)

/

JULY 1945

JAPANESE

II KNOW. YOUR ENEMY!"

CinCPac-CinCPOA

~~~)4~?3 .lM-J. ?~

UNCLASSIFieD _"'!llI 1M! , ,

JAPANESE BRIDGE BUILDING AND RIVER CROSSING

I INTRODUCTION

With thePa~if'ic War rapidly developing int.o operations involving large land , masses and all types of .terrain, the Japanese can be expected to employ their army

engineering lDlits extensively inbridgeconstruct;Lon and river crossing methods essential for speedy, efficient transport.

. So far the Japanese have had few opportunities to exploit their bridge building capabilities, in the S'NPA and POA. Captured documents and reports from observers in' Burma and the Philippines hOwever indfcate their training and systems used in crossing rivera and streams ~ve proved sound and workable.

Considerable criticism has been made of Japanese engineering/methods, because their bridge const.ruction does not come up to technical specifications Of, American standards. This criticism is based upon fallacious canparisons. The size and amount of equipment moved by the Allies is much ~eater than that' moved by the Jape.' Japanese engineers 'construction need not beaastrong as ours. The true measure or theengineers t , effectiveness .is whether or not they fulfill their mission. By this standard the Jape. have perfonned exceedingly well in past operations.

In Burmaaecording to U.S. observers, the Japanese ade'quatel)" demonstrated their ability, using conventional as well as many iilge1rl.OU8 methods for water crossings. Muoh of the enemy's ,success in that campaign has been credit ed to his efficient construction work.,

Ylhentactical conditions permit,' the Japs follow a pattern similar to our own in moving men and materials' across rivers and swaJnps. They use pontor;l bridges, girder and trestle bridges, boats and barges. But in improvisation they have shown outstanding ability, g!nerally developing the expedient from local materials obtained near t~e site or construction. '

It is evident that the Japsintend to resort frequently to expediency since their engineers in forward areas have been toundto be scantily equipped, apparently, depending largely upOn,hand tools, local materials and frequent useo! coolies aId natives for labor.

Japanese bridge construction ~mbrac~8 two methOds: Constroctionby successive bays, and "construction by parts. These methods are sub-divided intoconstroction on land and tliat done on water. However, the keynote of orders to engineers in recent months, taken traa a document captured on Guam, has been: Disregard all formal rules of construction and concentrate on getting the job done rapidly by using any method.

JICPOA,L~50627.,1.THRU 24 PAGE

UNCLASSIFIED I

.1"Xil. UNCLASSIFlE;O, Construction of bridges by emceesive bays.Mathe advantage of requiring few

men, but it has atime-conslmling disadvantage. 'Conversely, the construction ~1 parts takes less time, but requires more men. The Jape prefer the successive bay method,probably because of lower personnel requirements, and use construction by IB rtsonly as the s .ituation dictates.

, '

Two broad plans have been used by the Japanese in crossing large rivers. First J they attempt to move'a complete. unit across on boat.s and barges. Secondq, front' line troops are sent across by boats and barges with the remainder of the unit crossing by bridge. '

, ( Use of the firat plan doe. not necessarily preclude construction of a bridge,

, but. vulnerability to. attacks. from land, 'air and water makes bridges di tficult to defend, .and construction nonnally will' not, be started until front'11ne troops have crossed on boats and secured their bridgehead. ,.-.

In. the second plan, a bridge is built as, rapidly as possible and the croasing is made by combined bridge and boat facilities. .Emphasis is placed on. JIlOvin&. horses and vehicles across on pack horse ,bridges and medium reinforced bridges to assist front line forces in establishing positions. Although an attempt, 'is'made to integrateengineering work with the general situation, priorities .of .1Ork will depmd on'the width of the river, materials on hand and the enemy situation. '

Information contained in this. report has been compiled from. various sources and includes all known types of bridges, boats. and expedients, with illustrations and charts, .use

U'NCLA$SIFlE:D';~ ie",O".' II

ORGANIZATION Available organizational reports and tables leave a saJiewhat conr'using picture

relative to the exact composition of a complete engineer unit, designed' specifically for bridge ,building and river crossings. OneJtable lists 220 officers and men ina bridge building canpany while another shows 400 and a third indicates more than 60J persmnel. Larger units, are hor8.e-equip~d, smaller 'ones a:r:-e motorized

.Each Japanese'division contains an engineerre~t or its equivalent,ana.logous to the U.S. Amy Engineer battalion in number o/men, but not in the amount of. equipment carried~ . The unit normally consists of. three field companies .arid a regimental material platoon.Regimen~8usually bear the number of the division to which they are attached: the 15th Engineer Regiment.wouJ.,dbein the 15,th Division.

