tank destroyer pioneer platoon
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WAR DEPARTM'ENT FIELD MANUAL
TANK DESTROYERPIONEER PLATOON
WAR DEPARTMENT . NOVEMBER 1944
RS aQ ZID ED
WAR DEPARTMENT FIELD MANUAL
FM 18-24
TANK DESTROYER
PIONEER PLATOON
WAR DEPARTMENT NOVEMBER 1944
United States Govarnent Printing Office
Washington: 1944
WAR DEPARTMENT,
WASHINGTON 25, D. C., 1 NOVEMBER 1944.
FM 18-24, War Department Field Manual, Tank De-stroyer Pioneer Platoon, is published for the informationand guidance of all concerned.
BY ORDER OF THE SECRETARY OF WAR:
G. C. MARSHALL,
Chief of Staff.
OFFICIAL:
J. A. ULIO,
Major General,
The A4djutant General.
DISTRIBUTION:
T of Opns (2); All SvC(2); Depts( 2); IslandC (2); Base C (2); Def C (2), Sectors (2), Sub-sectors (2); Base Sectors (2); HD (2); B 18 (1);R 18 (1)-; Bn 7, 18 (5), except I Bn 18 (20).
I Bn 18: T/O & E 18-25.
For explanation of symbols, see FM 21-6.
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CONTENTS
Paragraphs Pages
Section I. General… .................. 1-3 1
II. Pioneer reconnaissance … ._. ... __. 4-7 3
Ill. Movements _...._____._.___ _ 8-14 9
IV. Bivouacs . . ... _ ........ 15-21 19
V. Position in readiness … . ....... ___ 22-24 30
VI. Combat area -- ___.._____.______ 25-28 32
VII. Technical training _________ ._____ 29-30 36
VIII. Safe strength of equipment ------- 31-33 38
IX. Road expedients ................. 34-37 41
X. Stream crossing expedients . .....- 38-41 46
XI. Bridge strengthening … .-----_-__-__ 42-47 52
XII. Determining capacity of bridges … ... 48-50 64
XIII. Deceptive measures ___._________ 51-53 76
XIV. Mine removal …___________________ 54-56 80
XV. Bomb and artillery dud disposal … ... _ 57-58 87
XVI. Estimation of demolition charges ---- 59-63 90
INDEX --___........................----- 97
MI
Section I
GENERAL
1. ScopeThis manual covers the tactical employment ofthe self-propelled tank destroyer pioneer platoon.It is designed to be used as a guide only and doesnot provide inflexible rules. All commandersmust be encouraged to solve each situation ac-cording to the various factors involved.
2. EquipmentThe pioneer platoon is organized and equipped toaccomplish small construction and demolitiontasks. The text and illustrations contained here-in are based on tables of organization and equip-ment in effect at the date of writing. These tablesmay change at any -time; however, the methodsand principles described in 'this manual will still beapplicable.
3. Missiona. The pioneer platoon 'has two general mis-
sions:(1) To prevent the movement of the battalion
from being delayed by natural or artificial ob-stacles.
(2) To impede or canalize the movement ofthe enemy by the creation of obstacles.
b. Quickly executed field expedients, ratherthan extensive works or improvements, are thenormal 'tasks assigned the platoon.
Note. For military terms not defined in this manual seeTM 20-205.
c. The personnel of the pioneer platoon aretrained to accomplish many tasks, some of themore common being-
Strengthening bridges.Improving fords.Making minor road repairs.Clearing road blocks.Making passages through mine fields.Neutralizing booby traps.Assisting in the preparation of gun posi-
tions.Improving fields of fire.Constructing road blocks.Increasing the effectiveness of natural
obstacles.Laying or removing hasty mine fields.Performing limited demolitions.
d. In addition to the above tasks, they are alsotrained to fight. They must know their weaponsand be able to use them. At times, it may benecessary to fight in order to accomplish the pri-mary mission; in emergencies, the platoon may becalled on to cover by fire obstacles it has preparedor to reinforce the small arms fire of other groundtroops.
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Section II
PIONEER RECONNAISSANCE
4. GeneralSelected members ,of the pioneer platoon usuallyaccompany elements of the reconnaissance com-pany on route reconnaissance. The reconnais-sance elements report the location of the roads,bridges, obstacles, and similar items; the membersof the pioneer platoon report the condition ofthese items. All obstructions are investigatedand reported to 'the reconnaissance companycommander.
5. Missionsa. Some of the more common technical matters
to be investigated and reported by pioneer recon-naissance elements are enumerated in the follow-ing paragraphs. These lists are to be used asguides and should be modified as experiencewarrants.
b. ROADS (FM 5-10). (1) Capacity, includ-ing possible effects of rain or snow. Can the roadsupport the heavy vehicles df the battalion underall probable conditions?
(2) Obstacles and an estimate of the work re-quired to reduce them (FM 5-30).
(3) Wood, gravel, rock, or other materials inthe vicinity which could be used to repair the road.
(4) By-passes around obstacles -if the road can-not be cleared or repaired in a reasonable lengthof time.
c. BRIDGES (FM 5-10). (1) Construction,
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to determine the weight the bridge will bear.Bridge cards (par. 49) will be of assistance.
(2) Conditions 'of the approaches, to deter-mine whether or not they can be used safely bythe vehicles of the battalion.
(3) Repairs needed -to the bridge or the ap-proaches before the battalion can safely travel onit. (sec. XI).
(4) Materials in the vicinity which may beused for repairs.
(5) Presence of demolitions and booby trapsand an estimate of the work required to neutralizethem. This mission is especially important in ter-ritory which has been occupied by the enemy.
(6) Possible effect of a swollen stream or aheavy rain on the bridge and its approaches.
(7) By-passes that may be used even thoughthe bridge will carry the battalion; enemy actionor weather might render the bridge impassablebefore the battalion has used it.
(8) Time and material needed to destroy thebridge in the event this action should later becomenecessary (sec. XVI).
d. FORDS. (1) Approaches to ford sites, todetermine whether or not they will support thevehicles of the battalion. If possible, the ap-proaches should be perpendicular to the streamfor at least fifty yards and should provide coverand concealment for the vehicles if there is anypossibility of enemy observation. The exit neednot be exactly opposite the entrance but may bea distance up or down the stream.
(2) Depth of the water in relation to the ford-ability of the vehicles of the battalion (par. 38).
(3) Condition of the stream bed to determine
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whether or not it will bear the vehicles of thebattalion.
(4) Work necessary to prepare the approachesand the stream bed for use (par. 38).
(5) Materials in the vicinity which can beused for necessary repairs.
(6) Possible effect of changing weather condi-tions on the stream bed and approaches.
e. CROSS-COUNTRY ROUTES. (1) All barriersto the movement of the battalion such as woodedareas, soft ground, streams, mined areas, traps,etc.
(2) Work required to make the route passablefor all vehicles of the battalion.
(3) By-passes around any barriers requiringan excessive amount of work to reduce.
(4) All opportunities to impede enemy at-tacks, such as the possibilities of mining or con-structing obstacles in likely avenues 'of approach.
f. MINED AREAS. (1) Location and extent ofmined areas.
(2) The presence of booby traps in and aroundthe mine fields.
(3) An estimate of the work necessary to cleara path through the mined area or the possibilityof by-passing the mine field (sec. XIV).
6. Road and Bridge Guardsa. The capacity of bridges, fords, and other
critical road sections is substantially increased andthe required maintenance greatly reduced by con-trolling the speed and interval of vehicles at thesepoints.
b. When tank destroyer vehicles cross points
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which have a capacity equal to or only slightlygreater than the weight of the vehicles, the maxi-mum speed should be five miles per hour; the in-terval between vehicles should be at least 50yards. A constant speed should be maintained.
c. Bridge guards should be stationed at criticalpoints to enforce orders necessary for safe pas-sage. The pioneer element of the reconnaissanceparty reports the number and locations of guardsneeded.
7. Pioneer Reconnaissance Reportsa. To be of value, the information secured by
pioneer reconnaissance elements must be returnedto the appropriate headquarters in sufficient timeto be used. This information must be clear, con-cise, and accurate. Information obtained bypioneer reconnaissance will ordinarily be incor-porated into the regular reconnaissance report.
b. A common means of reporting informationis by overlays on maps or aerial photos to showthe location of roads, bridges, mined areas, andother items. Notes on technical information maybe placed on the overlays. When maps are notavailable, sketches may be used. An accuratesketch can be made by the use of a compass andthe odometer of a vehicle.
c. To insure against omission of important de-tails, forms may be prepared for reconnaissance.Forms cannot be prepared in advance to cover allsituations, nor will they always be available in thefield: FM 5-6 gives guides for reconnaissance.Figures 2 and 3 show sample forms for recon-naissance.
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LA MONTEDU CHAPEAU
·'--J' //a/ X I'a
_ · o- I/ , .i ' 1_
Figure 1. Information reported by means of a sketch.
0
0
Figure 2. Information reportedg r oad informatich.
Figure 2. A farm for reporting road information.
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Pigurc 3. A form for reporting bridge information.
Section hIl
MOVEMENTS
8. Platoon MissionDuring the movements of the battalion the pioneerplatoon will frequently move at the rear of thesupport of the advance guard. Its mission dur-ing movements may be divided into two generalclasses:
a. To protect the battalion from delay by re-ducing obstacles or by constructing by-passes.
b. To 'impede or canalize the enemy by con-structing obstacles such as road blocks or minefields.
SYMBOLS POINT
C^RARMOR£Ou ILITU MO2
- C7UK I/ TOSNS
PI OE PLATOONI S
PIONEER PLATOON
DIRECTION OFMOVEMENT.
Figure 4.
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9. DutiesThe following check lists for duties performedprior to and during movements are given asguides. They should be amplified or modified asexperience warrants.
a. PLATOON COMMANDER. (1) Alerts the pla-toon and issues warning order.
(2) Supervises the maintenance of vehiclesand the checking and storage of weapons, ammu-nition, mines, 'tools, equipment, fuel supply, andrations. (These duties are continuous before,during, and after movements.)
(3) Checks radio net.(4) Inspects the platoon and issues the final
order. Insures that all know the situation, route,and destination; issues overlays or sketches ofroutes when time is available for their prepara-tion.
(5) Checks intervehicular distance in both col-umn and dispersed formations.
(6) Keeps oriented at all times by observationof terrain and map, and by noting odometer dis-tances.
(7) Checks maintenance of prescribed speed.(8) Checks observance of blackout instruc-
tions.(9) Checks clearing of roads and proper use
of cover and concealment at halts.(10) At unscheduled halts, investigates the
cause and reports it to the company or advanceguard commander.
( 11 ) Sees that all vehicles move at resumptionof march-especially at night.
(12) Maintains prescribed contact.
