BRIDGES

Discussion in 'Bridges' started by Trux, Aug 30, 2010.

  1. Trux

    Trux 21 AG Patron

    BRIDGES

    This page lists bridging and assault crossing equipment. Other engineer equipment is also listed.

    Bridge Pictures


    BRIDGE AND ASSAULT CROSSING EQUIPMENT

    RECONNAISSANCE BOATS
    These were inflatable boats used by engineer officers for the reconnaissance and survey of obstacles. Often referred to as rubber dinghies they were in fact made of rubberised canvas.

    Reconnaissance Boat MkI
    This was a two man boat. It was light and easy to handle on land but somewhat small for its role on water.

    When inflated it had the following dimensions.
    Length - 6 foot 8½ inches
    Width - 2 foot 8½ inches
    Height- 1 foot 3 inches
    Weight – 40lb

    The Reconnaissance Boat MkI came equipped with two paddles. For transport it could be packed into a bag 30 inches long and 15 inches in diameter. This could easily be lifted and carried by one man.

    Each divisional Field Park Company RE carried 32 reconnaissance boats.
    Each Bridging Company carried 16 reconnaissance boats.


    Reconnaissance Boat MkI
    This was a three man boat. The extra man allowed for two men to row while the third surveyed and took notes or measurements. Weight was increased to 112lb. A great advantage was that this boat could be powered by an outboard motor. In this case it could carry only two men.


    KAPOK FOOT BRIDGE.
    The basic kapok bridge was designed as an infantry assault bridge but the equipment could be used in a variety of ways.

    Infantry Assault Bridge.
    The components were simple, a number of kapok filled floats supported a wooden walkway.

    Floats were each 6 foot 6 inches long.
    Decking sections were each 6 foot 6 inches long and 1 foot 10½ inches wide.
    A bay of one float and one decking section weighed 1cwt.

    Two men carried each float and one man carried each length of decking. A float was attached to each end of a length of decking using simple catches. The completed bay was then pushed out into the water. A second decking section was attached to the shore end of the first bay and then a float was attached. The bridge was progressively pushed out into the water until the far bank was reached. The maximum practical length was 150 foot, but this was only in still water. Any tide, current, flow or wind would make this length hazardous or impossible.

    Thirty bays of kapok bridge could be carried in a 3ton GS lorry. Although this was only half of the lorries weight capacity the bulk of the equipment made it impractical to carry more.


    Attachment, Carrier Flotation, Kapok, MkII.
    Kapok floats used with special fittings could be used to float a carrier across a water obstacle. The fittings could be used with any type of Carrier, except the T16, as long as it was a welded type and was correctly waterproofed. The Carrier, Armoured Observation Post, had to have the charging engine removed since it was mounted outside the body, and it required an extra float at the rear.

    Eight brackets were clamped to the carrier, two at the front, two at the rear and two at each side. Nine kapok floats were used, three vertical at the front, two vertical at each side and two horizontal at the rear.


    Flotation of a 6pdr AT Gun.
    It was possible to float a 6pdr AT gun, but this was hazardous in any but the stillest water. The trail legs were held open by a 4foot 10inches long piece of timber. Eight floats were required, three lashed under the trail, four lashed along the barrel with one lashed at right angles under the muzzle. The guns drag ropes can be used for lashings. The gun should be pulled across from the far bank. The crew can be carried but not ammunition.

    Raft for 15cwt Truck.
    It was possible to construct a raft to carry a 15cwt truck but this was even more an emergency measure than was the flotation of a 6 pdr AT gun. Twenty seven floats were lashed together in three layers. Eight decking sections were lashed on top to form two trackways. Loading such a raft was difficult without ramps and the lack of rigidity caused problems.



    ASSAULT BOAT MKIV
    Assault Boats were folding boats with a plywood floor, wooden gunwales and canvas sides. Mk IV was double ended although there was a bow, which was strengthened and had a mooring line and ring, and a stern which had a rowlock for the steering oar. Being double ended did make it easier to use as a ferry when it was towed backwards on the return journey. No seats were provided, crew and passengers knelt on the floor (on one knee).

    The assault boat was carried folded and strapped flat. It was readied for use by
    - undoing the straps holding the gunwales to the floor
    - fitting the removable bow and stern struts
    - raising the canvas sides and holding them in position with six folding struts which were pinned into the underside of the gunwales.

    When assembled it required six men to carry it to the water.

    There was a crew of three. One man commanded and was the steersman, using an oar through a rowlock in the stern. Two others were oarsman who actually used paddles. Two further oarsmen were detailed from the passengers.

    The following procedures were laid down
    - The boat was launched and held with its stern against the bank.
    - The boat NCO boards first and takes up his position in the stern.
    - The two boat crew board next and take up their positions near the bow.
    - Two of the passengers will be detailed to hold the boat to the bank and will board last.
    - The section Bren gun will be carried in the centre of the boat

    There were three ways of propelling the assault boat.
    - it could be rowed with four men using paddles.
    - it could be powered by a Seagull outboard motor. This was noisy and prevented any surprise.
    - it could be ferried by using the 40 fathom of 1½ inch ferry cable provided. This method usually relied on the four men who would normally used the paddles hauling on the cable instead. This method could only be used on crossing of less than 100 feet and needed a cable taking across the obstacle first.

    Assault boats were operated by infantry battalions although the boats were provided by the Royal Engineers and Royal Engineer personnel trained and supervised.

    The Assault Boat MkIV had the following dimensions
    Length - 17 foot 6 inches
    Width - 6 foot
    Height - 2 foot 8 inches
    Weight - 415lb

    The boat would carry fifteen fully equipped men in addition to the crew of three. This represented an infantry section plus a proportion of supporting personnel such as platoon headquarters, signallers, pioneers etc.

    A Divisional Field Park Company Royal Engineers carried 48 assault boats.
    A Bridging Company carried 24 assault boats


    Attachment MkI, Carrier Flotation (Assault Boat).
    This simple attachment enabled two assault boats to float a carrier across a water obstacle.

    Two light steel beams were clamped to the sides of the Universal carrier. Struts connected the beams to the bottom of the bearers of the assault boat. The clamps were quick release so that the carrier could go into action very quickly once it had reached the far bank. Equally important was the fact that the quick release clamps allowed the complete assembly of boats and struts to be lifted off and return for another carrier without delay.

    The boats and struts needed to be fitted on dry land, preferably near the water but out of sight of the enemy. It was also important to find a launching site with banks which were not so steep as to cause the boat to swamp when entering the water. The same was true at the far bank. A landing site was required which gave an unhindered passage to the somewhat unwieldly boats and was not so steep as to swamp them. Canvas dodgers could be fitted to the bow and stern to help prevent swamping.

    All Carriers had to be of the welded type and might need waterproofing.

    Propulsion was normally by the Carriers own tracks.



    FOLDING BOAT EQUIPMENT MkIII.

    Decked Rafts.
    The Folding Boat Equipment provided a rapid means of providing a bridge which would carry most of the vehicle in an infantry division. It was very versatile and the following were official modes:
    The Decked Raft was the basic element of the FBE bridge and of most of the rafts. It consisted of two folding boats with four roadbearers fitted to the gunwales. Near the ends of each bearer was a metal plate with a socket in it. This fitted over pins on the boat gunwales. When all four bearers were in place deck panels were fitted between pairs of bearers, resting on a lip. For speed the centre deck panels could be omitted, the outer panels being sufficient to carry most vehicles.

    Decked Raft Class 5.
    This was simple to build and operate but needed landing stages on both banks. It was a single floating bay of two boats and a standard 19 foot 6 inch length of roadway and so could later be incorporated into a bridge. The landing stage was usually a half floating bay of one boat and a standard roadway length resting on a shore transom at the shore end. More elaborate landing bays using trestles could be erected if necessary. The decked raft could be operated as a ferry with cables strung across the water obstacle. Power could be outboard motors, winches, or paddles.

    A Class 5 raft could carry 6 pdr anti tank guns, carriers and 15cwt trucks. Vehicles could simply drive forward onto the raft and drive forward off at the other side. This was not true of all rafts.

    Components required for the raft were
    2 X boat
    4 X roadbearer
    15 X decking panels
    4 X raft connector.

    Decked Raft Class 9.
    This was as for Decked Raft Class 5 but used two bays. Being Class 9 it could carry a loaded 3ton lorry.

    Shore Loading Decked Raft Class 5.
    This was single bay but with a half floating bay attached. The outer end of the half floating bay was fastened to a shore transom which rested on the bank when loading and unloading. If the banks were a suitable height the shore loading raft could be used without landing stages and could thus come into action more quickly. A further advantage was that the raft could be free ranging and be rapidly changed from one crossing point to another. A disadvantage was that the raft had to turn round in mid stream to allow the half floating bay to be brought against the far bank. This in turn meant that vehicles had to reverse onto the raft.

    Components required for the raft were
    3 X boat
    8 X roadbearer
    30 X decking panels
    2 X raft connector.
    1 X shore transom

    Shore Loading Decked Raft Class 9.
    This consisted of two Class 5 Shore Loading Rafts with the two half bays on the outside. This could carry 3ton lorries. Having a half bay at each end meant that turning in mid stream and reversing onto the raft were not necessary.