, Captureddocuznents bear out the beli.ef' 1;,hatall Japanese engineer regiments are organi'zed 'with at. least one bridge building company, or with enough fiexibility to fornl the equivalent.,cerone b.ridg~ building canpany fron! trained personnelwlth'in the varioufJcompanie8~r"theregiment.

"

Chart A

c

s:()z

.cn~ .ClJ: .......

-n:-m 0'

P~RSONNEL NEEDED FOR VARIOUS rr'YPES OF CONSTRUCTIONV.ITH TYPE 100 'AND VEHICLE-TRANSPORTED TYPE nB" RIVER CROSSI~MATERIAL

-

s;

Classifi-'

cation Type 100 Vehicle-Transported Type "B" ...

+Method J Trestle

Br~dge SingleFloat'

End to End Raf,t

End to End Raf~-Beam

to BealIl Trestle Bridge

-Ponton End to :bnd

Raft End to End ~ ~ Type . J: Personriel

Leader Men Leader Men Leadel Mep Leader .Men -.

Leader Men Leader .Men Leader Men

~ 1st Sec. 1 6 / 1 12 1 10 1 1 12 ~ 2d Sec. 1 6 1 12 1 10 1 1 12

~ 0 3d Sec. 1 6 1 12 1 10 1 12+' t,: 0 4th Sec. 1 10

Po. 5th Sec. ," 1 10 ,. "

Upstream Required Personnel 1 6 Anchor Sec. . . Downstream' Anchor Sec. 1 ,.' 6 1 6 1 6 1 6 1 6 1

..

6 1 .

6 Girder Section '. 1 10

"

1 14 1 9 1 9P+anking Section 1 16 1 16 1 9 1 9 Bridgehead Section 1 9 1 9 1 6 1 8 1 11 1 11 1 7 Reinforcement Section 1 9 1 12 1 12 .

Boat Handling Section 1 6 1 6 Trestle Placing Section 1 8 1 6 Trestle Tpt. Section 1 7 1 6

T OTA L S 71 ,

8 75 6 60 7 64 7 53 7 41 5 49

,UNCLASSIFIED ~t2 n"21,111// BRIDGES

Brid.ge building and river oro8~ing operations are likely to be a significant factor in Japanese tactics of future campaigns. Techniques of crossings set- forth in this chapter are ~f logistical and technical' importance as well as tactical. Thus tar there have been no reports or the, enemy making an assault crossing, al

though captured document s indicate they are equipped to do so.

Considerable information has been obtainad on bridges and bridge building.in general .from captured documents, PhotOgraphs., prisoner., of .war reports and re,p.orts from observers. However,iJl only one case (an eye-witness report franBumaJ has it been possible to follow the a ctualconstruction .or a bridge through its many

, cOlIlplex steps. Using our own bridging procedure as a guide, thef'ollowing notes, togetherwfth photographs and charts, represent the available information on Japanese bridges and bridge building.

The bridge reported by the eye-witness was used by the Japs to move foot troops, porters, animals and handcarts across the 400-yard wide Chindwin River in Burma.

Rafts consisting of six boats each were' joined end-wise tofOrDl' a continuous length of bridge as long as the Chindwin was wide. , The down-stream end of the bridge was picketed to the bank and the upstream end was pushed out into the river until the current ,carried it to t~e far, bank, where it was picketed into position.

The floats for this bridge apparentlyweref'aetory.l.made, _ss-produced wooden boats with blunt bows and stems. They were approximately eight feet long, four teet wide and ,two and one half feet deep. All. were painted black and had what were believed to be fittings for outboard motor attachment, although no motors were seen.

Each boat had eight steel brackets, four on each gunwhale, through which bamboo balk was fitted. The balk ,spanned t'WO bJats, 'the two-toot interval between,' boats,

, and ovetlapped the next boat b7 the boat's widt~. , .