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(13) Reports mine fields.b. PLATOON SERGEANT. Assists the platoon
commander as directed.c. SECTION LEADER. (1) Alerts section.(2) Sees that all members of the section are
thoroughly familiar with their specific assign-ments.
(3) Passes on to the members 'of the sectionall instructions from the platoon commander.
(4) Relays all prearranged signals.(5) Checks weapons, explosives, mines, and
equipment for completeness and stowage; checksmachine guns for adjustment, serviceability, andammunition.
(6) Checks vehicles for maintenance, fuel,equipment, and rations.
(7) Checks radios.(8) Maintains control over section during
movement.(9) Maintains blackout discipline.(10) Provides security 'on march and at halts
as directed by the platoon commander.( 11) Sees that vehicles are properly dispersed
and camouflaged at halts.(12) Sees that one man in each vehicle is
awake during halts at night.(13) Maintains contact with adjacent section
when prescribed.(14) Rotates duties of personnel to provide
sufficient rest for all.d. ASSISTANT SECTION LEADER. Assists the
section leader as directed.e. AIR COMPRESSOR OPERATOR. (1) Checks
vehicle for maintenance, fuel, and equipment.
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(2) Checks air compressor tools for complete-ness, serviceability, and stowage.
f. RADIO OPERATOR. (1) Sees that radio isproperty netted and in operating condition.
(2) Operates and maintains radio.(3) Assists in other duties as prescribed by the
platoon commander.g. DRIVER. (1) Operates vehicle and per-
forms first echelon maintenance.(2) Utilizes maximum cover and concealment
in movement.(3) Keeps vehicle in proper gear so maximum
acceleration can be obtained when necessary.(4) Remains with vehicle when halted, and
dismounts only when directed.(5) Mans the vehicular weapon when alone
with vehicle during halts.(6) Assists in other duties as prescribed.
10. FormationsNormally the platoon will move in a column for-mation with the air compressor in the middle ofthe platoon column. During movements acrosscountry, the formations used are adapted to theground and will vary according to whether othertroops are in the area and to the proximity of theenemy. Two standard formations used by theplatoon are the block and the diamond. Theseformations are designed for security and control.The air compressor will take a position in the in-terior of the formation. The platoon may alsouse other formations, such as the line of sectionsand echeloned sections. Units that have need for
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#COLUMN FORMATION
INTEVALNS ANDD[STANCES NOT
TO SCALE
BLOCK FORMATION
l DIAMOND FORMATION
Figur 5 Pton formation
Figure 5. Platoon formations.
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other formations should not hesitate to designthem. Formations should be practiced until theplatoon is perfect in their execution.
11. Security during Movementa. MARCH SECURITY. While on the march the
platoon commander provides for the security ofhis unit by the dispersal of vehicles, observation,the use of covered and concealed routes, avoid-ance of dust, detouring defiles where possible,camouflage discipline, blackout discipline, main-tenance of radio silence, and the elimination of allunnecessary noise and traffic.
b. SECURITY AGAINST AIR ATTACKS. Securityagainst air attacks on the march is gained by dis-persion and alertness. When road space is avail-able and control can be effectively maintained, in-tervehicular distance of about 175 yards is de-sirable. Movement cannbt cease every timeenemy planes appear, because such halting wouldenable a few enemy planes to keep a unit fromperforming its mission on time. For this reason,instructions as to whether to halt or keep movingin the event of air attack will be issued prior tothe beginning -of the march. The platoon takesimmediate measures for protection against low-flying aircraft by using its own weapons which aresuitable for fire against aircraft. Carbines, sub-machine guns, and pistols are not considered suit-able weapons. All men must be prepared con-stantly for immediate action, but will fire onlyupon the order of an officer or responsible non-commissioned officer. No aircraft will be firedupon unless it has been recognized clearly as hos-
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tile or is positively identified as hostile, or attackswith bombs or gun fire.
(1) When troops halt during an air attack,vehicles leave the road, when terrain and timepermit, and halt under available concealment.Troops not manning antiaircraft weapons dis-mount and disperse; personnel fire all effectiveweapons at the attacking aircraft.
(2) When movement continues during an airattack, vehicles maintain distances on the road, or,
ENEMY
+ + D
4 + '+ +
ENEMY +
Figure 6. The pioneer section as part of a flank guard.
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if the terrain permits, disperse laterally while con-tinuing the forward movement. The fire of alleffective weapons is brought against the attackingplanes.
12. Flank GuardThe platoon or section may be attached to a flankguard. In such a case it may construct roadblocks and lay hasty mine fields (with permissionof higher authority) to assist in preventing theenemy from striking the flank of the moving col-umn. The location of such obstacles is governedby the most likely approaches of the enemy. Theplatoon will remove the mines after the columnhas passed. Mine fields and road blocks willusually be covered by fire, and the platoon maybe called on to help provide this fire.
13. Haltsa. Unscheduled halts may be the result of un-
expected obstacles in the route. In such cases thepioneer platoon may be sent forward to reducethese obstacles. Speed in the execution of thesetasks must be attained so the least possible delayin the movement of the column will result.
b. During normally scheduled halts the platooncommander ascertains that proper security meas-ures, such as the dispersion and concealment ofvehicles and personnel, are taken. He thenchecks the condition of vehicles and sees thatproper maintenance is being executed. N'ormally,all personnel will be busy during halts. Restingis usually done only in bivouac;.
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TREE
BRIDGES
Figure 7. Reduction of obstacles.
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14. Rail and Water MovementsPersonnel from the platoon will be trained to as-sist thb other units of the battalion in the loading,blocking, and securing of vehicles for movementby rail 'or water. The special pioneer equipmentmay be used to cut blocks and for whatever otherpurposes are found necessary. The platoon com-mander, assisted by some of his noncommissionedofficers, may be detailed to inspect the work per-formed by the loading crews of the various com-panies.
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Section IV
BIVOUACS
15. Generala. ENTERING BIVOUACS. When the situation
permits, at least part, and preferably all of thepioneer platoon will precede the main body of thebattalion to the selected bivouac area, accompany-ing the advance reconnaissance element 'or thequartering party. This gives time to make neces-sary improvements before the arrival of the mainbody. During movement into bivouac the essen-tial requirement is speed in clearing the road andin finding cover and concealment. The platooncommander or a selected noncommissioned officershould precede the platoon into the area and beprepared to point out the section areas to the sec-tion leaders. After the road has been clearedand all the vehicles of the main body are undercover, the original platoon positions may be im-proved.
b. PLATOON PLAN. A platoon plan facilitatesthe occupation of a bivouac area. Under ordi-nary circumstances the platoon will occupy an in-terior position; all vehicles halt faced toward theroute of egress. In rare instances, when the pla-toon occupies a portion of the battalion perimeter,the machine guns are dismounted and placed onthe perimeter; vehicles again face the route ofegress. The air compressor will be kept well to-ward 'the rear where it will receive the mostprotection.
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"AlTTALIONMAINTENANCE
RANS.FLATPIO
4/ /'
00S 1 ////n 9
Figure 8. Disposition of platoon in bivouac.
20
16. Prior to Occupation by Main Body
a. GENERAL. There usually will be many tasksfor the pioneer platoon to accomplish before themain body arrives at the bivouac area. Frequent-ly the routes of ingress and egress to the bivouacwill need improving, especially when the routesare muddy because of heavy rain or thaw. Typi-cal improvements include filling ditches, holes, andcuts; cutting down humps or high ground; remov-ing large rocks from the roads; and providingcrossings over small streams. Any unexplodedshells or bombs will be disposed of or marked(sec. XV). These improvements should be ex-tensive enough to facilitate the passage of theheavy vehicles of the battalion.
b. IMPROVEMENT OF TRAILS. The trails androads within the bivouac area may need improve-ment. To avoid excessive tracks within thebivouac, it is desirable to mark routes with whitetape.
c. MINES. In situations where the bivouac areais in territory once held by the enemy, as will usu-ally be the case, the area may have been mined orplanted with booby traps. The pioneer platoonwill locate and remove these mines and boobytraps to make the area safe for the battalion (sec.XIV). If the area is mined extensively the pio-neer platoon will need assistance in this work.When the bivouac area is found to be heavilymined, an alternate area st4ld be selected andused if the situation permits.
21
kZ~~c2~I .-r ~
THREE WAYS TO -I '' 4, INDICATE 'DU DS"-0 -
Figure 9. Improvement of bivouac routes.
22
17. During Occupation
a. GENERAI.. During the actual occupation ofthe bivouac one of the principal duties of the pla-toon will be to assist the CP group and companiesof the battalion in camouflaging and digging in.Where the ground is hard, demolitions may beused for emplacements and other protective meas-ures. The platoon is equipped to do this work,but is limited by the amount of explosives carried.
b. PROTEICTION FOR AREA. To provide protec-tion for the bivouac area, the platoon can beutilized to prepare obstacles along the main ave-nues of approach. Road blocks, mined areas, orother prepared obstacles may be used. Permis-sion from higher headquarters will be obtainedbefore mines are laid or road blocks constructed.Mine fields laid will be marked and reported.The improvement of natural barriers usually ismore effective and involves less work than theconstruction of new obstacles.
C. IMPROVEMENT OF LIVING FACILITIES. Whenthe battalion is in a rest area, or when it appearsthat it may remain in a bivouac area for sometime, the equipment of the pioneer platoon maybe used to improve living facilities. Typical usesare-
(1) Constructing improvised showers.(2) Improving cooking and serving facilities.(3)' Constructing shelter for the maintenance
platoon.(4) Providing dug-in storage for gas and oil
cans.
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CLAYDIGGER INKER
Figur. Poweool
Figure 10. Power tools.
18. Security and Safety in Bivouac
a. SECURITY. The platoon security measures-outposts, dispersion, concealment, camouflage,blackout discipline and noise -discipline-shouldbe automatic. (For bivouac security in generalsee FM 18-5.) If the platoon bivouacs alone it
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establishes outposts for all-round security. Inthose rare instances when the platoon occupies aportion of the perimeter of a bivouac of a higherunit, it will be assigned a security sector and willestablish outposts. The mission of the outpostsis to warn of surprise attack, to stop any attackby enemy troops, and to prevent infiltration intothe area. Outposts maintain liaison, wheneverpossible, with more advanced observation and lis-tening posts established by other units and co-ordinate their fields of fire with those of adjacentunits. An adequate warning system is estab-lished.
b. BLACKOUT PRECAUTIONS Camouflage andnoise discipline and the enforcement of blackoutinstructions are essential. Some common-senseblackout safety precautions are-
(1) Individual vehicles moving within thebivouac in blackout are preceded by a dismountedguide.
(2) Sleeping personnel are checked to see thatnone are near an engine exhaust or in front of orunder a vehicle.
(3) When the platoon moves from bivouac inblackout, men are carefully checked to see thatnone are left behind.