    Ferries.
    Any of the decked rafts could be used as a ferry. In that case a line must be taken across the river by the dinghy or a folding boat and fastened to holdfasts on each bank. A ferry set consisted of:
    1 X cable drum with 100 fathoms of 1” cable.
    2 X 113 fathom coils of 2” manila hawser.
    2 X 2” double blocks
    2 X 1” snatch blocks
    4 X earth holdfast anchors.
    The raft can then be powered by whatever means is available. Oars and propulsion units are not suitable because of a lack of space but outboard motors and winches can be used. If necessary the raft can be powered by men hauling on the cable.


    Bridge Class 9.
    Any number of Decked Rafts Class 5 could be connected to make a bridge, officially up to 240 foot long but longer bridges were built. Each end of the bridge needed a half floating bay and a trestle bay with ramps.



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    The FBE bridge was for assault use and should be built immediately after a successful assault crossing in order to move divisional vehicles across the obstacle. It is important that as much design and planning be done in advance as possible but designs and plans may have to be altered after a close inspection of the site, or as a result in changes in the tactical situation.

    Since time is important vehicles should be off loaded as close to the construction point as possible. The following outline should be followed:
    - A parking area should be chosen and signposted. It should be off the road but have easy access.
    - Lorries should be called forward as required and park as close to the construction site as possible. Vehicles should be unloaded as their stores are required and stores should not be laid out on the ground.
    - Work should be carried out on the decked rafts and the near bank landing stage simultaneously. It may be possible to work on the far bank landing stage but this will probably have to wait until the bridge is complete.
    - Rafts can be added to the bridge as they are completed.

    The Folding Boat.
    The Folding Boat is constructed of plywood and canvas. The floor is covered with wooden slats and the bottom and sides have rubbing strakes for protection. A timber baulk runs down the centre of the floor and this provides a firm base for the spreaders. To open a boat requires twelve men. It is laid on the ground with five men on each side and two men in the boat. The sides are then pulled upwards and outwards until the men in the boat can fit the spreader tubes from the centre baulk to the gunwale clamps. Twelve men are then required to carry the boat to the water.

    The folding boat can be used as an assault boat in which case it can carry eighteen men.

    The folding boat had the following dimensions
    Length - 22 foot
    Width - 6 foot 8 inches
    Height - 2 foot 9 inches
    Weight - 940 lb.

    Each boat has the following
    5 X oars
    1 X boathook
    1 X bailer
    1 X anchor
    1 X bouy with line
    2 X dodger to fit over the ends of the boat to keep water out.


    The Road Bearers.
    Road bearers were steel girders each with four square plates with sockets to correspond with pins on the boat gunwales. Bearer had ledges at the bottom to support deck panels, and had eighteen holes, one foot apart, to reduce weight.

    Length - 19 foot 6 inches
    Height - 10½ inches
    Weight - 380 lb

    The Deck Panels.
    Deck panels were made up from four planks of Douglas Fir fasten together. Five panels were fitted between each pair of bearers. They were located by small welded distance pieces on the bearer and by dowels on the panels fitting into slots in the bearers.

    Length - 3 foot 10½ inches
    Width - 2 foot 7½ inches
    Thickness - 1¾ inches
    Weight - 78 lb

    The Bay Connectors.
    Rafts were connected to each other using raft connectors which were clamps fitting over pins near the end of each bearer. This allowed for vertical movement as vehicles passed over the bridge.

    The Trestles.
    The trestle supported the roadway at the shore ends of the bridge and allowed for some adjustment for height. A transom was supported on two legs and a saddle fitted to the transom to accommodate the road bearers. An NCO and 6 men can erect a trestle in ten minutes.

    Where a water obstacle is too shallow, has sand banks or obstacles, or even where there is no water, a bridge can be constructed entirely from trestle equipment. This is expensive in equipment since the trestles from several bridges will be needed.

    Trestle Transom
    This was a steel box girder with slots at each end to accommodate the supporting legs.
    Length - 13 foot 5 inches
    Width - 6 inches
    Height - 10 inches
    Weight - 210 lb

    Transom Saddle.
    A steel beam with location points for road bearers. This was clamped to the top of the transom.
    Length - 11 foot 3 inches
    Width - 4½ inches
    Height - 1½ inches
    Weight - 50 lb

    Trestle Legs.
    These were steel box sections with holes drilled every four inches to accommodate pins to support the transom at the required height. Should this height need to be adjusted jacks could be fitted to the legs and transom and the transom thus raised or lowered.
    Length - 10 foot 10 inches or 7 foot.
    Width - 5 inches
    Height - 3 inches
    Weight - 150 lb

    Shoes.
    These were circular metal supports for the legs. They fastened to the base of the legs by pins so as to allow some articulation to accommodate uneven surfaces.
    Diameter - 1 foot 4 inches
    Weight - 22 lbs

    Struts.
    Steel telescopic struts were used to brace the legs. These were fastened to the top of each leg and then fixed to the bank with spikes.
    Length - Variable from 22 foot 6 inches to 13 foot.
    Weight - 22 lb.

    The Ramps.
    Ramps were provided to allow easy access to the shore ends of the landing bay. They were deck panels permanently fitted to a tapering base with trunnions to fit onto a shore transom.
    Length - 3 foot 4 inches
    Width - 3 foot
    Thickness - 4½ inches tapering to 2 inches

    The Shore Transom.
    A steel shore transom was used on each shore to locate the road bearers and the ramps. Much as a transom saddle but more substantial.
    Length - 10 foot 6 inches
    Width - 6 inches
    Height - 4 inches


    The Folding Dinghy.
    The folding dinghy was part of the Folding Boat Equipment and was intended for use in bridging operations. It was constructed from plywood panels hinged together with canvas. It could carry three men and could be carried by two. Erection was a matter of seconds. The sides were pulled upwards and outwards and then held in place with two wooden thwarts which also served as seats. Two oars were supplied.

    Dimensions when open.
    Length - 10 foot 3 inches
    Width - 4 foot 3 inches
    Height - 1 foot 8 inches
    Weight - 100lb


    The Tracked Raft.
    The Tracked Raft used two folding boats but otherwise was a different equipment. It could not be used as part of a bridge or in any but the basic form. Two folding boats were fitted with tracked raft transoms which fitted on the outer gunwale pins. Two steel lattice trackways are clamped onto the transoms, facing fore and aft rather than across the boats. Four trackways are hinged to the ends of the centre trackways to form ramps and then the ramps are braced into the desired position. Note that ramps must be resting on the banks before vehicles can cross them.

    A tracked raft requires:
    2 X boat plus accoutrements
    2 X transom
    6 X trackway (two centre trackway and four ramps, all identical except for clamps)
    2 X set of ramp bracing members (long tie bar, A frame and short tie bar).
    2 X set of trackway bracing members (2 X tie bar and 2 X A frame).
    8 X 2” breastlines.
    4 X wheel chocks to secure the load.

    The minimum detachment for assembly is an NCO and 11 men. Construction time is 10 minutes using the following procedure:
    - ten men assemble and launch the two boats and two men moor them to the bank with breastlines and pickets.
    - The boats are positioned at right angles to the shore and raft numbers, 1 to 4, get into them.
    - numbers 5 to 8 pass the transoms to the raft numbers who place them into position, offshore end first.
    - Numbers 1 to 6 carry and fit the upstream trackway and numbers 1 to 3 remain on board.
    - Numbers 4 to 9 carry and fit the downstream trackway.
    - Numbers 1 to 3 and 7 to 8 fit guides and articulation members
    - Numbers 1 to 6 carry and fit the upstream ramp and numbers 1 to 3 remain on board to adjust the ramp and fit bracing
    - Numbers 4 to 9 carry and fit the downstream ramp.
    - The boat is turned round so that the remaining ramps can be fitted.

    The tracked raft can be powered by;
    - Oars. Five oars are provided for each boat, usually two are for steering.
    - Propulsion unit. An engine is carried in the bows of the boat and the propulsion unit fitted to the stern. Usually only one set is used per raft.
    - Seagull outboard motor. This is clamped to the stern of one of the boats.

    Transport.
    The Tracked Raft was carried by
    - A 3ton 4 X 4 GS lorry which carried the superstructure
    - A FBE MkII trailer which carried two boats and the two transoms.

    The bridge loads were
    - 3ton 6 X 4 FBE lorry carrying a complete landing stage unit
    - 3ton 6 X 4 FBE lorry carrying a complete floating bay unit
    - 3ton 4 X 4 GS lorry carrying 8 rolls of trackway for the approaches
    - 15cwt GS truck carrying ferry gear, auxiliary equipment and a dinghy



    Stormboat.
    The stormboat was intended for the assault crossing of wide and fast flowing rivers. It had an oak frame and plywood sides and bottom. Seat/tracks extended down both sides and served both as seats and tracks for guns or light vehicles. There was a false floor to allow any water that was shipped to flow into the bilges. It could carry eighteen fully armed men in addition to a crew of two, although twelve fully armed men was the normal load under operational conditions. The maximum speed was 20 knots when empty or 6 knots when fully laden. It was particularly useful since it could carry a jeep or a 6pdr anti tank gun and ammunition. To assist in loading and landing it could be equipped with steel ramps. The inside ramps rested on the seat/tracks and were fixed into position. The outer tracks could be swivelled so that they rested inside the boat, or they could be extended forward and fixed into one of three positions. These allowed loading and landing at up to banks 3 foot high. A centre ramp could be fitted between the ramps to act as steps for personnel.