Flooring was timber made up in p,anels,approximately eight feet long and five teet wide, and weighing between SO ~d 100 pounds. The, panels were laid directJ.3 on the back andwer,e not lashed down.

Two other bridg~s constructed by the .Japanese in Burma were a mule bridge and root bridge over the, Turel" River near Imphal. Trestle bents for' the mule bridge consisted of' old car chassis with stringers andfiooring made of bamboo ,am 'l.ooden poles. The root br1.dge.was made ottripodpiers, stringers and wooden decking.

One prisoner hasstatedthatthest.andard foot bridge used by the Japanese consists of board or bambOo slats (presumably decking) abo'ut five feet long, placed on rubber boats. The boats, are spaced across the river in 13-footinterVals. Duck boards for this bri~gearethree f'eetwide to support trpopscrossing in single file, and five feet wid~ to support trQops in columns of twos or threes

PAGE.UNCLASSIFlf;P 5

UNCLASSIFIED ,CO{OiR'

I I Figure 1.

'.

Figure 2.

Figure 3.

PAGE 6

UNCLASSIFIED

UNCLASSIFIED

Figure 4. II Figure 5.

The bridge shown in Figure 1 is designated b~r the Japs as their Type 97 foot bridge. It seems to fit the prisoner I s description of a canmonly used foot bridge.

When it became necessary to increase the capacity of bridges, due to increased . weight of ordnance, the Japs developed the Type lCX) bridge illustrated in Figure 2. This bridge wiD accomodate vehi.cles and artillery pieces up tol seven tons.

The Type C vehicular bridge S10wn in Figure :3 is used chiefiy to support any

thing up to and including medium tanks (16 tons). Except for the bridging pontons, the entire bridge is constructed of steel.

No type number has been given to the bridge shown at the left in Figure 4, although the text accompanying the photograJil states that it has been constructed from new heavy bridge equipnent and will carry caterpillar-tread vehicles and field vehicles weighing up to 20 tons. A Type 97 single file foot bridge is at the right in the phot~graph. A medium tank is pictured crossing a river on new type vehicular bridge in Figure 5.

The Japanese are sldlled in the construction of wooden trestle bridges which they erect speedily fran materials prepared beforehand or available locally. Joints in these bridges are usually lashed witb straw rope ,and occasionally are strengthened with iron pins. Such trestles are found serving as approaches to ponton bridges in wide river beds. In shallow rivers the bridges may be several hundred feet in length. Despite their flimsy appearance they are capable of supporting artillery and heavy equipment.

A report from the New Guinea area states the Japanese have used a light, easily handled miniature truss-type bridge of steel tubing with wooder1 treadways.

When three spans of this bridge are Joined, the center 8~n can carry 700 pounds without appreciable sag, and the bridge, even when joined in iengths of four and possibly five spans, will carry without reinforcement a steady stream of troops

UNCLASSIFIED PAGE 7

UNCLASSJFJED at ordinary intervds. Two such bridges, laidpar~el, wo~d carry,wi.thout, reinftrcement a dead weight of 3,000 pounds in lerl8ths ,up to t,.h.ree spans. "A small vehicle up to the weight of a jeep could negotiate the parallel structures, and light field artillery could cross easily. If,reirl!orced,thebridge" of course could carry weights ,up to the bearingcapacftyofthewooden treadways.

The actual ,,:,sight,of a complete bridge ot three sections is 154 pounds; ,it can ~asily pecarri,~ by two men. , A five-se~tion ,unit could be carried by tw,o men, although the length would, make it ,8 clumsy, burden. I , ,

" ' "The bridgeisllladeupof endspans,vbich have carrying handles, and center spans. ,Each end 'spanfsll'feet6inches long; each center span is 9 feet long. The depth at a.' center span is 9!inches. The enci spans have nine bays, seven or "trl.ch ,' carry treadway's" and twoot which tenninat e in carrying handles. The center spans have seven bays, a.ll or which carry treadway.

Charts B, C and Dcontain pertinent"dataonJapane~e'bridgingmaterial, capacity of bridges, and classification 0 t various bridges.