19. Routine Duties in Bivouaca. GENERAL. Besides the specific missions as-
signed to the platoon, there are certain generalduties which will be performed after the bivouachas been 'occupied and organize&fJor defense andsecurity. Primary attention sh7uld be given to
25
the combat readiness of the vehicles, to the fight-ing and working equipment, and to 'the comfortand security of the men. Men take care of theirvehicles and equipment before they take care ofthemselves. The platoon leader and noncom-missoned officers see that vehicles, equipment, andmen are taken care of before they make them-selves comfortable. A check list for the platoonin bivouac is given below. It should be modifiedand amplified as experience warrants.
b. SECURITY.Are the vehicles dispersed and camou-
flaged?Are the machine guns sighted for mutual
support and manned ?Is the air compressor placed in the best
protected location?Have blackout instructions been issued?Have prone shelters or fox holes been
dug?Are sentries posted?Is there relief for men on outposts?Are antitank warning system signals un-
derstood ?Do the men know the challenge, password,
and reply?Are provisions made for proper action in
case .of air attack?c. COMBAT READINESS.
Are the friendly and enemy situationsknown by all?
Is first echelon maintenance being per-formed?
Have all vehicles been refueled?
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Is the air compressor in good operatingcondition ?
Have the tools been checked and foundready for use?
Have the weapons been cleaned andchecked for operations?
Do all vehicles and personnel have basicammunition loads ?
Have all radios been checked?Are reserve rations on hand?Is the platoon ready to move on a mo-
ment's notice?d. CONTACT.
Has contact been established with adjacentunits ?
Has a messenger been sent to the companyCP?
Has the company commander been in-formed of the disposition of the pla-toon?
Do members of the platoon know the lo-cation of the platoon CP? The com-pany CP? The battalion CP? Thebattalion aid station?
Do the members of the platoon know thelocation and general disposition of theother platoons of the company? Dothe key personnel of the platoon knowthe location of the men in bivouac?
e. LIVING IN ANI) LEAVING THE BIVOUAC.
Do the vehicles have firm standing?Have latrine facilities been provided?Have the men the best available shelter?Is water available?
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Have routes of egress been reconnoiteredand suitably marked for night move-ment ?
Is good camouflage discipline maintained?
20. Air attacka. IN BIVOUAC. In the bivouac area all per-
sonnel of the pioneer platoon will dig prone shel-ters or fox holes. When hostile planes are sight-ed, fire will be withheld until it is determined thatthey have located tank destroyer units. Carelessfiring frequently discloses positions that wouldotherwise be unobserved. Enemy planes mayattempt to draw fire for that purpose. If theplanes have located tank destroyer units, fire pow-er of all effective weapons will be used (par. 1 b).
b. MOVING FROM BIVOUAC. Units are particu-larly vulnerable to air attack when moving out ofbivouac. To avoid any possible congestion theplatoon commander coordinates the egress of hisunit with other troops in the .area. All vehiclesmust be dispersed as they move out, not closed inwith the idea of taking distance on the march.
21. Defense against Bivouac Raidsa. PLATOON PLAN. Each platoon should de-
velop and practive a plan to execute in the eventof a surprise raid, especially at night. Regard-less of how far back a bivouac is, a sudden raidby infiltrating or airborne troops is always a pos-sibility, and there may be no friendly troops be-tween the tank destroyers and the enemy. Inmaking defense plans the platoon area should beconsidered as a defense area and the weapons and
28
individual arms of the platoon employed to or-ganize it.
b. ACTION DURING RAIDS. (1) Adequate de-fensive action during a night raid requires thor-ough training and rigid discipline. Each unitshould adopt a standing operating procedure fordefense at night. One method is to prescribe twoalert signals, as follows:
(a) First 'signal is sounded when an enemy at-tack or infiltration appears imminent. All per-sonnel occupy prepared positions with 50 percenton alert and others resting.
(b) Second signal is sounded when an enemyattack or infiltration is made. All personnel arealerted and remain in prepared positions. Allmovement within the area is assumed to be hostileand subject to immediate attack.
(2) The primary weapons for defense against'close-in night 'attacks are antitank and antiper-sonnel mines, flares, grenades, bayonets andknives. The firing of weapons is rigidly con-trolled as their flash discloses the location of thefirer. There is no withdrawal from a positionduring a night attack. All men must understandthat they are "frozen" to their positions regard-less of what happens.
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Section V
POSITION IN READINESS
22. GeneralA position in readiness is an area which an or-ganization occupies while the battle situation isdeveloping. There will, in all probability, be sev-eral possible combat areas in which the actionmight take place. During the period of waitingfor developments the pioneer platoon is preparedto move rapidly to execute any missions assigned.
23. Reconnaissance of Combat AreaWhile the position in readiness is occupied, pis-sible combat areas are reconnoitered. Usuallythe pioneer platoon commander and the two sec-tion sergeants go forward, one with each guncompany commander, to estimate the extent ofwork required in missions which they may becalled upon to execute within the different areas.
24. Occupation and DutiesDispositions of troops and vehicles in a positionin readiness are similar to those in bivouac (sec.IV). While the battalion occupies the positionin readiness the pioneer platoon executes the mis-sions assigned after the reconnaissance of thecombat area. Principal missions at this time areto see that routes to the selected combat areas arefree from obstacles, both natural and man-made(FM 5-30). When time permits, the platoonmay assist in improving gun positions. The mis-sions of the platoon may be numerous: thereforethe battalion plan of action determines the prior-ity of such tasks.
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Section VI
COMBAT AREA
25. Obstaclesa. REMOVAL OF OBSTACLIES. It is a function of
the pioneer platoon to remove or assist in remov-ing obstacles, both natural and artificial, includingmine fields and booby traps (FM 5-30).
b. CONSTRUCTION OF OBSTACLES. When timepermits the deliberate occupation of positions, allpossible means of forcing the enemy to fight onground chosen by the tank destroyers should beused. The pioneer platoon will often be directedto move forward to execute demolitions, laymines, build road blocks, and construct other ob-stacles with which to canalize the movement ofthe enemy (FM 5-30). In selecting gun posi-tions there may be approaches which cannot becovered by fire from the destroyers. Obstacleswill be constructed to deny the enemy the use ofsuch approaches. The pioneer platoon may berequired to assist the security sections of the gunplatoons in covering these obstacles by fire.
26. Preparation of Gun PositionsFrequently the pioneer platoon will be employedto assist gun crews in preparing gun positions.The equipment and training of the personneladapt them to jobs such as assisting in digginggun positions, preparing" camouflage, clearingfields of fire, and improving routes into and outof position. The platoon also may be employed
31
S. 'p
r.:~~~~~~~~'l
..Al,
F7~~~~~~~~~~L,~~~~~~
C-
Figure 11. Preparation of a gun emplamen ent.
32
to assist in the preparation of alternate and dum-my gun positions. To add realism to dummypositions the platoon may equip them with ex-plosive charges called fougasses (par. 53).
27. Fire FightDuring the fire fight the pioneer platoon reor-ganizes, if necessary, and assists in the defense ofthe command post. It will be prepared at alltimes to move forward and perform new missions.
28. Retrograde MovementsDuring a retrograde movement the pioneer pla-toon is generally assigned to the rear guard toassist in delaying the enemy. The platoon pre-pares road blocks, increases the effectiveness ofnatural obstacles, lays hasty mine fields, and pre-pares bridges and defiles for demolition as di-rected by the rear guard commander. In turn,the rear guard covers the obstacles with fire whilethe pioneer platoon moves on to the next task inthe movement. Authority from the rear guardcommander, who in turn will have obtained per-mission from division or higher commander, mustbe obtained before laying mine fields, installingbooby traps, or executing demolitions.
33
ENEMY
+ + 4.+ ++
+ 4
... >,/ \-/--- ----
(PREPARED FOR -- F
'4 i ...
+t + + I X )
Figure 12. Actionl witl/ rear guard during retrogradenmovements.
34
Section VII
TECHNICAL TRAINING
29. MissionFrom the previous discussion of the two generalmissions it will be noted that the tasks of the pio-neer platoon are similar to those of a platoon ofcombat engineers. The technical training of theplatoon must therefore be similar to that of en-gineers. The personnel should be trained thor-oughly in the technique of constructing andremoving obstacles and in at least the elementaryengineering tasks commonly assigned to theplatoon.
30. Referencesa. In addition to the techniques described in this
manual, the personnel .of the pioneer platoonshould be trained in all the techniques given inFM 5-10, Construction and Routes of Communi-cations, FM 5-30, Obstacle Technique, FM 5-31,Land Mines and Booby Traps, and in the follow-ing subjects in FM 21-105, Engineer Soldiers'Handbook:
Engineer tools and common engineertasks.
Elementary rigging.Camouflage.Explosives and demolitions.Bridges.Engineer reconnaissance.Combat weapons.
35
b. In using FM 5-10, FM 5-30, FM 5-31,FM 21-105, and other manuals referred to inthis text, the subject material must be adapted tothe organization and equipment of the platoon.
Figure 13. Technical references for the pioneer platoon.
36
Section VIII
SAFE STRENGTH OF EQUIPMENT
31. GeneralAs members of the pioneer platoon will frequent-ly be working with ropes, chains, winches, andlike equipment, they must know the safe workingstrength of this equipment. Should the equip-ment break while being used, personnel may beinjured and the mission may not be performed.To satisfactorily complete a mission with the leastdanger to personnel, the load should always bekept within the safe working strength of theequipment being used.
32. Rope, Wire, and Chain (FM 5-10).The following simple rules are applied to deter-mine the safe working load of rope, wire rope,and chain:
a. ROPE. Working strength (in tons) equalsthe diameter (in inches) squared (T = D2 ).
Example: The safe working strength of a 52
inch rope is Y4 ton-T (tons) = D2 (diameter in inches
squared)T = ½2 X Y2 = 54 ton.
b. WIRE ROPE. Working strength (in tons)equals eight times the diameter (in inches)squared (T = 8D2).
Example: The safe working strength of a 5
inch wire rope is 2 tons-T (tons) = 8D2 (diameter in inches
squared).T = 8 >3/ 2 > X 2 = 2 tons.
37
c. CHAIN. Working strength (in tons) equalseight times the diameter (in inches) squared(T = 8D2). (Measure the thinnest portion ofa link of chain to find the diameter.)
Example: The safe working strength of a 52
inch chain is 2 tons-T (tons) = 8D' (8 X diameter in
inches squared)T = 8 X ¼ X 25 = 2 tons.
33. Winchesa. CAPACITY. The table below shows the ca-
pacities -of winches used by the battalion. Thesecapacities must not be exceeded. When there isdanger of exceeding the capacity of the winch, theload can be lessened by using blocks (see FM21-105).