    The stormboat was powered by a 50hp outboard motor. This was mounted on the stern on a swivel mount. This allowed the motor to be turned 90 degrees for steering. The mount also tilts for and aft so that the motor will tilt if it strikes the river bottom or an obstacle, and the motor can be tilted right over and brought into the boat.

    This equipment was operated by Royal Engineers as it required some skill. When loading it was important that the boat be sufficiently far from the bank to ensure that it did not settle into the river bottom as the guns or jeeps were loaded. The boat had also to be held steady and square with the bank. This was done by driving spiked through holes in the ends of the ramp and by breastlines fastened to the stern of the boat. In very fast flowing rivers it may be necessary to find an inlet or other water sheltered from the current.

    Length - 20 foot
    Width - 6 foot 6 inches
    Maximum draught - 2 foot 3inches
    Weight - 1,500lb

    Equipment included an outboard motor, ramps, canvas dodger, breastlines and wheel chocks.

    Three boats could be carried nested in a 3ton 4 X 4 GS lorry. A special 18 inch high wooden frame was needed to lift the boats above the lorries wheel arches and so that the widest (top) part of the boat cleared the body sides. The lorry tilt and frame could not be fitted. The length of the boat meant that the lorry tailboard had to be lowered or removed. The ramps and motors were carried in the top boat and covered with tarpaulins.


    CLOSE SUPPORT RAFT.
    A Close Support Raft MkII was introduced and this gave a higher free board. Either the MkI or MkII could be made into a Class 12 Close Support Raft by using a Bailey centre pontoon.

    The Close Support Raft was developed in 1943 to carry vehicle across water obstacles in the early stages of an assault river crossing. It was expected that there would be considerable demand for these in NW Europe. The design used the experience of a variety of earlier rafts which used a variety of components from other bridging systems. It was designed specifically as a raft and was not intended for use as a bridge. Its features included
    - light road way bearers which were easy to manhandle.
    - rapid construction using few personnel
    - ease of operation with a small crew
    - shore loading in that it had ramps and did not require landing stages or prepared landing sites
    - free ranging in that it could be powered by propulsion units and was not limited to one crossing point.

    Construction
    The Close Support Raft MkI used MkV or MkV* pontoons with a specially designed saddle. The pontoons were mounted on wooden sledges with steel runners so that when unloaded from the pontoon lorries they could be towed across country by any armoured tracked or half tracked vehicle. Four road bearers were each assembled from two sections and fitted to the pontoons. Ramps were fitted at each end and propulsion units fitted.

    The Close Support Raft was Class 9. This meant that it could normally take four wheeled vehicles up to 9 tons but could carry six wheeled vehicles and tracked vehicles of greater weight. This included all the tactical vehicles of an infantry battalion plus armoured cars and Quad tractors with 17pdr anti tank guns. Although two pontoon piers were normally used it was possible to add a third pontoon pier. This did not increase the capacity but did give a greater freeboard and allowed an extra propulsion unit to be fitted. Three part pontoon piers using Bailey centre pontoons were authorised and this did increase the capacity to Class 12.

    The ramps were connected by cables so that when one ramp was lowered the other was raised. It was possible for the vehicle being carried to operate the ramps by driving slowly on to them but it was generally wiser to send a man. One mans weight was sufficient to operate the system.

    A Close Support Raft MkII was introduced and this gave a higher free board.


    BAILEY BRIDGE
    The Bailey Bridge became almost a universal bridge equipment, capable of being used in a wide variety of roles and replacing all other equipment except the FBE in forward areas, and supplementing other equipment in rear areas. It could be built in an infinite variety of lengths and load classes. It could be built by almost any engineer unit and could be built without machinery. It could be carried in standard 3ton GS lorries. It could also be used for pontoon bridges and rafts. It was adopted by the US Army and others, and remained in service for many years. In only slightly modified form it is still in use today.


    The basic unit of the Bailey Bridge was a 10 foot length using he following components
    - A panel which was a steel frame 10 foot by 5 foot 1 inch. These were fastened together with standard panel pins 8 1/4 inch long and 1 7/8 diameter.
    - A steel I Girder transom which was 18 foot long, 10 inches high and 4 ½ inches wide. These were clamped to the panels using transom clamps. Transoms had five sets of lugs on the top surface to locate the roadway stringers. There were four holes drilled through the transom to allow the transom to be carried using lifting bars.
    - Five stringers, each consisting of three connected girders, were laid across the transoms. The stringer was 10 foot long, 1 foot 9 inches wide and 4 inches deep. The two outside stringers were button stringers which had buttons along the outside edge to locate the roadway chesses.
    - Chesses were of wood and were 12 foot long, 8 ¾ inches wide and 2 inches deep. These were laid across the stringers and located by the buttons on the button stringers.
    - Ribands, 6 inches by 6 inches, 10 foot long and chamfered on both sides, held the chesses in place.
    - Rakers were fastened to the top run of the panel and a lug near the end of the transom. These kept the panel vertical.
    - Tubular Sway Bracing was fitted under the roadway. A brace ran from one end of the lower run of a panel to the diagonally opposite end.

    The bridge could be strengthened in a number of ways.
    - Extra transoms could be added. There were normally two per bay but four could be used.
    - An extra truss of panels could be fitted outside the first. The panels were fastened together with bracing frames 4 foot 3 inches long and 1 foot 9 inches wide.
    - A third truss could be added outside the first two. This did not have bracing frames.
    - Extra stories of panels could be added over the lower ones.

    Each end of the bridge was supported by end posts which fitted onto a base plate 4 foot 7 inches by 3 foot. This had bearings to accommodate single, double or triple trusses.

    Footwalks could be fitted either side of the bridge. Bearers 3 foot long were fitted to each end of the transom. Footwalks were 10 foot long by 3 foot wide and made up of 6 inch wide strips of wood 3 inches apart and fasten by four battens. Handrails could also be fitted.

    Ramps were used at either end of the bridge. These were 10 foot long but two could be fitted together and rested on a transom.

    Weights of components.
    Panel 570lb
    Transom 445lb
    Transom Clamp 7lb
    Rakers 18lb
    Sway Bracing 65lb
    End Posts 130lb
    Base Plate 400lb
    Bearings 70lb
    Footwalks 98lb
    Footwalk Bearer 20lb
    Handrail 7lb
    Stringers 133lb
    Button Stringers 190lb
    Chesses 50lb
    Ribands 95lb




    IMPROVISED RIVER CROSSING EQUIPMENT.
    It was a principle that every effort should be made to force a crossing if a river obstacle was reached. To delay only allows the enemy to organise a defence and necessitate a set piece assault. Only a small force on the far bank can yield great gains. The following were official uses of readily available military material. Obviously many other improvised floats and rafts could be utilised.

    Groundsheets.
    Groundsheet float.
    Two men could use their two waterproof groundsheets to make a float to carry their equipment while they swam across a water obstacle. The uniforms and equipment are packed into the groundsheet and the two rifles are laid lengthways on either side of the equipment to provide ballast and rigidity. When tightly fastened this should remain afloat long enough to cross a river. The men should swim and push the float ahead of them. If one man cannot swim he can use the float for support while the other man swims and tows the float on a line. It should be possible to carry a Bren gun or 2” mortar instead of rifles.

    Groundsheet raft.
    Twenty four ground sheets filled with straw or bracken can be used to make a raft. Twelve such ground sheets should be tied together to make a float and two floats tied alongside each other to make the raft. A deck of bridge chesses or similar timber can be used to make a flat deck with an area of 6 foot by 11 foot. This will carry 1800lb.

    Tarpaulin.
    Tarpaulin sheet float.
    A standard 20 foot square tarpaulin sheet can be filled with straw or similar material to make a float 4 foot 6 inches by 4 foot 6 inches by 1 foot 6 inches. This can be made in 15 minutes and will carry three men.

    Tarpaulin sheet raft.
    Four tarpaulin sheet floats are lashed together with poles or spars, leaving a 3 foot gap between floats. A deck of planks can be laid over the spars to make a raft 15 foot long and 12 foot wide. This will carry 24cwt.

    Lorry tilt.
    The frame and tilt from a 3ton GS lorry is inverted and the frame stiffened with thin timber. Bearers of 4inch by 2 inch timber are laid on the frame and trackways of 6 inch by 2 inch timber laid on them. This will take 15 minutes to build and will carry a 6pdr gun, its crew and eight boxes of ammunition.

    Field Artillery.
    A standard 25 pdr field gun or a 6 pdr anti tank gun can be stripped and the components carried in rafts or boats which would not carry the entire piece. A 25pdr can be stripped in 20 minutes and reassembled in 30 minutes. A 6pdr can be stripped in 15 minutes and reassembled in 20 minutes. The following components will weigh less than 1000lb each:
    Barrel with breach
    Recoil mechanism and cradle
    Trail
    Axle and wheels
    Shields, platform etc.