Cl:iARACTffiISTICS Qf. ~.,.~ EQUIPMENT, ~ 1: ~

Classification

Special River

crossing !!a~, terials (Im

proved types)

Type'A ," Vehicle

carried River

Crossing Materials

3Ponton Bridge

4Ponton Bridge

Ar:" ra2gement

l

Arrange-

Capacity

Gross weie';htunder 7 tons.Ve,hicles with 'axle. load less than 5 tons & space between axles of over 9.84 :n; and tracked vehicles of over 6.56 Ft. @'round cont.act. Gross l/Ieil!pt, un';' del' 16 tons. Vehides with ~e load below 9, tons and space between axles above 9,84 Ft. and t~acked i vehicles above 9.84 Ft.. ground contact. !;led Arty (under ,10cmGun, ,tractor drawn), ,vehiclesunder2 tons axle load, " 3 tons gross weight. Tractor-drawn 10cm Gun, 4

ment ' ton truck; 2 othe~ vehicles

under 3-ton axle load, over 9.84 Ft. space between axles; Gross ',it. under 5 tons. '

Length Organization of of 'one Bridge Materiel Co one liat Co can build 929;9 'Yds.

168;48 Tptliagon Yds. (4-horse

drawn) ': 94

Draft Horses Yds.

136.75 384

Reserve ,Horses:

24

I"

Notes

1. Use light hand-drawn carts. 2. 1oieightof pontons .(4section steel pontons) 6174'Lbs.

~etal Pon

tons (2

. sections)Total Vit: 1543.5 Lbs.

PAGE 8

eSNIlffiIO i lAC

Chqrt B, (continued)

CHARACTERISTICS OF RlVER"':CROSSING EQUIPMENT,_ PART I: BRIOOING

(Continued} Type A Vehiclecarried Rivercrossing Materials

Type B VehiCtle-' carried Rivercrossing Materials

"

Type C Vehiclecarried Riv~r" 'crossing Mciteria1a

.'

,.

Arrangernent 3

Ar-rangement 4

Tanks, Ground contact over 9.18 Ft; gross wt under 10 tons. Tanks, ground contact;, over' 12.46 Ft; grosswt under 16 tons.

Single Med Arty (inclulane 'ding Type 3810 Bridge cmgun in tra

veling condition) Vehicles under 2. ton axle load, 3 ton gross wt.

Heavy 4 ton trucks Single ,Vehicles up to 'lane 5 tons gross wt;

Bridg~ when axle load is under 3 tons and space between ,axles over 9.8L.. Ft. 'When current of stream is slow, can barely ,ca:r,ry tractor-dra.wn '

. IDem gun

(ggldL ,a2;,)lP4;g ,:U~NGbASSIFIED ctt6rt,'S(ci>'ntinuecJ)

,CHARAOTffiISTI OS OF. RIVER-CROSSING EQUIPMENT PART 1.: . BRIDG!NG

(Continued) Type 100 Ar Gross wtunder River.... range 4 tqns ; vehicles crossing ment axle load under Materials 1 '3 tons; space

between.axles over 9.84 Ft; tr:acked vehiclesground--contact ov'er4.~2 Ft.

164.1 Motor truck Wt of metal Yds. about 130 pontons

(3 sections) 1808.1 Lbs.

Ar Gross wt under range 7 tons; vehicles ment axle load under

2 5. tons, space between'aXles over 9~84 Ft'; tracked vehicles .... over 6.56 Ft~(up to light tanks).

Type 97 Single liJlepf' 54.7 Motor truck FO,ot infantrymen Yds. I Bridge with equipment AlsoTpt Materials Wagon '"'!'5 RRRiver

,Crossing Materials

Emergency Bridges_ (Using experimental

. materials I for'1094

Yds river' bridges)

I

I: I ,

Motor River-Crossing Ferry for RRCars

.For Heavy Trucks \

........