Weight of vehicle Winch capacity, lbs.5 ton and /4 ton ................... 5,00012 ton and 2X2 tons .............. 10,0004 tons and larger...................... 15,000
b. SHEAR PINS. To protect against overload,the propeller shaft universal joint is fastened tothe worm shaft of the winch by a shearpin whichwill break if the winch is overloaded. The shearpin is installed as a safety measure; only the speci-fied pin should be used for replacement. If thepin will not stand the strain, reduce the load onthe winch.
c. OPERATION. The winch has two forwardspeeds and one reverse speed. The lower speedshould be used for heavy loads. The winchmust be operated with a constant tension on theline, as the winch will not withstand a suddensnap or strain.
38
Section IX
ROAD EXPEDIENTS
34. GeneralThe pioneer platoon ordinarily is not called uponto make permanent road repairs, but is expectedto employ expedient methods for hasty road re-pairs and construction. The type of road builtdepends on the time available and the usable ma-terials near the road site. (FM 5-10 presentsadditional road expedients.)
35. Corduroy Roadsa. USAGE. The corduroy road is one of the
most reliable and widely used expedient roads.It may be constructed easily and rapidly whentimber is conveniently available. The platoonmay construct corduroy roads to improve soft ap-proaches to fords and bridges and to negotiatemud holes and short stretches of swampy ground.
b. CONSTRUCTION. The corduroy road is builtby laying logs, split or round, crosswise to the axisof the road. The logs should have a mean diam-eter of 6 inches, be as nearly the same size as pos-sible, and be laid by alternating tips and butts. Ifthe logs are large, the spaces may be filled withsmaller poles. These poles should be trimmed tofill the gaps closely. To make the road smootherfor traveling, the entire structure may be coveredwith a layer of hay or same similar material which
39
THE METHOD OF PLACINGLONGITUDINAL STRINGERS
OER
Figure 14. Corduroy roads.
40
is then covered with a layer of dirt. If the soil isreasonably solid, the logs need be only as wide asthe width of the road; on marshy ground, the logsmust be wider than the road.
C. CURBING. Logs should be used as curbingon corduroy roads. This log curbing is spiked,wired, and staked in place on the upper surfaceand outer edges of this type road. The curbinghelps to bind the logs of the road together and tokeep the road itself in place. Curbing is also use-ful in keeping in place any hay, dirt, etc., that isused -to cover the roads. Whether the road iscovered or not the curbing serves to prevent ve-hicles from slipping off the road.
36. Wire Mesh Roads
a. CONSTRUCTION. When deep, dry sand is tobe crossed and no material for a corduroy road isavailable, a chicken-wire, hog-wire, or otherheavy-wire mesh road may be constructed. Ordi-nary 3-foot rolls of wire may be used and sev-eral widths wired together with a one-foot over-lap to construct the desired width of road. Theentire mesh should then be solidly anchored. Asingle thickness may be sufficient for light vehicles;however, three thicknesses, with burlap or brushbetween layers, are required for cargo and otherheavy vehicles. Such meshroads may be coveredwith dirt.
b. MAINTENANCE. Constant maintenance isnecessary to repair holes in wire and to keep thewire taut with the surface of the sand. Traffic
41
should never be allowed to cross a wire-mesh roadat right angles. If such traffic is necessary, ap-propriate plank or other type of crossing shouldbe made.
TREADS OF BURLAP OR OTHERMATERIAL BETWEEN LAYERS
OF WIRE MESH.
ONE LAYER OF LAPPED WIRE MESHTO MAKE REQUIRED ROAD WIDTH
NOTE- DRAWINGS SHOW WIRE MESH IN 6' WIDTHS
Figure 15. Wire-niesh roads.
37. Tread RoadsShort sections of this type of road may be con-structed when time and materials are limited. Itis otherwise less desirable than other types. Spac-ing of cross ties is generally 3 feet but may varywith subgrade conditions. Inside curbs are nec-essary to prevent vehicles of various width treadsfrom driving off road.
42
STANDARD LUMBER
IMPROVISED LUMBER
CORDUROY
Figure 16. Types of tread roads.
43
Section X
STREAM CROSSING EXPEDIENTS
38. Fordsa. GENERAL. If a bridge is not available, ford-
ing a stream is ordinarily the quickest and easiestway to cross it. Even though there may be abridge, a ford should be located in the event thebridge is rendered unserviceable by enemy action.If the selected ford site needs improvements, thepioneer platoon will be called on to do the workif the job is not too extensive.
b. FORDABILITY OF VEHICLES. The depth ofwater that normally can be forded by the vehiclesof the battalion is shown in the table below:
NormalVehicle fordability
in inches
Truck, / -ton .................................... 18Truck, Y4-ton, weapons carrier and com-
mand ..................................-....... ...... 34Truck, 12½-ton, 6 x 6, cargo, w/winch.... 34Truck, 2½2-ton, cargo, w/winch ............... 36Compressor, air, motorized...................... 36Truck, heavy wrecker, w/winch .............. 40Car, armored, light, MS.........-------------.... 34Car, armored, utility, M20 ....................... 34Vehicle, tank, recovery .......................... 36Carrier, personnel, half-track M3..-......... 32Carriage, motor, 76-mm gun ................... 48Carriage, motor, 3-inch gun ...................... 36
44
C. IMPROVING APPROACHES. To maintain traf-fic flow, the approach to and the exit from theford, whenever possible, should be perpendicularto the stream for at least fifty yards. The ap-proaches must be firm enough to support the ve-hicles of the battaion and have a slope gradual
m'~ ~ ~ ~ ~ ~ ~ ~ ~~ l CHI CKEN. HOG OR
Figure 17. Ford improvements.
45
enough for the vehicles to enter and exit easily.Soft approaches may be improved by the construc-tion of corduroy roads or other road expedients.Steep approaches may be cut down either by handlabor or by the use of explosives.
d. IMPROVING STREAM BED. If the stream bedis not firm enough to support the vehicles, it maybe improved by constructing a semi-floating cordu-roy road with the logs wired together and an-chored at each end to keep the current fromshifting the road. The stream bed may also beimproved by placing sand bags or heavy-wire meshto form a roadway. On a dry sand bar a chicken-wire or hog-wire road may be constructed.
39. FloatingWhen suitable fords cannot be found or where thewater is too deep to be forded by the smaller ve-hicles, these vehicles may be floated across thestream. One method is by the use of tarpaulinsof large vehicles to float the smaller vehicles.The tarpaulin from a 252-ton truck is largeenough to provide a float for a j4-ton truck.
Figure 18. Floating a vehicle.
46
Figure 19. Types of rafts.
47
40. RaftsThe lighter vehicles may also be transported onrafts constructed from oil drums, logs, or boats.Rafts made from vehicle tarpaulins on a frame-work of saplings, boards, or truck bows can beused to transport men and light equipment.
41. Cable FerryWhen the banks are steep, the water too deep forfording, or the current too swift for floating, per-sonnel and light equipment can be ferried by usingthe winch cable of a vehicle. Heavier equipmentup to a '4-ton truck can be ferried by using two25--ton truck winch cables (ch. 11, sec. IV, FM5-10).
48
- -t~v-,,r--t.~yr7
<~~~~~~~~ 2 ;t1 TygONE WI NCH DN 4t
-~~~~n _s O""""l
FERRSYING SOLDIERSAND LIGHT EQUIPMENT -
a/ DTRIPODS TOGIVE ADODITIONAL.
HEIGHTH
rERYVIN
19i~~~~~~~~~~~~~~~~~~~~~/
/ I/adTON
Figure 20. Cable ferry.
49
Section XI
BRIDGE STRENGTHENING
42. Nomenclature of Military BridgesBridges may be encountered which are not strongenough to support the vehicles of the battalion,but which may be strengthened sufficiently.Sometimes it may be necessary to erect entiresmall bridges. In order to estimate the capacityof a bridge and the work necessary, and to do thework efficiently, all personnel of the platoon mustbe thoroughly familiar with the nomenclature ofthe standard military bridge. The diagramsshown in figures 21 and 22 should be studied care-fully. It should be noted that 10 feet betweencurbing is insufficient for some military vehicles.The maximum capacity of bridge type shown infigures 21 and 22 is 24 tons when span length isat its maximum of 15 feet.
43. Addition of Bentsa. G-Ns }RAL. Ordinarily, the best method of
strengthening the span of a bridge is to insert ad-ditional supports in the center of the span. Thestandard trestle bent is the easiest and quickestsupport to build and will approximately doublethe strength of the span. \\here the ground un-der the bridge is uneven, the posts may be cut tosuit the terrain and a common cap may be used ontop of the posts. If this is done a separate foot-ing is usually required under each post.
50
SCABBIN G 3 .'
,'FoELs- FOOTERS
Figure 21. Cross section of bridge.
b. WEDGING ADDITIONAL BENTS. If the stand-ard trestle bent is used for an additional support,wedges may be used to eliminate the excessiveamount of time needed to construct a bent of theexact height necessary. The posts should be cutfrom 3 inches to 4 inches shorter than necessaryand a double wedge driven between the cap andeach stringer so the load will be transferred fromthe stringers to the bent. Constant mainte-
51
SIDE VIEW
ABUTMENT SILL HORIZONTALFOR GREATER BEMR-
ING SURFACE.
CONSTRUCTIONDETAILS
:-4 ~"~.~ SILL CENTERED
- ~ ~ ~ ~ ~ ~ - FOOTER>12 X Y'-00
SBLCKSN\\ ABUTMENT, END DAMRL OCK9& an REMOVED
K BAGUITMENT 9Ig 6" ABUTMENT FOOTINGSILL glr X 12- X 3'-0
Figure 22. Side view and construction details.
52
KNEE-
Figure 23. Hdition and bracing of bents.L
Figure 23. Addition and bracing of bent.
153
nance of these wedges will be required to keepthem bearing against the cap and stringers. Aribbon board (figure 23) may be nailed across thestringers to keep the wedges in place.
c. KNEEi BRACING. Knee bracing can be usedto add rigidity to the bridge. There should beone brace on each post of the bent.
44. Construction of A-framea. In places where the water is too deep for
bents, the A-frame may be used to strengthen aspan. A-frames are more difficult to constructthan standard bents; however, the following dis-cussion presents a simple method of constructionthat can be used by the pioneer platoon.
b. The easiest way to lay out the length andangles of an A-frame is by the use of a steelsquare. To do this, the length of the span frompost to post (L) must be known, and the heightof the span from the sill to the stringer (H).Four inches are subtracted from the height (H),giving the dimensions (H-4 inch). The 4 inchesthus subtracted, together with the 4 inches thatwill be cut from the apex of the assembledA-frame to provide a flat seat for the cap (figure26), allows 8 inches for the 6-x-8-inch cap to beplaced between the A-frame and the stringers.
c. As any two bents may be of different heights,it may be necessary to lay out each leg of theA-frame separately. The first step in laying outa leg is to place the steel square on the end of thetimber which is to be the bottom of the leg, letting
54
E4AME IN
Figure 24. Conlpleted A-fralme with known dimensions.