    TRACKED BRIDGES.
    Tracked bridges consisted of two steel channels which could be spaced to accommodate the wheels or tracks of vehicles. Originally intended for tanks they were used more widely when they became obsolete in that role.

    Tracked Bridge 12 foot, No3, Class 9.
    These were steel channels with lattice sides and pierced steel decking. There were various patterns weighing between 450lb and 500lb. They could carry trucks, carriers and lorries up to 3ton 4 X 4.

    Tracked Bridge 20 foot.
    Originally intended for tracked vehicle up to Class 24 these were carried and laid by specially fitted 3 ton 6 X 4 lorries. By 1944 it was obsolete in the intended role but could be used for wheeled vehicles when it was Class 12 for four wheeled vehicles and Class 18 for six wheeled vehicles.

    Valentine Bridgelayer. See also Arms/Armour/Armoured Regiment.
    The Valentine Bridgelayer was a Valentine MkII with the turret and ammunition stowage removed and hydraulic equipment installed in the hull. The bridge was Bridge, Tank, 30ft, No1, which was actually 34 foot long and could carry a 30ton load. The bridge was a scissors type which folded in the centre for transport.

    Churchill Bridgelayer. See also Arms/Armour/Armoured Regiment.
    The Churchill Bridgelayer was a Churchill MkII or MkIV with the turret and ammunition stowage removed. Hydraulic equipment was installed in the hull to work the bridge launching gear. The bridge itself was Bridge, Tank, 30ft, No2 which could carry loads up to 60 tons.

    Churchill ARK MkI. See also Arms/Engineers/Assault Engineer Regiment.
    The original Churchill ARK was developed for climbing sea walls and other obstacles on D Day. A Churchill MkII or MkIV had the turret removed and the ring plated over. Timber trackways were fitted above the hull and ramps fitted at both ends, supported by kingposts.

    Churchill ARK MkII. See also Arms/Armour/Armoured Regiment.
    The MkI Churchill Arks were rebuilt to make them more generally useful. The left hand tracks and ramps were widened from 2 foot to 4 foot to allow narrower track vehicles to cross as well as tanks. A square cupola was added.



    RAILWAY BRIDGES

    Military railway bridges did not differ greatly from civilian bridges except that they needed to be built rapidly and there was seldom a great deal of time for planning. They usually replaced a damaged existing bridge and the extent of the damage could not be assessed until the area was secured. Thus the military railway bridge had to be
    - Flexible. The components had to be capable of being adapted to the needs of the moment and the site.
    - Standardised. Personnel needed to be able to construct a bridge without additional training.
    - Rapid to construct. Railway bridges naturally took longer to construct than did the military road bridge but they were needed in a short time to maintain supplies for the armies and for the civilian population.
    - Easy to transport. Railway bridge components could often be transported by rail but this was not guaranteed. Components had to be light enough to be carried on military lorries, and preferably components should be light enough to be manhandled.

    For the campaign in NW Europe railway bridging was of the following types.
    - Rolled Steel Joist (RSJ) and Sectional Joist Equipment. These shared several components and the Sectional Joist Equipment was a more easily transported version of the RSJ equipment. These could be used for spans up to 39 foot.
    - Sectional Welded Plate Girder. This was a heavier equipment capable of constructing spans up to 56 foot. It was not much used since the other equipments were capable of performing the same task, often in combination.
    - Unit Construction Railway Bridge. This could construct spans up to 110 foot. The great majority of railway bridges in NW Europe were built with this equipment, often with RSJ and Sectional Joist Equipment forming approach spans.
    - Sectional Truss Railway Bridge. A heavier equipment capable of building 150 foot spans. This was just coming in to service at the end of the campaign.
    - Light Standard Unit Trestle. This was a flexible system of building supports for bridge spans. The Light equipment was the most widely used.
    - Heavy Standard Unit Trestle. Capable of forming higher or heavier trestles with fewer components and less effort than the Light equipment. Not much used.

    The US Army was happy to standardise on the same bridging material as the British Army and much of the equipment was manufactured in the USA.


    UNIT CONSTRUCTION RAILWAY BRIDGE

    UCRB was a railway bridge design intended to provide spans from 50foot to 85foot. This was later increased to 110foot.

    The largest component of the UCRB was the trough shaped chord member. This was formed from three plates welded together in either fifteen foot or twenty foot lengths. Any span from 30 foot to 85 foot, or later 110 foot, could be constructed by combining the appropriate members. The chord members were fastened together on site using plates bolted through predrilled holes at the end of each member. Vertical members were bolted into the trough of the chord member using predrilled holes. Verticals were at 5 foot intervals. Diagonal bracing was then added to form an N shaped pattern. A trough shaped chord member was then added to the top of the uprights and the truss was then complete. Depth of the truss was 6 foot 10 inches. Width of the truss was 18 inches.

    Usually four trusses were used to support a railway track. Trusses were fastened together in pairs using spacers top and bottom. This gave a three foot spacing. Cross bracing was added at the uprights.

    The heaviest component of the bridge was the 20 foot trough shaped chord which weighed 1 ton.

    The later, and heavier, chord members were painted brown while the earlier members were painted grey.

    COMPONENTS
    The chord member.
    These were the trough shaped components which formed the to and bottom of the truss. They could be 15 foot or 20 foot long and were 18 inches wide. All were predrilled to accept the bolts to hold uprights and sloping members as well as cross bracing and splicing plates.

    Splicing plates.
    Splices were used to fasten chord members together to form longer trusses. The side splicing plates were oblong but with the corners clipped. They were fastened to the chord members using bolts through the predrilled holes. The flange splicing plates used on the top and bottom surfaces were divided so that there was a three inch gap along the centre to allow free passage to the launching rollers.

    Verticals and diagonals.
    All verticals and diagonals were identical and were 6 foot 6 inches long lengths of 10 inch by 8 inch RSJ. These were bolted to the chords using the predrilled holes.

    Bearings.
    Bearings were components on which the completed truss rested. A rocker slab was welded onto a bearing plate which was seated on a bed plate. These could be placed at 11¾ inches, 15 inches or 2 foot 6 inches from the ends of the truss.

    All the above were universal and used in any type of UCRB. The spacers and cross members varied with the type of bridge.

    Spacers
    Cross members.
    Cross members used in a through UCRB were I shaped girders. They were 2 foot 3 inches by 9 inches and were 11 foot 6 inches long. They were positioned at each vertical. Girders were fastened lengthwise on top of the cross members, wooden sleepers were laid across the girders and the rails laid on the sleepers in the usual manner.


    LAUNCHING NOSE
    A launching nose was used when a completed span was being hauled into position. The nose would reach the rollers on the far side of the gap before the centre of gravity was reached and the span fell into the gap.

    The launching nose was of a similar, but lighter construction than the bridge itself. It was of the same overall dimensions so that it could be temporarily fastened to the end of the span. Trusses were T shaped girders with strengthening gussets. The uprights, angles and bracing were all standard UCRB components.

    A Launching nose was 52 foot 6 inches long and came in three sections.
    - The nose section which was 19 foot 3 inches long
    - The centre section which was 14 foot 3inches long
    - The rear section which was 18 foot long



    LAUNCHING.
    The completed bridge span was launched by using hauling and preventer tackles. The hauling tackle was attached to the far bank and used a winch to haul the span across the gap. The preventer tackle was attached to the near bank and acted as both a brake and a means of keeping the nose up.

    Rollers were laid out on the both sides of the gap and the completed span placed on them. The bottom trusses rested on the rollers and where chords were joined with plates there was a gap to allow the rollers an unobstructed path.

    The span was winched out until the launching nose front section just cleared the far side rollers when it was removed. Winching resumed until the mid section just cleared the far side rollers when it too was removed. When the span was in the correct position the rear section was removed and the span was jacked down into position. Usually jacking was assisted by a gantry erected on the bridge trestles. This was removed when the bridge was complete.


    TRESTLES

    LIGHT STANDARD TRESTLE
    The Light Standard Trestle was the most widely used. It was constructed using a number of standard columns of various lengths. These were bolted together to obtain the required height. They were then connected horizontally with struts and braced with diagonal bracing.

    Columns.
    These came in 12 foot (L1), 8 foot (L2), four foot (L3), and 3 foot (L4)lengths. They were constructed from 10 inch by 3 inch rolled steel channels, two such channels being fastened together with 9 inch square plates at 2 foot intervals. Each column had the relevant letter painted on it, L1, L2, L3, L4.

    Each column had a plate at the top and bottom so that they could be bolted together. The plates were 16 inch square and had predrilled holes.

    Struts.
    The horizontal struts were 4 foot 1¾ inches long with 9 inch square plates at each end. They were placed at 4 foot centres, again using predrilled holes.

    Bracing.
    The diagonal bracing was of 2 inch by 2 inch angle iron.

