
important targets, in determining the vulnerabil-
ity of such targets to weapons available, and later
in assessing the physical damage to the targets.
The extensive use of photographic intelligence re-
sulted in the development of certain techniques for
obtaining necessary target information; with the
advent of each new weapon or tactic a new tech-
nique was required. For instance, when area
incendiary attacks were begun, photographic in-
terpreters were called upon to determine com-
bustibility and built-upness of areas, to locate
firebreaks and fire walls, and the like, factors
which would affect the number and type of distri-
bution of bombs to be dropped. Many of these
data had not been required for high-explosive,
“pin-point” bombing used prior to this time. The
use of the atomic bomb requires additional changes
in photographic interpretation techniques.
2. Basically an atomic-bomb attack is an attack
by a single, highly effective bomb which will cause
damage to an extensive built-up area comprising,
singly or in combination, urban, industrial, and
military concentrations. The concept of an attack
which affects the integrated activities of a target
area is prerequisite to the analysis of the changes
in photographic intelligence techniques suggested.
a. Preattack Analysis. (1) The concept of a
target must be revised to comprise an area of in-
tegrated activities rather than an individual build-
ing, individual plant, or single military instal-
lation.
(2) A suitable method must be developed for
evaluating the economic vulnerability of a target
area, which will take into consideration the in-
tegrated industry, transportation, services, utili-
ties, and housing which would be affected by
attack,
(3) A suitable method must be developed for
evaluating the physical vulnerability of a target
area, one which takes into consideration the diverse
structural types and the mean area of effectiveness
of an atomic bomb to each, assuming the aiming
point is known.
(4) A suitable method must be developed for the
relative evaluation of different possible aiming
points with respect to both economic and physical
vulnerability of the target.
b. Damage Assessment. (1) The over-all pat-
tern and extent of damage to an urban concentra-
tion resulting from an atomic-bomb attack differs .
somewhat from those resulting from an attack by
high-explosive or incendiary weapons, but the
characteristics of damage to an individual struc-
ture remain unchanged as far as photographic
evidence is concerned. Therefore, no basic change
in interpretation techniques is required, but more
rapid methods of analyzing the economic and
physical damage to an area will be necessary.
PART 2. CHARACTERISTICS OF ATOMIC-
BOMB DAMAGE AS SEEN ON AERIAL
PHOTOGRAPHS
1. A study of the damage to Hiroshima gives
evidence of certain characteristics which can be
324
associated with the atomic bomb.