For Light Trains "

car ;

Ferrying Fac.ili.... ties

Type 99 .RR Bridge Trussed Girders 30 sets (plusco'nstruction tools) FUlBridge .Supports (largest). 31 sets (Not used when legs of bridge are low)RR Bridge Piles (largest) 15 sets (Not \lsedwhenthere is no current) Type 99RRBridge Trussed Girders 15 sets (Use aqout half sleepers (or ?) rails).' ... ' .... ( RRBridge .'. Supports (largest) .. 15 sets (not used when .legs of bridge are low) RR'Bridge"Piles (l~gest) 15sets (not used when there is 'nocurrent) ' Embarking facilities -. both river banks River crossing motor fer,ry 2-3 l(p9c;i{....ciowntype transpprt equipment-as needed' for the above. '

PAGE 10

.UNGLA$SJFII:D

UN~~SlPI:eO -ChartC

CAPACITY OFBRIOOES BUILT. FROM VARIOUS STANDARD TYPES OF RIVER"'croSSING .MATERIALSff

Classification Capacity Remarks' 'Type 97 Foot Bridge Single file on foot at

2 or 3 paces interval Type Small Ponton Bridge Single file on foot, For 13.12 Ft. span 91 Medium Ponton Bridge Double file on foot For' 9.84 Ft. span'

Large Ponton Bri~ge Triple file on foot For l3.l2Ft. span Horse 3-fi1e colu,mn' of forces on Carried foot or Mtn Arty (limbered) Bridge :width-Light'BridgeType 7.872 Ft. RCM

"

T~Tpe Tracked vehicles of gross-. 100 Heavy Bridge weight up to 7MT or wheeled Bridge width-

RCM . vehicles up,to 5MT' 9.84 Ft. Vehicle Bridg~ width-

Carried

1st MethQ9. All unit~ of Fd Arty ( except 9.84 Ft.

Type "A" those organized for motor transport) All. vehicle s of

RCM gross-Weight up to 3MT(sin

gle axle load 2fu"T) ~d Method All vehicles off,ross-weigh:t "Same as above

'.

up to. 5lvlT (single axleload-3M"T) ~

,3d Method Tracked vehicles .--Max. , lOMT, Same as above 4th Method .Same as above

Vehicle

Tracked vehicle's.--1~.16MT

Medium Bridge Vehicles up to 3~T Gross Wt. Bridge width-

Carried 9.184 Ft. Type "B"

"

Heavy Br.idge Vehicles up to 6T Gros,s Wt. Same as above RCM Vehicle... Self-prop,elled Carried

Light-:-Heavy Vehicles up to 161IT Gross Wt~ vehicles only.

:r'ype "Gil RCM Special'

DutJr Bridge

: Tracked vehicle s. of gross

RClv:

Light : Bridge 3 Line'

cles of single axle load up weight up to 7MT'. All vehi

'Bridge Pontons , to 3T. ' width-

.........,:.----------1-................-----------------1 15.088 '~4~L~i-n-e----IHeavy Trackedveh,icles of

II P UNOLASS1FlED, , " ..,' " ',-' -,' ,.,.', .. -.;. ~""., -,.

ChartD

NUMBER OF COLLAPSIBLE BOATS REQUIRED BY A DIVISlOOIN RIVER CROSSING,

, Craft RequiredDistribution Number Remarks

Force ~ 15 boats 142 men will be loaded

Hq PersonnelDivision

212 boatsHorses 48 boats lIith'the automobiles Automobiles 149 boats and horses.

Division 44 men will go aboard Signal.

18 boatsPersonnel 78 boats with the horses and

Unit Horses, 6 boats

transport vehicles. 35Transport 54 boats horses will'be loaded, with the transport vehicles.

Infantry'

Vehicles

6 boatsPersonnel 26 men will be loaded,27 boatsHqrsesGroup 21 b,oats with the horses. ~Hq (DAN)

Infantry " 2200' men and 28.0 horses Regiment

,261 boatsPersonnel' ,1,566?oats will be loaded with the

Rifles ' Horses 822 boats

transport vehicles. Guns

3 formations36 boatsIe boats (4698) boats

,

'Transport I520 boatsVehicles

" ",

33 boatsReconnaissance Personnel About 306 men will get Regiment 147 boats 384 boatsHorses on board with the auto

204 boatsAutomobiles mobiles and horses. ArtilleryGp

"

,Personnel 90 men ~illgeton board Hq (DAN) ".