    Grillage joists.
    The joists were used as a footing for the trestle and as a capping to which the bridge trusses could be connected. They consisted of either 10 foot or 15 foot lengths of 12 inch by 6 inch RSJ. They were predrilled to allow columns to be fastened on the flange surface and to accept connecting pieces. The joists themselves could rest on a grillage of timbers or sleepers.

    Connecting pieces.
    These were used to join grillage joists in pairs. The connecting piece was 9½ inches long.

    Camels foot.
    A camels foot was a circular foot which could articulate so as to rest firmly on the ground. It was 3 foot in diameter and had a leg which could be adjusted for length between 3foot 11¼ inches and 5 foot 11¾ inches. This was connected to the bottom of columns and replaced a grillage. It was particularly useful on uneven ground, on existing but damaged piers of bridges or when trestles were to be set on a river bed.


    HEAVY STANDARD TRESTLE
    The Heavy Standard Trestle was much less used than was the Light Standard Trestle. It was a scaled up version using heavier components.

    Columns.
    There were three columns of 14 foot 8 inch (H1), 9 foot 4 inch (H2) and 4 foot (H3). Each was constructed from two 12 inch by 3½ inch RSJ joined by 10 inch by 12 inch plates placed 2 foot 8 inches apart. They were capped by 20 inch square plates. H1, H2 or H3 was painted on the columns.

    Struts.
    These were 5 foot long with 10 square plates at each end.

    Grillage.
    The grillage joists were either 12 foot or 18 foot lengths of 12 inch by 6 inch RSJ with 13 ½ inch distance pieces.

    Camels feet could not be used with the heavy trestle.



    SECTIONAL JOIST EQUIPMENT.

    Sectional Joist Equipment was introduced in order to simplify supply by providing just three lengths of joist which could be used for any span up to 39 foot.

    All the joists were of 24 inch by 7½ inch RSJ and there were three lengths, 9 foot, 12 foot and 15 foot. They were predrilled and could be cut by one foot at either end or both ends so that by combining joists of different lengths and by cutting any length could be obtained in one foot increments.

    Joists were spliced together using splicing plates bolted through predrilled holes.



    SECTIONAL WELDED PLATE GIRDER BRIDGE.

    Sectional Welded Plate Girders were heavier that Sectional Joists and could be used to form longer spans. A plate girder was constructed by welding plates to form an I shape rather than manufactured by rolling.

    The plate girders were 2 foot 11 inches deep and 14 foot long. As supplied the unit was a pair of 14 foot girders welded together in parallel by diaphragms. They were supplied as end units and centre units. The end units incorporated stiffened end posts at one end. A centre unit and two end units were spliced together using splicing plates through pre drilled holes to make a single unit 42 foot long. If required the girders could be cut to give a bridge with a span of 34 foot or 37 foot.

    A bridge span required two trusses. These were normally placed separately either by launching on rollers with a light launching nose, or by using a derrick attached to trestle piers. When both trusses were in position they were connected by steel channel spacers. It was possible to construct a deck bridge or a half through bridge, the decked type being most common.



    EVERALL SECTIONAL TRUSS BRIDGE.

    The Everall Sectional Truss Bridge was developed late in the war and was intended for long spans, up to 400 foot. It was of most use in the immediate post war period when the European railway systems were being rebuilt. The long spans were particularly useful for crossing the navigable rivers of Holland and Germany. Naturally the size, weight and complexity of the bridges meant that they were slow to build, but much quicker than a custom designed bridge for which the components would have to be produced to order.

    There were in fact three type of Everall Sectional Truss.
    Type 15 had girders 15 foot deep and could be used for spans up to 180 foot.
    Type 30 had girders 30 foot deep and could be used for spans up to 330 foot.
    Type 45 had girders 45 foot deep and could be used for spans up to 400 foot.




    RIVER CROSSINGS.
    There is a wealth of contemporary literature on the opposed river crossing. The most generally useful is probably Military Training Pamphlet No. 23. Operations, ‘River Crossings’. This is in fact not a single pamphlet but a series. Part VIII ‘Infantry and Armoured Divisions in the opposed crossing of a water obstacle’ is particularly relevant. There are various editions but that of 1940 is least useful since it predates the extensive use of armoured formations, airborne troops and ground support aircraft.

    There are also handbooks dealing with bridging and rafting equipment in general, and handbooks for each specific equipment.


    An attack will normally involve seven phases:
    Reconnaissance
    Planning
    Preparation and assembly of assaulting troops and bridging equipment.
    Assault
    Exploitation and establishment of bridgeheads
    Construction of the main bridges and the crossing of the main body
    Continuation of the advance and the improvement and maintenance of communications.


    1. RECONNAISSANCE.
    Reconnaissance falls into two stages
    - The collection of general information on which the commander will base his outline plan.
    - The collection of detailed information in accordance with the outline plan.

    In the initial stage air reconnaissance and air photographs are most valuable in providing information about the obstacle and the enemy dispositions. This can be done before the obstacle is reached.

    Leading troops should carry out reconnaissance on as wide a front as possible, both to discover alternative crossing places and to mislead the enemy. It is often possible to carry out reconnaissance on the far bank using reconnaissance boats.

    Engineer reconnaissance is essential. Usually the leading troops will be able to give much information, and provide escorts. Engineer reconnaissance at this stage should include information on:
    - existing bridges, fords, locks, weirs and details of any demolitions carried out by the enemy.
    - the obstacle itself including width, depth, current, nature and slope of banks, islands and sand banks.
    - Any subsidiary obstacles such as tributaries and ditches.

    Reconnaissance parties of units and all arms concerned should visit proposed crossing points and consider:
    - Crossing places for assault troops. These must be suitable for the assaulting infantry and their craft and sufficiently close to bridging sites selected by the engineers. They must also be close to suitable forming up points, be suitable for exploitation and bridgehead defence, provide good observation points for supporting arms and preferably be in an area with minimum enemy resistance.
    - Suitable objectives for the first assault wave. These should not be too far ahead but should provide a defensive position, good observation of the crossing places and provide space for subsequent waves to form up and deploy.
    - Forming up places. Here the assault troops form up for the attack and assault bridging equipment is prepared for launching. The place and its approaches should be protected from observation.
    - Off loading points. These should be behind the forming up point and provide a place for vehicles to be unloaded. Equipment will be manhandled forward to the forming up place so that it should be as close as possible.
    - Fire positions for troops supporting the assault. This will include observation posts.
    - Assembly areas. These should be some five miles to the rear of the obstacle and should have routes that allow rapid access and forward movement.


    2. PLANNING.
    Planning tends to fall into three stages:
    - The plan for the advance to the obstacle and outline plan for the crossing.
    - The detailed plan for the assault, establishment of bridgeheads and construction of bridges.
    - The detailed plan for the crossing of the main body.

    The plan for the advance to the obstacle and outline plan for the crossing.
    The commander will already have an appreciation of the situation from aerial reconnaissance and intelligence reports.

    The Commander Royal Engineers will prepare his appreciation based on
    - Equipment available. This will limit the number and types of bridge that can be constructed.
    - The desirability of rafting. This may speed up the early movement of heavy support weapons and armoured vehicles but delay the construction of bridges.
    - The availability of approaches and exits. The construction of approach roads is very time consuming. The use of sites on or near demolished bridges may ensure good roads but will be known to the enemy.
    - Unloading facilities. There must be facilities for unloading bridging vehicles.
    - Engineer units available.

    Once the number and types of bridges and rafts has been decided and suitable sites selected the commander will make an outline plan. The leading units and reconnaissance parties will be guided by the outline plan and obtain the information required to make the final plan.

    Divisions will make outline plans based on:
    - The composition of leading troops and reconnaissance parties.
    - Special orders to leading troops or airborne troops regarding the seizure of bridges or other points.
    - Outline deception plan.
    - Forward assembly area.
    - Number and type of bridges and rafts to be built.
    - Composition and objectives of forces detailed to establish the bridgehead.
    - Allotment of assault and bridging equipment.
    - Position in the line of march of vehicles carrying bridging equipment.


    The detailed plan for the assault, establishment of bridgeheads and the construction of bridges.
    The timing of the assault is crucial. The assault troops will be very vulnerable and generally need the cover of darkness or smoke. It will rarely be possible to conceal the fact that an assault is to be launched but surprise as to the time and place can be achieved. Preparations must be carried out in secret.

    Timing. A night crossing will favour surprise, and provide cover for the assault force. However darkness will tend to cause delays. Alternatively smoke and supporting fire may provide cover. Ideally the first assault should be timed so as to allow all the attacking force to cross and advance to a point that can be held against counter attack. Light bridges and rafts should be in place to allow essential support weapons to cross. All of this should be complete before first light. On the other hand the first assault should not be so early as to allow the enemy to recover and deploy forces to meet the threat.

    Although darkness is desirable for the assault and for achieving a bridgehead sufficiently large to protect the crossing places from small arms fire, daylight will be required for the continuation of the assault and for the capture of second objectives.

    The detailed plan will be based on:
    - The numbers, types and sites of bridges and rafts, plus the engineer troops detailed for their construction.
    - The bridgeheads to be established.
    - The movement of engineer units and bridging equipment to assembly areas forward of the main divisional assembly area.
    - Arrangements for anti aircraft and anti tank defence.
    - The scale of vehicles which units may take forward of the assembly area before the bridges are complete.
    - The outline traffic control organisation.