55
one inch on the scale equal one foot on the timber.With L/2 on the right scale and H-4 inch on theleft scale, the line AC is drawn and point B mark-ed as shown in figure 25.
d.j The distance 4B is measured. Then, let-ting each inch on the scale equal one foot 'on thetimber, the length AD is laid out so that AD ihfeet is equal to AB in inches. This will give thelength of the A-frame leg as shown in figure 25.
e. To lay out the point of the A-frame leg, thesteel square is placed on the opposite end of thetimber so that the left scale touches point D atH-4 inch and L/2 still intersects line AD. Theline DE is drawn as shown in figure 25.
f. The timber is cut along AC for the bottomof the A-frame leg, and along DE for the top ofthe leg. Four inches are cut from the point ofthe A-frame to allow room for an 8-inch cap tofit between the top of the A-frame and the string-ers.
g. In finding the dimensions for the leftA-frame leg, it should be noted that L/2 equals7 feet on the bridge and 7 inches on the square,and H-4 inch equals 10 feet on the bridge and 10inches on the square. By properly placing thesquare -on the timber it is found that the distancefrom point A to point B is 12.2 inches; therefore,the distance between point A and point D is 12.2feet. The same procedure is followed to lay outthe right A-frame leg except that measurementsmust betaken to find the new value of 11-4 inchsince the right bent is shorter than the left bent.
56
Figure 25. Laying out leg of A-frame.
57
I
E" rAELCWt
11~~~~~~~~~~~1
I
II
Figure 26. Cutting A-frame leg.
58
(V
I
Figure 27. A-frame with uneven legs.
45. Addition of StringersBridges may be strengthened by the use of addi-tional stringers. These may be added either byjacking up the floor and inserting a stringer, or byhewing approximately one inch from the underside of a new stringer for a distance of two feetfrom'the end, fitting the stringer into place paral-leling the old stringer, and blocking it up withdouble wedges placed between the cap and thestringer after the latter is in position. If neces-
59
sary, all the flooring may be removed to expeditethe placing of extra stringers.
46. Replacing PostsIt may be possible to repair broken posts by nail-ing scabs over the breaks. If a broken post can-not be repaired, another post is cut and slid intoplace beside the broken one. To cut and place anew post that exactly fits is a tedious job. Theposts should, therefore, be cut slightly shorterthan the required elength and tightened in placewith wedges.
47. Other Strengthening MethodsThe impact load of a bridge can be reduced andthe capacity of the span increased by smoothingthe flooring. Loose boards are nailed down andrough spots chipped off. All broken planks arereplaced. The addition of a tread will distributethe load on the flooring more evenly and increasethe bridge capacity. If the material is availableand if the bents are in good condition, a new setof stringers and a new floor can be laid directlyover the old floor.
60
eLACINGTREADVERFLOORING
ADDITIONALPOSIWEDGED IN PLACE
SCABBINGOVER BREAK
ADDITIONAL STRINGERWITH DOUBLE WEDGES
Figure 28. Other methods of strengthening bridges.
61
Section XII
DETERMINING CAPACITY OF BRIDGES
48. Weight of Vehiclesa. GENERAL. To be able to determine whether
or not a bridge will support the vehicles of thebattalion and the amount and kind of repairsneeded to strengthen the bridge, members of thepioneer platoon must be thoroughly familiar withthe weights and types of the various vehicles ofthe battalion.
b. NORMAL WEIGHTS. The following tablegives the gross weights of the battalion vehicleswith a normal load. A system of using the equiv-alent weight of vehicles for various span lengthsof stringer-type bridges (FM 5-10) may be usedto determine passability of vehicles across bridgeshaving load capacity posted.
Gross weightVehicle with normal
loadTruck, %2-ton .. 3....................... 3,125Truck, Y4-ton, weapons carrier or com-
mand ...................................... 6,800Truck, 1 2-ton, 6 x 6, cargo, w/winch._ 10,225Truck, 23/-ton, cargo, w/winch.......... 15,000Compressor, air, motorized ................. 13,000Truck, heavy wrecker, w/winch .......... 37,000Vehicle, tank, recovery.....-................... 70,000Car, armored, light, MS8 ...................... 16,000Car, armored, utility, M20 ................. 15,500Carriage, motor, 90-mm gun, M36 ...... 63,500
62
Carriage, motor, 76-mm gun --.............. 38,500Carriage, motor, 3-inch gun.................. 64,000Carrier, personnel, half-track, M3...... 19,000Trailer, ¼4-ton ................................... 1,060Trailer, i-ton ................................... 3,300Trailer, ammunition, M10.................. 4,000Gun, 3-inch, MS and carriage, gun
3-inch, Ml-------------------------------..................................... 5,100Gun, 3-inch, MS and carriage, gun
3-inch, M6 ....--.....-...-...--...------------- 5,900c. PASSAGE WITH CAUTION. It should be re-
membered that when the weight of a vehicle isnear the capacity of the bridge, extreme cautionmust be used in crossing. Ordinarily a bridgewill carry a 25 percent overload if the followingprecautions are taken: Vehicle must stay on cen-ter line of bridge. Speed not over 5 miles perhour. Distance between vehicles, at least 50yards. No braking or gear shifting on bridge.While the 25 percent overload does not apply tofloating bridges, passage with caution means thesame as on fixed bridges except that speed mustbe reduced to 3 miles per hour.
49. Bridge Cardsa. GENERAL. A rapid means of determining
the capacity of bridges and the amount of repairsneeded is by the use of bridge cards. Each pio-neer platoon leader and at least the members ofthe platoon who will be sent on the reconnais-sance missions should have copies of the bridgecards that apply to the vehicles of the battalion.The use of these cards should be practiced so allmembers of the platoon can use them rapidly and
63
accurately. Structures must be examined forsoundness -of timber and steel deterioration andappropriate reductions in capacity made accord-ingly. For special cases involving towed loadssee paragraph 50.
b. BRIDGES OF MORE THAN ONE LANE. (1)General rule. The bridge cards present a methodof determining the capacity of a span of one laneonly. To find the capacity of each lane of a two-lane span, count the stringers under each lane andsolve for each lane separately. Thus, the spanmay be found to have a capacity of two 10-tonvehicles (one in each lane), but this does not meanit will carry one 20-ton vehicle.
(2) Emergency passage. In an emergency thecapacity of a two-lane bridge may be exceeded byobserving the following procedure-count thestringers in both lanes of the span and multiplythis number by Y4 ; then, using this result as a totalnumber of stringers in a span of a I-lane bridge,find the capacity of the span. When this methodis used only one vehicle should be on any one spanat one time, and it must be driven along the centerline of the bridge.
C. WHEELED VEHICLES AND HALF-TRACKS.Half-tracked vehicles can safely cross all bridgescapable of carrying wheeled vehicles of the sameweight. The following bridge cards may be usedto determine the weight of wheeled vehicles orhalf-tracks which a one-lane bridge will support.
(1) Rectangular wooden stringers with. timberflooring. The card below shows the safe grossload in tons for stringers one inch wide.
64
Depth of Stringer in Inches
6 8 10 12 14 16 18 20 22 24
10 .191 .341 .551 .801 1.0511 .401.75 2.15j 2.6513.1512 .151 .281 .441 .651 .9011.1511.4511.8012.1512.60
14 .131 .241 .371 .551 .751 .9511.2511.5511.851 2.20. 15 .21 221 .351 .501 .701 .9011.151 1.401 1.7012.05
16 .111 .201 .321 .47 .651 .851l 1.0511.3011.601.90a18 .101 .181 .281 .411 .55 .751 .9 1.151 1.4011.70
20 16! .251 .361 .501 .651 .8511.051 .25 1150
24 II .09 .191 .271 .382 .501 .651 '651 .911.1528 .091 .151 .221 .321 .421 .551 .651 .o01 .95
Figure 29. Wheeled vehicle bridge card (woodenstringers).
Example: To determine the capacity of a l-lanebridge which has six 8-x-xlO-inch wooden stringersover a span of 18 feet.
Solution: The column for the depth of stringersof 10 inches is intersected by the line for a span of18 feet. The figure .28 appears in the block atthe junction of the two columns. This (.28) isthe number of tons one 1-inch stringer would sup-port. The actual stringer width of the bridge is6 (number of stringers) X 8 inches (width of eachstringer) or 48 inches. The safe capacity of thebridge is therefore .28 (capacity for a width of1-inch) X 48 (total width) equals 13.4 or 13tons.
Round stringers. For stringers of round timber,the diameter of the tiwber at the center of the
65
span is used as the depth, 0.4 of the diameter asthe width, and the above bridge card is applied.
(2) Steel stringers (standard I-beams) withtimber flooring. The card below shows the safegross load in tons for one steel stringer.
Depth of Stringer in Inches6 7 8 10 12 15 18 20 24
10 2.61 3.81 5.01 9.01 13.01 21.5132.5143.01 64.5
12 2.21 3.11 4.31 7.5111.0118.01 27.01 35.51 53.0
14 1.81 2.61 3.61 6.01 9.01 15.0122.5130.0) 45.0
15 1.71 2.41 3.31 s.81 8.5114.0121.0128.01 42.0
116 1.6 2.31 3.11 5.51 8.0113.01 20.0 26.0) 39.018 1.41 2.01 2.71 4.71 7.0 11.5 17.5123.01 34.5
e 20 1.21 1.8) 2.41 4.21 6.0110.5115.5120.51 30.5
24 ) 1.31 1.81 3.21 4.81 8.0112.0115.51 23.5
28 I1.11 1.51 2.61 4.01 6.51,0.0113.0119.5
32 [I 1.21 z2.01 3.11 5.01 8.0110.5) 15.5
36 | I I 1.81 2.71 4.51 6.51 9.0 13.5
40 I) I |1 2.31 3.91 6.01 12.
Figure 30. Wheeled vehicle bridge card (steel stringers).
Example: To determine the capacity of a l-lanebridge which has six 10-inch standard I-beamstringers over a span of 20 feet.
Solution: At the intersection of the column forthe depth of stringers of 10 inches and the columnfor a span of 20 feet, is found the figure 4.2which is the capacity of one stringer. The actual
66
number of stringers is 6; therefore, the safe ca-pacity of the bridge is 6 X 4.2 equals 25.2 or 25tons.
Railroad rails. Standard railroad rails shouldbe considered as 6-inch I-beams.
d. DATA USED FOR COMPUTING WHEELED VE-HICLE BRIDGE CARDS. Safe unit bending stresses-2,100 p.s.i. for wood, 24,000 p.s.i. for steel.(For -other data see FM 5-10.)
e. 3-INCIH GUN MOTOR CARRIAGE. The fol-lowing bridge cards may be used to determine thestringer requirements to carry the 3-inch gun mo-tor carriage, M10, (weight 64,000 pounds) on a1-lane bridge. They may also be used for thetank recovery vehicle.