9 boats I with,the horses, and tr-

Observation Horses 54 boats

ansport'vehicles. 1896.boats6 boats ", ,horses will be loadedCars

) with the transportTransport 27 boats vehicles.Vehicles Entire personnel will

Regiment 306 boatsPersonnelFA

get on board with the Guns

1620 boats -:Horses 216 boats guns, "horses, and

Ammunition "

vehic~es.2,757 boats396 boats Carriers

,Reserve 39 boats Vehicles

,

'Observation 66 boats Cars " Transport 420 boats Vehicles

J 2878 men will get on Artillery

Personnel 78 boatsMountain board with.thehorses,Horses. lIaS boats ,

2,200 boats guns and., transport Transport

lOS 'boatsGunsRegiment vehicles. 508 horses822 boats 'Will be loaded with the

tran~port vehicles. Vehicles .'

"

PAGE 12 UNCLASSIFIED

UNCLASSI.FlED ~.n rUdtl" Chart 0 (c'ontinued}

NUMBER OF. LLAPSIBLE R>ATSREQUIREDBY A DIVISION IN RIVER CIDSSING - (ContI d) . I '.

Required RemarksDistribution~ Number

, ..---;::l '-------,---------;----:..----+-------------1157 men will get on boardEngineer Personnel

,Horses with the horses, automoRegiment 69 boats 205 boats biles and transportveAutomobiles 16 boats hicles. 30 horses willTran~port 45 boats be loaded with theVehicles transport vehicles.

Transport Personnel Regiment

......-:-H_o_r....s_es~~--+-AutoJIi..obiles Transport Vehicles

"

186 boats __1~6_:'8-b....o-a-t-s---1l,828 boats 568 boats'

1092 boats

Entire personnel will get on board l'litl). the horses, automobiles, and, transport vehicles. 727 horses will be loaded with the transport vehicles. Goods to be' loaded in excess. of estimate (ammunition rations and forage ~

Decontamination Unit 93 boat'sAutomobiles 81 boats

Personnel 12 boats 42 men will get on board with the automobiles.

Ordhance DutS' Unit 52 boatsAutomobiles 43'boats

Personnel 9 boats 22 men will get on ooard with the automobiles.

Medical Unit

Personnel . 81 boats ~H__or__se....s__~--+-~~5~1-....bo-a-t-s-'_'_'I 297 boats Automobiles 153 boats Transport 90 boats . Vehicles'

260 men will get on board witb.,the,automobiles., ,'horses and transport vehicles. 60 horses will be loaded with. the transport vehicles.

Field Personnel 15 boats Hospital ......H_o_r_se_s -+-~..l_2-b....o-a-t-s--_I123 boats

Transport 96 boats Vehicles

Veterinary Depot

Personnel Horses Automobiles Transport

JA3 men will get on . board with the horses and transport vehicles. 64 horses will be loaded with the transport . vehicles.

6 boats 82 men will get on board 15 boats '. 83 boats with the horses,automo20 boats biles and transport ve44qoatshicles. 27 horses will

Vehicles' be loaded with the " transport vehicles.

Hygiene and Personnel 18 boats 117 boats 66 men will get on board Water Supply Automobiles 99 boats with the a.utomobiles. Decision 'IO TAL: 1,3 ,250 boats (165.6 formations) . .'

166 Rubber Boat Units required by a Division in River Crossing Remarks - 1. Method.of 'embarkation will,beacco'rding to the appendix in "Regulations

onRiver Crossing Work. II Trucks, will be loaded ona raft of four boats. Two"transport vehicles and two 'hor~es will be loaded on a raft of three boats.

2. Only single boats are indicated when accouriting i'ornumber of craft

PAGE 13.UNCLASSIFieD

""0 l>

Chart E G> fTI .' TABLE OF MATERIALS USED III PREsENT JiEGULAR TYPE RIVER CROOSING (BRIDGE ONLY)

ta '.

I\Classiflcation~

Special River CrolllSing. \ Equipment

....~ Z Vehicle ): () . Transported T~ "A" River

Cro~singCIJ Material C.IJ-"TI'.....,..