    The plan for the crossing of the main body.
    Since the precise time at which bridges will be complete cannot be known, plans may be on a zero basis. This means that the plan, with timings, can be made without the actual start time being decided. When the start time is known this becomes zero hour and all other timings relate to it.

    It is vital that support weapons should be across the obstacle very rapidly in order to give defence against the inevitable counter attack. It is also important that the whole force should be across and united as soon as possible. The worst case scenario is to have the force split and unable to re unite. However speed becomes more difficult to achieve as tanks and anti tank guns become heavier and require heavier bridging and rafting.

    The plan the main body crossing will be based on:
    - The plan for exploitation of the assault.
    - Harbour areas and dispersal points on the far side of the obstacle.
    - Routes and timings for all units.
    - Traffic control arrangements.
    - Arrangements for defence of bridge sites against sabotage
    - Arrangements for the maintenance and improvement of routes, access roads and exit roads.


    Traffic Control.
    To ensure a speedy and orderly crossing efficient traffic control is essential. The organisation needs to provide for:
    - Control of bridging material to the selected forward harbours near bridge sites. The vehicles carrying bridging equipment should have priority on the roads and should be escorted by provost personnel to ensure this.
    - Control of the movement of units from the assembly area over the bridges to ensure that there is no bunching on the approaches or delays in crossing.
    - Control of the movement of units over the bridges in the order that suits tactical requirements. This may change and rapid changes may be necessary.
    - Diversion of traffic from one crossing place to another in case of emergency.
    - Direct units to bridges in accordance with the vehicle and bridge classification and weight limits.
    - Control of returning traffic.

    The traffic control system will cover at least one route forward to each crossing place plus one lateral route on each side of the obstacle. The system will consist of:
    - A regulating headquarters which is best sited at or near advanced divisional headquarters and be operated by a staff officer able to give immediate decisions. Regulating headquarters will have direct communication by line and wireless with sector control. These communications have priority.
    - A sector control for each route. This will control traffic along the one route and crossing. Usually a second sector control will be positioned at the crossing site.
    - Traffic posts will be sited at the junctions of the main routes and laterals on both sides of the obstacle. Communication by line and wireless will be provided between sector control and traffic posts. Traffic posts will be able to divert traffic to an alternative crossing if a bridge is damaged.

    Control extends from the assembly area to the far side traffic post where guides from brigades will lead units to their dispersal point. At actual bridge and ferry sites there should be staff officers, traffic control personnel, engineer officers or NCO’s and officers from the unit moving over the obstacle. Traffic control will regulate the flow and ensure that correct speed and spacing are maintained. Engineer personnel will decide whether a bridge is ready, if it must be closed for repair, what restrictions apply and if individual vehicles exceed the limit. Unit officers will control the movement of the unit and remain until all vehicles have crossed.


    3. ASSEMBLY and PREPARATION.
    The first requirement is for an assembly area. This will be some distance from the obstacle, preferably beyond observation and field artillery fire. Its functions are:
    - To provide harbour areas where divisional engineers will be joined by bridging equipment.
    - To provide harbour areas for MT of units making the assault and support it.
    - To provide an area where re organisation, regrouping and preparation of units detailed for the attack.

    Troops are divided into:
    - Assault force.
    - Supporting troops.
    - Engineer bridging parties.
    - Reserves.
    - Administrative units.

    Assault force.
    The assault force will consist primarily of infantry with such close support weapons as can be manhandled and ferried across in assault craft. Anti tank guns will be required. Engineer detachments must accompany the assaulting infantry to clear mines. Tanks should be included if possible, although these cannot normally cross until a bridgehead has been established. The first wave will be infantry only. Close support may include dismounted carrier platoon, mortars and ant tank guns. These may be able to give support from the near bank before crossing in subsequent waves.

    Assault parties and support parties will move to forming up places.

    Supporting troops.
    These will come from the supporting arms such as artillery, machine gun units or smoke units. Their role is to provide supporting fire for the assault, then for the advance from the far bank to bridgehead positions, and to support the assault troops in case of a counter attack. The supporting force should be deployed before the assault troops move forward from the forming up places. Only essential vehicles should be allowed forward of the assembly area.

    Engineer and bridging parties.
    An advanced engineer party for each bridge or ferry site must be deployed forward close behind the leading assault troops to complete detailed ground reconnaissance of the site, and to start on preparatory work before the arrival of the main bodies of field companies.

    Reserves.
    Reserves should be maintained for exploitation and to deal with unexpected situations. A proportion of engineers and bridging equipment should be included. Reserves should be held well back in the assembly area, from where they can be moved forward as soon as bridges are completed.

    Administrative units.
    Administrative units and unit B echelon transport should be kept well in rear of the assembly area. They can move into the assembly area when the bridges are completed and the crossing of the main body is well advanced. Usually unit B transport will be held in the assembly area until all F groups have crossed.


    Assault Equipment.
    Assault equipment is intended for operation by assault units and not engineers. Some equipment will be already held in the divisional Field Park Company. Additional equipment will be brought forward from the RASC Bridging Company and delivered to the Field Park Company where it will be checked and reloaded. Equipment will then be guided forward by motorcyclists from the Field Park Company to the Brigade Assembly Area. It may then be transported forward to off loading points where it will be un loaded and handed over to infantry sub units who will carry it forward to forming up places. If the off loading points are some distance from forming up points reserve units may be used to carry equipment forward.

    Bridging Equipment.
    Bridging equipment will largely come from RASC Bridging Companies and Engineer Base Dumps. Vehicles carrying this equipment will have priority on roads. In the assembly area the bridging material is handed over to the divisional engineers who will allot it to field companies and reserve. Bridging vehicles will move under divisional control to forward assembly areas. When the time for commencing bridge construction approaches bridging vehicles will move forward to harbour areas near the bridge sites. Here vehicles will be marshalled and called forward a few at a time. Empty vehicles return to the harbour area by another route.


    4. THE ASSAULT.
    Crossing places.
    Apart from the technical considerations listed elsewhere there are three considerations deciding the width of front on which the assault should be launched:
    - It should be on as wide a front as possible so that premature disclosure in one area does not prejudice surprise in another.
    - It must not be so wide as to risk defeat in detail because units are out of supporting range of one another.
    - It must be sufficiently wide to provide a bridgehead large enough to cover the construction of bridges.

    Within units (battalions) crossing places for sub units (companies) must be sufficiently close together to make co operation between parties possible soon after crossing. Crossing points should be concentrated so that a commander can rapidly gain control on the far bank. Individual boats must cross from and too the same points on each trip to avoid sub units becoming mixed.

    A beachmaster should be appointed for each crossing place. He should control the crossing of second and subsequent waves. He will remain on the near bank.

    Objectives.
    There are three successive objectives:
    - A position which will eliminate effective small arms fire against the crossing sites.
    - A position which will eliminate ground observation of artillery fire on the bridge sites while allowing artillery fire support from the near side of the river.
    - A position which will eliminate all artillery fire on the bridge site and provide the space for the main body to manoeuvre on the far side.

    In all cases the attack should aim at going forward as rapidly and as deep as possible. Only in extreme circumstances should the initial waves halt and wait for succeeding waves.

    Supporting and covering fire.
    It may be decided that an assault will be attempted without fire support, especially at night, in order to achieve surprise. Fire support should however be available at short notice if surprise should fail. If fire support is required it should be opened on centres of resistance shortly before the assault is launched. Infantry weapons giving covering fire should be sited near to the crossing places so that they can watch the progress of the assault. Covering fire should be at its maximum as the leading section launch their craft. In daylight smoke fired by artillery and mortars will be very effective.

    Engineers in the assault.
    Except in very difficult conditions the infantry must operate assault equipment without engineer assistance. Parties of engineers should follow closely behind assault troops in order that work on rafts and bridges may start as soon as a bridgehead has been established.


    5. THE ESTABLISHMENT OF BRIDGEHEADS.
    Speed is essential. Assaulting troops must be established before the enemy can launch his counter attack. Once the far bank has been reached and sub units have reformed, they should move forward to their objectives. Some troops should have been detailed to clear the far bank of troops in the vicinity of the crossing places, and arrangements made to gain touch with troops at adjacent crossing places.

    As soon as any troops are established on the far bank they must be reinforced by all available reserves to enlarge the bridgehead. Brigade headquarters must be well forward to ensure that reserves can be rapidly diverted to meet changes in the tactical situation. Infantry close support weapons must be ferried as soon as possible without waiting for the construction of bridges or heavy rafts. Anti tank guns in particular must be got across early.

    Artillery support will be required by assaulting troops. Guns must be sited well forward and Forward Observation Officers should cross with the early waves. Counter battery fire may be required especially if enemy artillery threatens the bridge sites. Air observation should be available. Tactical air support will be useful against targets beyond artillery range, in particular enemy reserves preparing to counter attack.

    Before work is started on bridges and heavy rafts every effort should be made to reach the second objectives. As soon as possible the third objectives should be reached to protect the crossing sites form enemy artillery.