(1) Rectangular wooden stringers with timberflooring. The card below shows the total stringer
Depth of Stringer in Inches
6 8 10 12 14 16 18 20 22 24
10 911 $21 331 231 171 131 101 81 7
12 132741 481 331 241 19! 15| 12 10114 1 81 631 441 321 251 201 161 13 11
1r 1131 721 501 371 281 221 181 151 13'16 1 1261 801 561 411 311 251 201 171 14
18 971 681 501 381 30 241 201 .170 1 1151 801 591 431 351 291 241 20
22 I 1 1321 921 681 521 411 331 23
24 I 1 041 761 s81 46 37j 31
Figure 31. Bridge card (wooden stringers). 3-inch gunnmotor carriage.
67
width in inches required to carry the 3-inch gunmotor carriage, or the tank recovery vehicle.
Example: A 1-lane bridge has six 6-x-12-inchwooden stringers over a span of 14 feet. Will itcarry the 3-inch gun motor carriage?
Solution: At the intersection of the column forthe depth of stringers of 12 inches and the columnfor a span of 14 feet is found the figure 44 whichis the total stringer width in inches required.The actual stringer width is 6 (number of string-ers) X 6 inches (width of each stringer) equals36 inches total width. Therefore, the bridge willnot carry the vehicle. (To strengthen the bridge,two stringers are added or the span is shortenedby adding a trestle bent or A-frame.)
Round stringers. For stringers of round timber,the diameter of the timber at the center of thespan is considered as the depth, 0.4 of the diame-ter as the width, and the above card is applied.
(2) Steel stringers (standard I-beam) withtimber flooring. The card below shows the totalnumber of steel stringers required to carry the3-inch gun motor carriages, or.the tank recoveryvehicle.
Example: A l-lane bridge has six 10-inchI-beam stringers over a span of 20 feet. Will itsupport the 3-inch gun motor carriage?
Solution: At the intersection of the column forthe depth -of stringers of 10 inches and the columnfor a span of 20 feet, is found the figure 7 whichis the number of stringers required. The actualnumber of stringers is 6; therefore the bridge willnot carry the vehicle. (To strengthen the bridge,
68
Depth of Stringer in Inches6 8 10 12 14 16 18 20 24
10 5| 31 21 21 1 1 I12 81 41 31 21 21 1 1 114 101 61 41 31 21 21 I15 111 71 41 31 21 21 1 I
e16 131 71 51 31 31 21 211 S 1 61 41 31 21o20 191 101 71 51 41 31 2124 1 141 9 61 61 51 41 31 21 228 I 171 11I 8 6 1 4 31 31 232 1 201 131 91 71 51 4 31 236 | 1 I51 101 81 61 51 41 340 I 1171 121 91 71 451
Figure 32. Bridge card (steel stringers). 3-inch gunmotor carriage.
one stringer is added or the span is shortened byadding a trestle bent or A-frame.)
Railroad rails. Standard railroad rails are con-sidered as 6-inch I-beams.
f. 76-MM GUN MOTOR CARRIAGE. The fol-lowing bridge cards may be used to determine thestringer requirements to carry the 76-mm gun mo-tor carriage (weight 38,500 pounds) on a l-lanebridge.
(1) Rectangular wooden stringers with timberflooring. The card below shows the total stringer
69
width in inches required to carry the 76-mm gunmotor carriage.
Depth of Stringer in Inches
6 8 10 12 14 16 18 20 22 24
10 661 371 241 171 12 91 71 61 S 412 941 31 341 231 171 131 101 91 71 6141231 701 451 311 231 171 141 11l 91 815 1 771 s 341 251 191 151 121 101 9
'16 1 861 55 381 281 2aj 171 141 11 l0o8oj 1001 651 451 331 251 201 161 131 11
20 1201 771 531 39 301 241 191 161 1322 | I 881 611 451 331 271 221 181 1524 I 991 681501 s 38 301 251 201 17
Figure 33. Bridge card (wooden stringers.) 76-mm gunmotor carriage.
Example: A l-lane bridge has six 6-x-12-inchwooden stringers over a span of 16 feet. Willit carry the 76-mm gun motor carriage ?
Solution: At the intersection of the column forthe depth of stringers of 12 inches and the columnfor a span of 16 feet the figure 38 is found, whichis the total stringer width required. The actualstringer width is 6 (number of stringers) X 6inches (width of each stringer) or 36 inches.The actual stringer width is less than that requir-ed, so the bridge will not carry the vehicle.
Round stringers. For stringers of round tim-ber, the diameter of the timber at the center ofthe span is considered as the depth, 0.4 of thediameter as the width, and the above card is ap-plied.
70
(2)Steel stringers (standard I-beam) withtimber flooring. The card below shows the totalnumber of steel stringers required to carry the76-mm gun motor carriage.
Depth of Stringer in Inches6 8 10 12 14 16 18 20 24
10 41 2j 21 1 I I I12 61 31 21 21 I I I I14 71 41 31 21 1 I I I15 81 51 31 21 21 1 I 1,,16 I 9 5I 31 21 21 I I1is 11 61 41 31 21 2 1 I
120 121 71 51s 31 21 21n 24 16 91 61 41 31 2 21 2
28 201 111 71 51 41 31 21 2132 231 131 91 61 51 31 31 2 236 1 151 101 71 51 41 31 31 240 1 171 II 81 61 51 41 31 2
Figure 34. Bridge card (steel stringers). 76 -mnm gunnmotor carriage.
Example: A l-lane bridge has six 10-inchI-beam stringers over a span of 24 feet. Will itcarry the 76-mm gun motor carriage?
Solution: At the intersection of the column forthe depth of stringers of 10 inches and the columnfor a span of 24 feet, the figure 6 is found, whichis the number of stringers required. The actualnumber of stringers is 6; therefore, the bridgewill carry the vehicle.
71
Railroad rails. Standard railroad rails are con-sidered as 6-inch I-beams.
g. DATA USED FOR COMPUTING 3-INCH AND76-MN GUN MOTOR CARRIAGE BRIDGE CARDS.Safe unit bending stresses-2,100 p.s.i for wood,24,000 p.s.i. for steel; stringer efficiency 80 per-cent; impact 25 percent; dead load of 220 poundsper foot (weight of stringers neglected).
50. Towed Loadsa. GENERAL. In calculating the ability of a
bridge to carry a towed load, two factors must beconsidered:
(1) The weight of each part of the load, thatis, the weight of the towing vehicle and of thetowed vehicle.
(2) The length of the two parts of the loadin relation to the length of the span of the bridge.
b. SHORT SPANS. If the span of the bridge isshort enough so that only one part of the load isover the span at one time, each part of the loadmay be considered as -a separate vehicle.
c. LONG SPANS. When the span of the bridgeis long enough so that both parts of the load willbe on it at the same time, two rules apply:
(1) Vehicles loaded to rated capacity. Thetotal weight consists of the weight of the heaviervehicle plus one-half the weight of the lighter ve-hicle. This principle applies because the twoparts of the load will not be on the same spot atthe same time.
(2) Vehicles overloaded. The combinedweight of both vehicles should be considered asthe load on the span.
72
Section XIII
DECEPTIVE MEASURES
51. Generala. Deceptive measures are frequently used in
combat to mislead the enemy and to cause him todissipate his fire. For example: chains, brush, orother improvised drags may be pulled behind ve-hicles to create a dust cloud resembling the move-mcnt of a large column. Bivouac areas may besimulated by creating tracks and signs of activitynormally associated with such areas. Dummyinstallations and decoy positions may be con-structed.
b. In the employment of deceptive measures itmust be remembered that the enemy is smart.The positions must be logical, they must be con-stantly maintained, and the construction shouldbe simple. The success of the work will dependon the resourcefulness and ingenuity of the menand their ability to use the materials available.
52. Dummy Gun PositionsOne of the most effective deceptive measures isthe dummy gun position. To construct such aposition a log may be used to simulate the tubeof a gun. The tracks, blast marks, and othersigns of activity characteristic of a gun positionshould be created. The dummy should be placedin a logical firing position and should be partiallyconcealed, leaving only those tracks and signs ofactivity'which usually disclose position. It must
73
_ - ,~~~~~~~C
'^o
C
V
A n~~~~~~~~'A
I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I
I~~~~~~~~~~
be remembered that it is not the indivdual decoybut the activity and characteristics of an actualposition that will deceive the enemy.
53. FougasseDummy gun positions may be made more realisticby simulating muzzle blast through the use of afougasse. A fougasse that creates a fake muzzleblast similar to that of a 3-inch gun may be con-structed by the use of two pounds of TNT togive a sound and flash similar to the gun firingand an additional 5 pound of TNT to blow dustout of a hole in the ground to give the effect ofthe muzzle blast. A fougasse is most effectiveif it is located in a logical gun position and shouldbe fired while actual guns are firing.
Figure 36. Dummy gun.
75
UMY GUN POSITION(PARTIALLYCONCEAILO)
BLASIT M BAI S
5 rEcii-t
I'
I I ft hbl
DUMMYGtUN WITH rOIJG1\sE.SIMULATING MUZZLE BLAST.
Figure 37. Dummy gun positions and fougassers.
76
Section XIV
MINE REMOVAL
54. Organizationa. When mines are encountered the pioneer
platoon usually will be charged with breachingmine fields or removing scattered mines. How-ever, it must be prepared to lift entire mine fields.These operations must be done rapidly and alwayswith great care or excessive casualties will result.Therefore, all personnel must be organized andthoroughly trained and drilled in mine removal tofurther the rapid movement of the battalion.
b. The basic principles of mine field removalorganization are contained in FM 5-31. Thepioneer platoon, however, does not have as largean organization as is shown. Figures 38 and 39outline an organization which is readily adaptedfor use by the pioneer platoon.
c. The breaching party is organized as follows:Officer NCO Men
Advance party .-... --..... ............. 1 1 2No. 1 party-taping ..........-..... .. 1 6No. 2 party-detecting - -........ . 1 8No. 3 party-detecting ...-....... . 1 8No. 4 party-reserve & supply . 1 4
1 5 28Parly duties. (1) The advanr;party indicates
to the taping party the locationiof the startingtape and lays out the direction of the center tape
77
PARTY
FOLLOWED ATINTERVAL OF15 YARDS BY
NO. I PARTYTAPING 7FOLLOWED ATINTERVAL OF CROSS TAPE15 YARDS BY 0
NO 2 PARTY_DETECTING (ie V
FOLLOWED AT A
15 YARDS BY w
_0NO. 3 PARTYDETECTING
LEGEND ~ ~ CONVERGING AREA ',
LEGEND- RCN MAN, ADVANCE PARTY i
NCO (C®i).NCO I NO. 4 PARTY
OFFICER ( SUPPLY ANDo -DETECTOR OPERATOR RESERVE
A SST DETECTOR OPERATOR
) -LIFTERQ -SUPPLY AND RESERVE
Figure 38. Mine removal organization of pioneer platoon.