m, 0

Vehicle . Trans

ported. Type "B" River Crossing Material;

Horse, Trans

ported Type River Crossing Material

Condition or River T() Permit -Oon-I---!!~'II't..ll&.+-. ..~I~..n~"+~w.I\'a.-,~."...-~

~..tle Pcm,t(Ui Bridge Bridge

Depth. or Water: Over 31.49 Inches

Water Depth of Depth: Water: 6.56 Ft Over or leS8. 23 .. 62 In. ForrI! and IV" Current 4.92Ft Rate: orles8. 2.5 MPH

or less . Current Rate: 1.5 MPH or less

.

Water Water Depth: Depth: 6.56 Over Ft. or 19.69 less. Inches. Current Current :Rate: Rate: '1.5 MPH 2 MPH or' less. 0t: less.

Water Water Depth: Depth: 4.92 19.69 Ft. or Inches less. or Current aore. Rate: 1.5 MPH or less.

Length of bridge Width Principal Principal Length of whIch can be made . or Materia18 Equipment -Bridge ~om. equipJl!8nt. Bridge needed for of one ~y of one Materials one Bridge llaterials (Span) . Company Bay (Engineers) Company I.' (TN=-- See expla.. 15.09 Trestle. Br: '. Capsill :2 Sets Abut Tre.stle nation at bottom Ft. 1, . Girder,S, planks ment, For Bridge: forI,'U, III &: 20, Guardrail 2, Tree.tle Br. Ordinarily IV) ,nal.52 Yds. lashings 6. Ponton 22 Bays, For' 16.40 Ft.

Br: .lIetalPontonl, PontonBr: Ponton II. 929.9Yds ..

, ~ .. .

c: z o s;: CJ) 'A .\,1.1

-

.."

ii 0'

Vehicle' Trans-', portedType "C River Crossing Material

Water ])epth:

..9.84F,t orless. Current Rate: 2.511PH or less (When' water depth is 6.56 Ft. the rate will be 2 MPH or less)

Wa1ler Depth: 7.S? Inches, or over. Current Rate: 2.5 MPH or les~.

76.58 Yds.

7.S? Ft.

Trestle Br: 1 Set of trestles and 1 Sllperstructure, Ponton Br: 3 piers

, 1 superstructure, ~ anchors, 3 anchor ropes. .

4 Sets Abutments, 6 Bays for Trestle Bridge, 4Baya for Ponton Br.

Trestle Br: 22.96 Ft. Ponton Br: 22.96 Ft.

It iS'necessary to allot one Line of Communications Transport ,Company

1'ype 100 Water Water 9.84 Trestle Br:1 Set 3 Sets Abut Trestle Br: About 150 . About River Depth: Depth: Ft. trestles, 7 girders, Jlients, .9 sets 13.12 Ft. trucks 11359.8 Crossing 4.92 Ft 19.69 16 p4nks, 2 guard trestles, Pon Ponton Br: Yards Material or less. Inches rails, 6 lashings, ton pier 33, 13.12 Ft.

Current or over. I transverse girders 44 sets superRate: Current 1, 2. sets supports. structure ma1.5 MPH Rate: Ponton Br: l'lIetal terial, anchor or less. 2.5 MPR bcl8t, 4 lashing nets boats 3, ro~

or less 7 girders, 16 planks boats 15, sIt!2 guard rails, 4 cia! anchor :3. lashIngs, 2 cross bracings, 1 trans

.verse girder, 2 anchors, 2 anchor ropes. . .

TYPe 91. Suitable Girders for sections 104.96 aneset'is Trans ,'for high 36, girders for ex Ft. the material verse ~'and tremities.8, ordinary allotted Girder steep planks 140,22 hand for one 'bay. Road streams rails,abutment ) Bridge. arid

rivers. material 4, .abutment stakes 40.

Type 92 Same 1],.48 Girders for sections 98.4 Same a8 Trans as Ft. 64, girders for ex Ft. above. verse . above. tremt~es 16, bridgeGirder planks 140, 22 handHeavy rails, abutment maBridge. terial,4, abutment

stakes 40. Type 97 Footbr1clge

Current Rate: 1 MPH or less.

. River 'iidth: 109.4 Yds or less.

23.62 In.

2 Superstructures 2 Transverse Girders 4 Floats

16.4 Ft.

One set is material allotted for 10 bays

The numbers I, II, III, &: tv indicate the method of' construction corresponding to the, resistance strength.