    At each bridge site an officer should be appointed to be responsible for local defence. He will not be an engineer officer and will be able to call upon any troops in the vicinity to assist. Troops must remain in position until a sufficient force has crossed to remove the danger of counter attack. Some local defence will be required against sabotage and attack by airborne troops.



    6. CONSTRUCTION OF BRIDGES AND CROSSING OF THE MAIN BODY.
    It will generally be easier to build a bridge on the site of a demolished one. Not only will there be good foundations but there will be good approach roads and exit roads. Construction of approaches and exits can be more time consuming than building the bridge and may require pioneer or infantry as labour. Reserves of manpower and equipment should be provided in order to maintain the approach and exit roads, and to repair damage to the bridge.

    It may be possible to start preliminary work on a bridge site before bridgeheads are established. It may even be possible to carry out some work before the assault is launched. The construction of the bridge should start as soon as the bridgehead is secure.

    The bridging plan may include both light and heavy bridges. Light bridges will be completed more rapidly and will allow most of the transport to cross. However heavy bridges will be required for tanks and other armoured vehicles and the construction of light bridges should not delay the construction of heavy ones.

    A striking force of units not involved in the assault and the establishment of bridgeheads should be organised in the assembly area. If an enemy is retreating this force should cross bridges first so as to carry out a pursuit. This should take priority over all but the most essential vehicles for the assault force. In any case as soon as the bridge is complete the divisional headquarters must be informed and the traffic control organisation should order units forward. If there are light and heavy bridges it must be decided whether it is better to pass entire units over the bridge or to divide it into light and heavy vehicles.

    The capacity of a military bridge is unlikely to exceed 100 vehicles per hour allowing for speed restrictions and spacing. Over prolonged periods 60 vehicles per hour is more reasonable to allow for interruptions and maintenance.

    Arrangements must be made to replace bridging equipment in the divisional field parks. Infantry should salvage the assault equipment that they used and deliver it to the engineers at a pre arranged rendezvous.

    Eventually some of the bridges will be replaced by more permanent bridges with more permanent roads. There will also be a need for heavier bridges to take loaded tank transporters and other heavy loads. Each corps requires a Class 80 bridge. Line of Communication engineers will build both road and rail bridges to carry the supplies for the army.


    AN EXAMPLE.
    THE RHINE CROSSING. (OPERATION PLUNDER).

    Preparation for an assault crossing of the Rhine started many months in advance since it was clear that eventually this major obstacle would have to be tackled. Of course there was the possibility that Germany would surrender before the Rhine was reached.

    Twice it seemed that it might be possible to avoid an assault crossing by seizing bridges. The bold airborne action to seize bridges, including the major Rhine crossing at Arnhem, nearly succeeded. Later US forced did seize the bridge at Remagen when the Germans failed to demolish it, but it collapsed soon afterwards.

    Montgomery was determined that this crossing was to be a text book set piece assault, planned in the greatest detail. This was what he was best at. The assault would take place along a 15 mile stretch of the lower Rhine. This area was a wide, level flood plain and the river had high dykes to prevent flooding. The main advantage was that the river was slow moving at this point.

    The right wing of the assault was entrusted to the US 9th Army, which was placed under command of 21 Army Group for the operation. The British assault was to be carried out by XII Corps on the right and XXX Corps on the left. II Canadian Corps was holding the left flank but would not take part in the assault, although 3 Canadian Division would do so under command of XXX Corps.

    The assault divisions were 15 Division of XII Corps and 51 Division of XXX Corps plus 1 Commando Brigade on the right. The Commandos would hold the town of Wesel, with its important road junctions, until relieved by airborne forces.

    H Hour was 2200 on 23rd March.

    51 Division Assault.
    Two battalions of 154 Brigade and two battalions of 153 Brigade launched the assault in Buffaloes. They crossed the river in 2 ½ minutes and the third battalions crossed as soon as the Buffaloes returned. 3.7” howitzers of 454 Mountain Battery RA landed with the leading troops and gave close support. Just before midnight two battalions of 152 Brigade crossed in stormboats while the third battalion was held in reserve until dawn when it crossed is such stormboats as had returned.

    1 Commando Brigade Assault.
    The Commando Brigade launched their assault at the opposite end of the British front at the same time as 51 Division launched theirs. 46 Royal Marine Commando crossed in Buffaloes of 77 Assault Squadron RE, followed by 6 Commando in stormboats. As soon as possible the Buffaloes returned to ferry 45 Royal Marine Commando and 3 Commando.

    15 Division Assault.
    With troops established on both flanks the assault on the centre was launched by 15 Division at 0200 hours. 44 Brigade and 227 Brigade each deployed two battalions, each with assault troops in Buffaloes and a follow up in stormboats. Soon 46 Brigade was ferried across also.

    The Rhine was considered too wide and too fast flowing to allow the use of assault boats manned by infantry. Buffaloes were used for the assault waves. Stormboats manned by engineers and powered by outboard motors were used instead. Buffaloes also replaced the lighter rafts since they could carry light weapons, 6pdr anti tank guns, jeeps, 3.7” howitzers and carriers. Some were converted to carry 17pdr anti tank guns. Stormboats could also carry jeeps and 6pdr anti tank guns.

    Once the assault force and close support weapons were across the river Buffaloes and stormboats ran a ferry service while the raft ferries were constructed.


    Xanten on XII Corps front was an ideal bridging point for access and exit. The first bridges were completed here since the site was safe from enemy interference. The following were constructed.
    - Draghunt Bridge. A Class 9 Folding Boat Equipment Bridge. Built by XIII Corps Troops Engineers. 1,440 foot long. Construction started 13.00 hours on 24 March, having being delayed by enemy action. It was completed in ten hours because the component rafts had been assembled earlier. This was the first bridge to open.
    - Sussex Bridge. A Class 12 tactical Bailey Pontoon Bridge. Built by XII Corps Troops Engineers. 1,940 foot long it was in fact two bridges with the second, 360 foot, part crossing a secondary obstacle. Construction started at 08.00 on 24 March. Completed 10.00 on 25 March. This was to carry support trops and then wheeled transport.
    - Digger Bridge. A Class 40 tactical Bailey Pontoon Bridge. Built by 7 Army Troops Engineers. 1,091 foot long. Construction started at 09.30 on 24 March. Completed 16.00 on 25 March.
    - Sparrow Bridge. A Class 40 all weather Bailey Pontoon Bridge. Built by 15 GHQ Troops Engineers. 1,713 foot long. Construction started on the morning of 27 March and took six days to complete. It was a more permanent bridge which replaced the previous two. It was later extended by an approach bridge and approach road to speed the passage of traffic. Although still Class 40 vehicles were not so restricted by speed and spacing as on the tactical bridges.

    Rees was the bridging point on XXX Corps front and again had good road communications. Bridge building was delayed by enemy action. The following were constructed.
    - Waterloo Bridge. A Class 9 Folding Boat Equipment Bridge. Built by 18 GHQ Troops Engineers. 1,300 foot long. Construction started under the cover of smoke at 08.00 on 25 March. Completed 02.00 on 26 March.
    - Lambeth Bridge. A Class 15 tactical Bailey Pontoon Bridge. Built by XXX Corps Troops Engineers. 1,206 foot long. Construction started early on 25 March. Completed early on 26 March.
    - London Bridge. A Class 40 Bailey Pontoon Bridge. Built by 8 GHQ Troops Engineers. 1,174 foot long. Construction started at 17.00 on 25 March. Completed 23.00 on 26 March.
    - Blackfriars Bridge. A Class 40 Bailey Pontoon Bridge. Built by 2 Canadian Corps Engineers. 1,764 foot long. Construction started at 10.00 on 26 March. Completed at mid day on 28 March.
    - Westminster Bridge. A Class 40 all weather Bailey Pontoon Bridge. Built by 6 Army Troops Engineers. 1,402 foot long. Construction started at 11.00 on 26 March. Completed 18.00 on 29 March. This bridge had to cater for a wide range of river level. This was the last of the bridges constructed for the assault and it was officially opened by General Dempsey, GOC 2 Army, in the presence of detachments from all engineer units involved in the crossing.

    Emmerich was outside the assault area but a bridge was constructed by and for the Canadian Army. This was the Maclean Bridge. It was a Class 40 all weather Bailey Pontoon Bridge, 1,656 foot long. Construction started on 2 April 1945.

    British troops also had the use of bridges built by 9 US Army which was at the time part of 21 Army Group.



    RAILWAYS LOCOMOTIVES and ROLLING STOCK
    The army relied on railways to move the large quantities of stores and supplies required. In France and the Low Countries the railway was not only needed to supply the Allied Armies but also to supply the liberated countries. Before the railways could operate there was much reconstruction needed. In France and the Low Countries the railways had been systematically destroyed by air attack and sabotage by the Allies. Further more the Germans had removed much of the rolling stock and most of the locomotives, as well as destroying many remaining bridges. What remained in the way of locomotives, rolling stock and railway engineering work was largely unserviceable.