78
ADVANCE PARTY
Personnel Duties1 officer Officer .uprvises ;orT f entire breach-I NCO ing party2 mon NCO directs advaeoo party.
(1) Advance party selects best looetlonn5uipment for breaching. (2) Establishes startingCompaes line for No. I party. (3) Proceeds throughStakes mine field using ineo detector., finds itsMarking lights outer limit and locetes guide stakes orMine dotector lights for No. I party. (4) Establiahes(fro I N 3 location of cross tapes on way back.party)
NO. 1 PARTY
Parsonsal a. Jene fapin1CO Tapes to .-yard lae f orward from base6 men tape as foll.osl
Men Nos. 1, 2, & 3 taped together at 86-;Eq.ifae nt yard spaoing. run out ain tapes from basS electrical line, using electrloal detectors to check
detectors ground immediately to front as they more1,000 yards forward (Pig. 38). Tapes may be run outwhite tape from reels in peci.l holders fastened toin rolls their backs. leaving their hands free.
Mina markers (Detectors operated within 8 yards of eachCompass other may cause interference which decreasesNail, Gd their efficiency. I this caseo the twoPliers side detector men drop bck in line with the
noncommissioned officer who follows 10 to18 yards behind the center detector operator.The ide detector men are taped to the nonco-pmissioned officer to maintain proper 8-yardspacing. )
men oe. 4. 5, b 6, (assistants) follow, pindom tapes and cut them when re.ired, place
arkers on mir.es found along tape lines,. n-vestigate, disarm and out trip wires locatedby detector men, and run out cross tapes whenordered. Cross tapes are set at right anglesto center tope, and extend 5-yards beyond ane..boundary tape.Normally they are placed at pproximately 100-yard icterval to equalize clearing tesks, Ses-eral ross tapes are required for a deep minefield.
NCO in charge comoan ds party and establish-es proper direction of tapes.
Figure 31. Procedure for breaching a mnine field by elec-trical detector.
79
b. nine DetectionOn completion of lane-taping, party ra-turns along boundary tapes to assembly areaand bcomoes a detector party, widening toa 16-yard lane, the 8-yard lane oleared byNo. 2 party.
E0. 2 PARTY
Personnel Line Detection1 NCO As soon as taping prty has advanced8 men 15 yards, No. 2 party starts detecting for-
ward from tape line in right hand lane.Equipment ten Nos. 1, Z,& d, operate electric de-
lectrical teeters each sweeping feet of frontagedetectors working in echelon at 15-yard intervals.
Mine markers Men Nos. 4, 5,& 6, follow in rear asWire aasistants and mark mines found. They ex-
change duties with detector operators at20 minute intervals.
men Noh. 7 & 8, disarm and lift mines,either by hand lilt or by pull with a 50yard wire or rope. Place lifted mines out-side lane boundary tapes.
C00 oonmands party.
N0. 3 PARTY
Personnel Nine Deteotioni NCO When ordered, Walks up center-lire
8 men tape and starts detecting forward fromcross tap in right-hand lane, using same
Equipment proosedure as No. 2 party.z oeetrical On completibn, returns down center-
deteaotor line tape to oross tape and starts Widen-Mine markers ing lane it has Just finiahed to 16 yards,Wire unless No. 4 party is used to widen it.
NO. 4 PARTY
Personnel Reserve and Supplyi NC0 Replaces oasualtie s iy ... an.d losses4 men in eguipment.
lnloads and distributes lane-markirgsupplies.
Ereots lane markers.Cheeks for mines in canverging approach
to lane.Maintains ce2unications.
Figure 32. Procedure for breaching a mine field by elec-trical detector.-Continued.
80
by magnetic azimuth. This detail also locatesall cross tapes.
(2) No. 1 party, using tape, marks -out two8-yard lanes from the base tape. It becomes adetector party on completion of lane taping. -
(3) No. 2 and No. 3 parties each clear a single8-yard lane.
(4) No. 4 party is in reserve and assemblessupplies.
55. Location of MinesThe mine removal organization uses the mine de-tector to locate individual mines. If mine detec-tors are not available or are out of order, thehand search method is employed. Definite or-ganizations for this method will be found in FM5-31 and may be varied for use by the pioneerplatoon. In the event that non-metallic mineshave been buried in the mine field, a probe mustbe used to locate them. The probing should bedone gently and at an angle of 45 degrees, beingcertain to cover every six inches of ground.
56. Removal of MinesA simple method of mine removal is to pull themout by means of ropes. When the mines are lo-cated, the removers attach short lead ropes 'to thehandle, fuze, or cover of each mine. The shortlead ropes are then attached to a main rope sothat several mines may be pulled at once. Leadropes should be of such length that when mainrope is pulled the most distant mines will be pulledfirst, followed successively by those toward thepullers. This method prevents cutting of ropes
81
USING THE MINED67ECTOR TO LOCATE
INDIVIDUAL MINES
____~====:%^RKXN61TAPE -
ROPE REMOVAL ME1HO0
FIN ROPE-I
|==_|iUL~~=~S_____~&~$IN~ TAPE
THE HAND SEARCHMETHOO TO LOCATE
_ - zlIOUALMINES
Figure 40. Locatin4 and removing nlines.
82
leading to more distant mines by the explosion ofmines closer in. Care should be taken to allowsufficient slack in each lead rope so no mines willbe actuated while the ropes are being attached.The main rope should be at 'least 150 feet longso that the mines may be pulled from a safe dis-tance either by 'hand from a sandbagged proneshelter or other suitable cover, or by tying therope to an armored vehicle.
83
Section XVBOMB AND ARTILLERY DUD DISPOSAL
57. Generala. Unexploded shells or aerial bombs may be
found in areas occupied or to be occupied by thebattalion or on routes where they cannot be de-toured. When possible, the bombs, or shells willbe left undisturbed. When a possible time bombis located in a position which cannot be detoured,the bomb is marked and a safe area of 300 yards indiameter designated. No personnel or vehicleswill enter the area until the bomb is disposed of.
b. If necessary, shells and bombs may be de-stroyed in place by the pioneer platoon. All ve-hicles and personnel will be moved to cover, or,if no cover is available, to a distance of at least500 yards from the dud. One man will thenplace a small explosive charge against the dud,being careful not to move or disturb the projectilein any way.58. Explosives NeededThe amounts of explosives necessary to destroyvarious sizes of artillery shells are given below.The same figures can be applied to the destructionof bombs or mortar shells by comparing the diam-eter of the dud with that of the artillery shell andusing the corresponding amount of explosive.
Pounds ofCaliber of Shell TNT
3 7-nmm, 2.24-inch ............................... I7 5-mm, 2.95-inch, 3-inch ................................. 1
155-mm, 4.7-inch, 6-inch .................................. 224 4-mm, 8-inch, 9.2-inch 2..... .................... 2
10-inch, 12-inch-3................................. 314-inch, 16-inch ................. ............... 3
84
Figure 41. Placing charge to destroy dud shell.
NOTE. Three 54-pound blocks of TNT are shown. Ifl-pound blocks are issued, use two.
85
Section XVI
ESTIMATION OF DEMOLITION CHARGES
59. Generala. The pioneer platoon may be called on to ex-
ecute demolitions. These projects will vary be-,cause of the material, structure, weather condi-tions, and similar factors; therefore it is not pos-sible to provide a set of rules that will cover allpossible conditions. Any rules may be consideredas guides and should be tempered by the results oftest shots, past demolition experience, and existingconditions.
b. While formulas (FM 5-25) are used to de-termine accurately the amount of explosive neces-sary to accomplish demolition tasks, it is not in-tended for the pioneer platoon to execute largescale demolitions. For this reason simple rulesthat can be easily remembered and .applied arebetter suited to pioneer platoon work even thoughsomewhat excessive amounts of explosion may beused in some instances. The following para-graphs present some general information on de-molitions relative to tasks that the platoon willnormally perform. It supplements the elemen-tary principles on the use of explosives in FM21-105. For information on more extensive de-molition tasks, see FM 5-25.
c. When TNT is issued in 1-pound blocks in-stead of 52-pound blocks they can be sawed inhalf and used according to figure 42 and the rulesgiven below. If the 1-pound blocks can be made
86
up into a charge of approximately the same di-mensions as that required when using 2-poundblocks, the 1-pound blocks can be used withoutcutting.
60. SteelTo cut steel members by the use of explosives themost important principle to remember is that theexplosive charges must be held in close contactwith each other and with the steel to be cut. Theamounts of explosive required to cut the variousshapes of steel can be determined roughly by thesimple rules outlined below-
(1) Rods. One pound of explosive is used foreach inch of diameter. This rule applies for rodsup to four inches in diameter.
(2) Small rectangular bars. One pound of ex-plosive is used for each inch of thickness and eachtwo inches of width of the widest side of the bar.The explosive is placed on the wide side. Forexample, a bar 1 inch x 4 inches x 10 feet requirestwo pounds of explosives placed on the 4-inch side.
(3) Small built-up box girders. The insideportion of the girder is filled with a tier of explo-sives.
(4) I-beams. One side of the I-beam is filledbetween the flanges with a tier of explosives.
61. TimberThe amount of explosive necessary to cut timberis obtained by using the formula-
40
87
Figure 42. Cutting steel members with explosives.
Note. This figure shows use of Y-pound blocks of TNT.When TNT is issued in I-pound blocks they may be sawedin half and made up in charges as illustrated above.
88
P equals the number of l-pound blocks of TNT.D equals the diameter of round timbers or the
smallest dimension of rectangular timber ininches.(1) Example: How many 1-pound blocks of
TNT are required to cut a log 10 inches in diam-eter ?
(2) Solution: P = 12 X 12 = 3.6 pounds.40 (Use four 1-
pound blocksof TNT.)
62. ConcreteThe amount of explosive necessary to destroy onereinforced concrete stringer in a span of a rein-forced concrete bridge is obtained by using theformula:
P= 3H 2 TP equals the number of 1-pound blocks of
TNT.
H equals the height in feet. MinimumT equals the thickness in value of one
feet. (1) foot.
(1) Example: How many 1-pound blocks ofTNT are required to destroy a reinforced con-crete stringer 2 feet high and 10 inches thick?
(2) Solution: P= 3X2X2X 12 (twelveI-poundblocksofTNT)
89
DETAIL OF A METHOD OFTAMPING CHARGE TO
DESTROY A REINFORCEDCONCRETE STRINGER
CHARGES LAID TODESTROY CONCRETE
STRINGERS
EXPLOSIVE PLACEDTO CUT TIMBERS b i PLACE CHARGES DIRECTLY
OVER STRINGERS ANDIN EXACT CENTER
OF SPAN
Figure 43. Destroying reinforced concrete stringer andtimber with explosives.
