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(36 t). This could be of any length, and was what was used over major river obstacles such

as the Rhine and Moselle. Doctrine stated that it would take 5 1/2 hours to place a 362-foot
section of M2 tread way during daylight and 7 1/2 hours at night. Pergrin says that in

practise 50 ft/hour of tread way construction was expected, which is a little slower than the
speed specified by doctrine.

By 1943, combat engineers faced the need for bridges to bear weights of 35 tons or more.
To increase weight bearing capacity, they used bigger floats to add buoyancy. This

overcame the capacity limitation, but the larger floats were both more difficult to transport
to the crossing site and requiring more and larger trucks in the divisional and corps trains.

3.9. BRITAIN

Donald Bailey invented the Bailey bridge, which was made up of modular, pre-fabricated
steel trusses capable of carrying up to 40 short tons (36 t) over spans up to 180 feet (55 m).

While typically constructed point-to-point over piers, they could be supported by pontoons

as well.

The Bailey bridge was used for the first time in 1942. The first version put into service was

a Bailey Pontoon and Raft with a 30 feet (9.1 m) single-single Bailey bay supported on two
pontoons. A key feature of the Bailey Pontoon was the use of a single span from the bank

to the bridge level which eliminated the need for bridge trestles.

For lighter vehicle bridges the Folding Boat Equipment could be used and the Kapok

Assault Bridge was available for infantry.

An open sea type of pontoon, another British war time invention, known by their code
names, the Mulberry harbours floated across the English Channel to provide harbours for

the June 1944 allied invasion of Normandy. The dock piers were code named "Whale".

These piers were the floating roadways that connected the "Spud" pier heads to the land.
These pier heads or landing wharves, at which ships were unloaded each consisted of a

pontoon with four legs that rested on the sea bed to anchor the pontoon, yet allowed it to

float up and down freely with the tide. "Beetles" were pontoons that supported the "Whale"
piers. They were moored in position using wires attached to "Kite" anchors which were

also designed by Allan Beckett. These anchors had a high holding power as was
demonstrated in D+13 Normandy storm where the British Mulberry survived most of the

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