    The task of the Royal Engineers was firstly to rebuild the railways and their bridges and then to operate the railway system. When the railways were rebuilt the operation of them fell to the British Transport Service and the US 2nd Military Railroad Service

    The British Army operated railway systems in France in 1939/1940, and much of the rolling stock and most of the locomotives were lost when France fell and the British were evacuated. The British Army then acquired many locomotives for operations in many theatres of war. It was always known that one day France would be invaded and the Germans driven out, but it was not until July 1942 that planning for the invasion of Europe gave a high priority to producing new locomotives.

    It was decided that there would be a need for two main types of locomotive
    - a main line freight locomotive
    - a heavy shunting locomotive.

    Both the British and the USA designed and produced locomotives in these classes as well as lighter locomotives for use in dumps and depots.

    The British designs were
    - the 2-8-0 Austerity freight locomotive
    - the 2-10-0 Austerity which had a lighter axle loading
    - the 0-6-0 saddle tank Austerity shunting locomotive

    These were all needed in a reasonably short time. The date of the invasion was not known but the longest period of time was thought to be two years, while some were still pressing for an invasion in 1943. In order to produce the locomotives the North British Locomotive Company gave up tank production and reverted to locomotive production. The Vulcan Foundry Company partly gave up tank production to concentrate on locomotives. Between them these two companies would produce nearly 1200 Austerity locomotives.

    The Hunslet Forge Company gave up armament work to produce the required shunters.

    The specification for the freight locomotives called for a locomotive capable of hauling 1000 tons at 40mph, and to be able to work in all conditions for a period of two years. Time did not allow for a completely new design, but neither time nor materials allowed for the building of traditional locomotives. A compromise was arrived at where an existing design would be adapted for speedy and economical production. The War department already used considerable numbers of LMS 8F 2-8-0 locomotives and this was used as a basis for the new design. The Austerity had a definite resemblance to the 8F although almost every part was modified in order to speed production, to save scarce materials and to avoid the use of casting and skilled labour.


    WAR DEPARTMENT ‘AUSTERITY’ 2-8-0

    Eventually 935 Austerity 2-8-0 locomotives were built with the WD numbers
    - 800 to 875
    - 7000 to 7509
    - 8510 to 8718
    - 9177 to 9312

    As the locomotives were built well before they were needed they were loaned to civilian operators to help with the huge amount of military rail traffic that they were carrying in the UK. In all 450 were loaned as follows
    - LNER 350 locomotives
    - LMS 50 locomotives
    - SR 50 locomotives

    Six locomotives were used by the War Department at Faslane, Longmoor, Cairn Ryan and Melbourne. The rest went into store at Longmoor and Melbourne.

    The Austerity 2-8-0s went to Europe starting in September 1944. All except three were sent. One was used at Longmoor (9250) while the other two were used at Faslane and Cairn Ryan (7223 and 7369), changing their location for some reason.

    In the spring of 1945 222 Austerity 2-8-0 were loaned to the USA/TC when they had the following added to the tender ‘TRANSPORTATION CORP USA’


    NOTE:
    The military railways mentioned in the text are
    - Longmoor in Hampshire. This was the main Royal Engineers railway depot for training, storage and maintenance. It had a circular training track and other facilities.
    - Melbourne in Derbyshire. This was a smaller training depot in the North of England.
    - Faslane and Cairn Ryan. These were Military Ports which were built in Scotland. They were each capable of berthing six cargo ships and were built out of the range of enemy aircraft and in a convenient location for N America. Military railways connected the ports to the civilian rail network. Faslane was Military Port No1 and Cairn Ryan was Military Port No 2.


    WAR DEPARTMENT ‘AUSTERITY’ 2-10-0

    150 Austerity 2-10-0 were built. First deliveries were in December 1943 and 79 were loaned to the LMS until they were needed for service in Europe. These were returned between August and November.

    Not all the Austerity 2-10-0s went to Europe.
    - 17 went to the Middle East where their light axle loading was an asset
    - 7 stayed at Longmoor, one working and six in store
    - 20 were loaned to the LNER
    - 24 were sent to Europe after fighting had ceased, arriving in May and June 1945.

    The following locomotives arrived in Europe between September and December 1944
    September 3670, 3680, 3706, 3724, 3668, 3693, 3707, 3708, 3709, 3711, 3712, 3713, 3725, 3730
    October 3650, 3661, 3666, 3667, 3671, 3673, 3676, 3679, 3681, 3689, 3690, 3692, 3694, 3699, 3700, 3701,
    3703, 3704, 3705, 3710, 3714, 3715, 3716, 3717, 3719, 3721, 3723, 3726, 3727, 3728, 3732, 3741,
    3742, 3675
    November 3663, 3665, 3691, 3698, 3702, 3718, 3720, 3722, 3729, 3734, 3735, 3738, 3740, 3743, 3744, 3745,
    3746, 3747, 3748, 3749
    December 3662, 3664, 3669, 3695, 3696, 3697, 3731, 3733, 3736, 3749


    WAR DEPARTMENT ‘AUSTERITY’ 0-6-0ST

    377 WD 0-6-0ST were built, although some were not completed until after the war. Only 90 went to the Continent although a further 24 went in May 1945 and 50 went to Belgium for the civilian operator SNCB.

    November 5004, 5005, 5008, 5009, 5010, 5013, 5014, 5015, 5016, 5018, 5022, 5025, 5051, 5052, 5057, 5058,
    5059, 5065, 5085
    December 1489, 1490, 1491, 1496, 5001, 5007, 5012, 5020, 5021, 5023, 5024, 5050, 5055, 5057, 5074, 5081,
    5086, 5088, 5123, 5127, 5128, 5130, 5131, 5132, 5155, 5157, 5159, 5160, 5196, 5197, 5198, 5199
    January 5000, 5002, 5003, 5011, 5026, 5082
    February 5053, 5054, 5066, 5080, 5098, 5104, 5105, 5106, 5115, 5136


    WAR DEPARTMENT 0-6-0 DIESEL SHUNTER

    A number of diesel locomotives of LMS design had been purchased by the War Department but by 1942 requirements had been met. In 1943 it was decided that more were needed for the Invasion of Europe and a small number were ordered to an improved LMS design. These were 350hp shunters.

    The first four locomotives were delivered before they were needed and were sent to Longmoor before going to France
    November 262 and 263
    December 260 and 261
    The rest went direct to France as they were completed
    January/February 264,265, 266, 267, 268
    April 269
    May 270
    The last three were too late for the war and went to Longmoor.




    WAR DEPARTMENT 0-4-0 DIESEL SHUNTER

    These were small 150hp shunters intended for use in military depots and dumps.

    They were completed in 1942 and 1943 and went to work in various depots and dumps in the UK. Five went to the Middle East and the remaining 15 were concentrated at Longmoor in early 1944 in preparation for the invasion. Some were used for practice and training in loading them onto Federal 504 transporters and 40 ton Orolo tracked recovery trailers.

    The first four locomotives were landed over the beaches in June. They were carried ashore on Orolo tracked trailers towed by Caterpillar D8 tractors. These worked on transporting supplies from the beach area to the dumps and depots of Normandy.
    June 29, 30, 32, 33
    September 31, 39,40,41,42,43,44,45,46,47,48 were landed from normal cargo ships at Cherbourg and again used a dumps and depots in Normandy.
     
    Last edited by a moderator: Jul 2, 2017
  2. Trux

    Trux 21 AG Patron

    BRIDGE and ENGINEER EQUIPMENT ILLUSTRATIONS

    photographs of Trux Models bridging equipment.

    bridge1.jpg
    A class 40 Bailey Pontoon Bridge using MkV pontoons.

    bridge3.png
    Class 50 Raft.
    bridge2.png
     
    Last edited by a moderator: Jul 2, 2017
    leccy and stolpi like this.
  3. JohnS

    JohnS Senior Member

    Nice models.
     
  4. Roy Martin

    Roy Martin Senior Member Patron

    Have skimmed through Trux's comprehensive coverage of bridging equipment. Elsewhere I have come across two references of shipping 'Bridge boats' from Karachi to the PG in one case and 180 of them to Calcutta in the other (1942/3). Would these be Bailey pontoons?
     
  5. Trux

    Trux 21 AG Patron

    Roy.
    Not very likely. Bailey equipment did not arrive in the Far East until much later. The earlier MkV pontoons were available in limited numbers earlier. Most likely would be the locally made PN Boat which was general similar in design. Built from locally sourced timber sawn into planks they were 16 foot long with a square stern and sloping bow. Two could be fastened together to make a pier. This could have a timber roadway. The rather poor pictures I have seen are more like a MkV pontoon bridge in appearance but with a lower weight limit.

    Not much information available when I last looked but that was some years ago.

    Mike
     
  6. Roy Martin

    Roy Martin Senior Member Patron

    Mike,
    Thanks. I was imagining something bigger as the ship was selected for her 60' long hatches, anyway that puts that one to bed.
    Roy
     
  7. Trux

    Trux 21 AG Patron

    Bailey pontoons are only 20 foot long.

    Mike
     
  8. Roy Martin

    Roy Martin Senior Member Patron

    Thanks Mike, noted.
    Roy
     

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