'!'here is no transport equipnent. Such will be allotted as needed.

EIPLAlIATIOIf:

(j1

UNCLASSIFIED &To: )rs2itii42

IV BOATS

Several different types of boat s have been developed by the Japane se for use in crossing rivers and streams. These boats should not be confused with standard assault boats sometimes used by the Japs for river-crossings.

Ideal boats for moving troops and materials across rivers are either collapsible or demountable models: One collapsible. boat in wide use is divided into two sections, each of which collapses flat upon itself and is individually floatable. Each section i8 13! feet long, 43/4 feet wide, and slightly more than 2 feet high. The wooden frame is braced and all joint 8 are bonded wi th rubber. This boat will carry 20 men and nine such boats can be loaded on a t1fo-~on truck. Light outboard motors have been used to propel this boat.

Japanese engineers operate a variety of demountable motor boats, fitted with outboard and inboard motors of various kinds. One small, .3O-foot boat normally propelled by an outboard motor breaks into four sections. Some of the motors are arranged for animal pack.

Three types of rubber boats, of from one to ID-man capacity, are known to be used by the Japanese for river and stream crossing. No data is available on these boats, but they are thought to be similar in construction to tmse used by U.S. forces.

In many situations bridge ~nstruction is impossible and the Japs will be forced to depend upon boats and ferries to get their men and equipment across rivers. Chart E gives an excellent picture of the number of collapsible boat s required to move a division across a river.

Figure 6 is an illustration of a Type 95 three-boat raft used exclusively for river crossings by oar or motor propulsion. It is collapsible and can be carried on transport vehicles. Capacity of a three boat raft is 14 men, or 11 men, one battalion gun and five ammunition boxes. Another three-boat raft Used far crossing vehicles is the Type 99 heavy raft shown in Figure 7. Weights up to 15 ton can be carried on this raft. It is usually propelled by motor and can be trans ported on motor vehicles.

Figure 7.Figure 6. PAGE 16 NCLASSIFIED

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V SWAMP CROSSING

Japanese ingenuity has received full play in developing methods to move men and material across swampy terrain. A small amount of equipnent has been standardized for this phase of operations, although enough latitude has been extended for many expedients.

Most swamp crossing equipment encountered has been compact, light, and carried by the individual or on his vehicle. Approaching wet or swampy ground that threatens to bog down both troops and equipment, the Japs first measure the resistance and depth with the apparatus shown 1n Figure 8.

Figure 8. Sketch 1.

Swamp shoe s are cOlIDllonly used by foot troops to cross over soggy ground. These are made by the individual soldier from rattan, When available, or iron wire, willow and other local materials. Sketch 1 illustrates the oval-shaped shoes, which are 15 to 20 inches long and 12 inches wide. Heavy rope, ribbons and string fasten the shoes to the feet, and poles, similar to ski. poles, aid in supporting the individual.

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, Sketch 2.

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Another type shOe is equipped with buoyancy bags (Sketch 2) am is used by the Japs to cross small streams as well as swamps. The shoes are slightly more than 5 feet long, 6 inches high, weigh approximately 20 pounds and have a buoyancy of 290 pounds. These shoes are big and clumsy and their standardized use is doubtful.

Sketch 3 illustrates one of many methods of transporting artillery and other heavy equipnent acro ss swamps when road construction is inconvenient. Wooden sleds weighing approximately 100 pounds each are used most commonly.

Planking laid over rubber ponton boats frequently is used to move troops and ordnance lighter than field guns across watery stretches. These bridges are light, easily transported, and can be quickly assembled.

Wheel treads are a common expedient used to move heavy artillery pieces.

Figure 9 shows a Type 38ilJ\'! 75 mm field gun equipped wi. th wooden t reads which fit over th e rim of the regular wheels. Iron treads also are used.

~lat roads made fran rattan, bamboo, mat-rush and other available materials are used ext.ensively. The slats are bound together and rolled up. A hurdlelike pusher is attached and used to unroll the road over the swamp area to be crossed. (See sketqh 4).

Figure 9.

Sketch 4.

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Type 97 Foot Bridge.

Japanese soldiers employing small rubber raft in practice river crossing.

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