90
63. Cratersa. To form a crater in a road, holes are dug in
a line across the road extending to natural bar-riers on both sides. The holes should be 5 feetapart from center to center. The charge neces-sarily will vary with the condition of the ground;a normal charge is 10 pounds of explosive perfoot of depth in each hole. For example, 50pounds of explosive will be placed in the bottomof a hole 5 feet deep.
b. The explosive should be tamped well withearth, mud, or water. The charge should beprimed by two methods to insure simultaneous de-tonation of all charges. This will avoid the ne-cessity of digging up the charges or placing newcharges in case the charge fails to detonate.
c. At times culverts will be found in locationsadvantageous for road craters. A culvert maybe utilized in blowing a crater by observing thespacing of charges and the amount of explosivesper charge as outlined in a above. This proce-dure is effective where the distance from the sur-face of the road to the top of the culvert does notexceed five feet. When distances greater thanfive feet are encountered, other considerations en-ter which make the amount of explosives requiredtoo great for use by the pioneer platoon. Theends of the culvert must be blocked and welltamped.
91
PREPARATIONOFCRATER
DOUBLE PRIMING PRIMACOROAROUND ONE
Beg / >s o.- ~ ~ ~ ~ ~ .. NL ~ UNIT Or EX-
REEL WIRE \ \ / CAP WIRE\ PLOSIVE INREEL W17RE (C.1 -~~~IRE EACH CHARGE.
ELECTRIC ORNONELECTRIC CAP ETRC
Figure 44. Preparation of craters.
92
INDEX
Paragraph PageAdvance guard ... ................ ........ 8 9A-frame ........................................ 44 56Air attack ............................ ..... 11,20 14,28Air compressor operator .......................... 8 9Approaches to fords ........................ .......... 38 46
Bars, demolition of steel .......................... 60 91Bed, stream ......................................... 38 46Bents ........................................ 43 52Bivouacs:
Air attack ........................................ 20 28Duties of personnel ........................... 19 25Leaving ...................................... 19 25Living in ........................................ 19 25Occupation ............................. .......... 15-17 19-23Prior to occupation .......................... 15, 16 19, 21Protection ............................................ 17 23Raids ........................................ 21 28Security ................................. 18, 19 24, 25
Blackout precautions ........................ .... 18 24Booby traps ................................... 16, 28 21, 34Brace, knee ........................................ 43 52
Bridge:Capacity ........... ............................. 48, 49 64, 65Cards ......... ............................ 6, 49 5, 65Check list ........ ........................... 5 3Lanes ................................................ 49 65Nomenclature .................................... 42 52Passage ........................................ 48, 49 64, 65Post ...................................... .. 45 61Reconnaissance ................................. ,. 5 3Report forms ...................................... 6Strengthening ...................................... 42-45, 47 52-61, 62Stringers ..................... 1......... . 1,45, 49 1, 61, 65Support ............................ ............ 43 52
Cable ferry ........................................ 41 50
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Paragraph Page
Capacity:Bridge ..................... ................. 48, 49 64, 65Winch ........................................ 33 39
Cards:Bridge ...................................... 6, 49 5, 65Road .................................................... 6 5
Chain, safe working load of .................... 32 38Check list:
Bridges .................................... 5 3Combat readiness .................. 19 25Contacts .................................... 19 25Cross-country routes ........................ 5 3Duties on movement:
Air compressor operator ............ 8 9Assistant section leader ........... 8 9Driver ........................................ 8 9Platoon commander . ............... 8 9Platoon sergeant....................... 8 9Radio operator .,-... .......... 8 9Section leader.............................. 8 9
Fords ........................................ 5 3Leaving a bivouac. ............................. 19 25Living in a bivouac ...................... 19 25Mined areas ........................................ 5 3Roads .................................................. 5 3Security in bivouac ... ...................... 19 25
Combat areas:Occupation of ......... .................. 24 . 30Reconnaissance of .............................. 23 30
Combat readiness ............................... 19 25Concrete, demolition of ............................. 62 93Construction of obstacles .......................... 25 32Contacts .......................... 19 25Corduroy roads ........ ........................... 35 41Crater .......................................................... 63 95Cross-country route reconnaissance......... 5 3Crossing, stream ................ ................... 38 46
Deception ........................................ 51 76
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Paragraph Page
Demolition:Concrete ........................................ 62 93General ............................................... 59 90Steel .............. .......................... 60 91Timber ........................................ 61 91
Drivers, duties on movements ................ 8 9Dud, disposal of ........................................ 16, 52, 58 21, 76, 87Dummy position .......... ............. 26, 52, 53 32, 76, 78Duties of personnel:
Bivouac ........................................ 19 25Movement ...................................... 8 9
Equipment - .............................. 2 1Expedient:
Road ........................................ 34 41Stream crossing- ...................... 38 46
Explosives:Demolition ........................................ 59-63 90-95Dud disposal ........................ -........ 58 87
Ferry, cable ........... .................. 41 50Fire fight .................................... 27 34Flank guard ......... ............................. 12 16Floating ...................................... 39 48Fordability ........................................ 38 46Fords:
Approaches to ............................... 5, 38 3, 46General ............................ 5, 38 3, 46Reconnaissance of .......................... 5 3Stream, bed of ............................... 38 46
1Formations ......................................... 19 25Forms:
Bridge report ................................. 7 6Road report .................................. 7 6Technical report ........................ ....... 7 6
Fougasse ....................................... . 53 78Frame, A- ...... .................... .. ............ 44 56
Girders, demolition of steel .................. 60 91
95
Pararaph Page
Guard:Advance ............................................ 8 9Bridge ......................................... 6 5Flank ........................ .... 12................ 12 16Rear . ................................... 28 34Road ......................................... 6 5
Halts ...................................................... 13 16
I-Beams, demolition of. ............................. 60 91Information, reconnaissance ...................... 7 6Knee brace ..................... .............. 43 52
Lanes, bridge . ................ ................. 50 74Location of mines ................................... 55 84Loads:
Chain ................................... ..... 32 38Towed ....................... ................. 50 74Rope ................................ ........ 32 38Vehicle ........................................... 48, 50 64, 74
Mined areas ........................................ 5 3Mines:
Bivouac ........................................ 16 21Location of ...................................... 55 84Removal of ........................................ 54-56 80-84
Mission:Bivouac ........................................ 15-17 19-23Demolition ........................................ 59 90Flank guard ........................................ 12 16General ........................................ 2-5, 29 1-3, 36Mines .................................... .... 54-56 80-84Movements .................................-...... 8, 13, 14 9, 16, 18Occupation of combat area................ 24 30
Movements:Formation .................................... 10 12General ........................................ 8 9Halts .......................... .............. 13 16Rail ........................................ 14 18Retrograde ........................................ 28 34Security ........................................ 11 14W ater ........................................ 14 18
Nomenclature, bridge ................................ 42 52
96
Parareph Pa.
Obstacles:Construction of .................................... 25 32General ...................... 3 1Reduction of .........................-.. . .... 13, 25 16, 32
Occupation:Bivouac ..................... ................ 15, 16 19, 21Combat area ........................................ 24 30
Operation of winch ................................ 32 38O verlays ......... ...................................... 7 6Passage, bridge ..................................... 48, 49 64, 65Platoon commander on movement ............ 8 9I'latoon sergeant on movement ................ 8 9Position:
Dummy .......-....-..-................ 26, 52, 53 32, 76, 78Gun ...... ....... . 26 32In readiness .......................................... 22, 22, 24 30
Post, bridge ............... ................ 45 61Preparation of gun positions ...................... 26 32Protection in bivouac ......... :.....-.. ..... 17 23Radio operator, duties on movement ........ 8 9Rafts .................------- - ----------------------------- -------- 40 50Raids, bivouac ..................................... 21 28Rail movements ..................... . .............. 14 18Readiness:
Com bat ........................................ ...... 19 25Position in ...................................... 22, 24 30
Rear guard ......................-.............- ---- 28 34Reconnaissance:
Bridge .. .......... .............----------- -... 5 3Cross-country route ............................ 5 3Combat area ................ - -................ 23 30Ford ..................... ........ :- .... 5 3General .......-.......... . .. ...............- 4 3Mined area ....................--................ 5 3Reports on .... - ---................................. 7 6Road ................................. ----------------------------- 5 3
Reduction of obstacles ....................... 13,25 16,32References, platoon training ............._--- .. 30 36Removal of mines ......- --............................. 54-56 80-84
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Paragraph Page
Reports:Forms ........................................ 7 6Reconnaissance ................................ 7 6
Retrograde movements ......................... 28 34Roads:
Cards for..................................... 6 5Corduroy ........................................ 35 41Expedients ........................................ 34 41General ........................................ 5 3Guards ........................................ 6 5Reconnaissance of................................ 5 3Report forms ................................... 7 6Tread ...................... .................. 37 44W ire mesh ............................... .... 36 43
Rods, demolition of steel .......................... 60 91Rope:
Safe working load of.......................... 32 38W ire ...................................... .. 32 38
Routes, cross-country ........................... 5 3
Safe working strength:General ........................................ 31 38Chain ........................................ 32 38Rope ........................................ 32 38Winches .................. .................. 33 39W ire rope ......................... ........... 32 38
Section leader:Duties on movement.......................... 8 9Duties of assistant section leader...... 8 9
Security:'Against air attack .............................. 11 14Bivouac ........ ............................... 18, 19 24, 25On march ................. .................. 11 14
Shear pins, winch .................................. 33 39Sketches ........................................ 7 6Spans:
Long ........................................ 50 74Short ........................................ 50 74
Steel:Bridge stringers ................................. 49 65Demolition of ...................................... 60 91
98
Paragraph Page
Stream:Bed ........................................ . 38 46Crossing ........................................ 38 46
Strengthening bridge .............................. 42-45, 47 52-61, 62Stringers:
Bridge ..............................-......... 1, 45, 49 1, 61, 65Corduroy road ..............................--... 35' 41
Support, bridge ................................. 43 52
Technical references .................................. 30 36Timber, demolition of .............................. 61 91Towed loads ................................... 50 74Training of personnel .............................. 3,29, 30 1, 26, 36Training references 30 36Trap, booby ...................................... . 16, 25 21, 32Tread, road ........................ -----------------------............ 37 44Trestle bents ................................... 43 52
Vehicle:Loads ....................................... 48, 50 64, 74Weights ........................................ 48 64
Wedging ........................................ 43 52Weights of vehicles ................................ 48 64Winches:
Capacity ........................................ 33 39Operation ........................................ 33 39Shear pin ........................................ 33 39Water movements ....... ........................ 14 18
Wire-mesh roads ............... :...................... . 36 43Wire rope, safe working strength of ........ 32 38
* U S. GOVERNMENT PRINTING OFFICE. 1944-61a837
99