Pontoon bridges
U.S. Army troops cross the Rhine on a heavy pontoon bridge, March, 1945
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| Carries | Pedestrian, automobile, truck |
|---|---|
| Span range | Short to long |
| Material | Various: steel, concrete, boats, barrels, plastic floats, appropriate decking material |
| Movable | Generally not, but may have movable sections for watercraft passage |
| Design effort | low |
| Falsework required | No |
A pontoon bridge (or ponton bridge), also known as a floating bridge, uses floats or shallow-draft boats to support a continuous deck for pedestrian and vehicle travel. The buoyancy of the supports limits the maximum load they can carry.
Most pontoon bridges are temporary, used in wartime and civil emergencies. Permanent floating bridges are useful for sheltered water-crossings where it is not considered economically feasible to suspend a bridge from anchored piers. Such bridges can require a section that is elevated, or can be raised or removed, to allow waterborne traffic to pass.
Pontoon bridges have been in use since ancient times and have been used to great advantage in many battles throughout history, among them the Battle of Garigliano, the Battle of Oudenarde, the crossing of the Rhine during World War II, and during the Iran–Iraq War Operation Dawn 8.
A pontoon bridge is a collection of specialized, shallow draft boats or floats, connected together to cross a river or canal, with a track or deck attached on top. The water buoyancy supports the boats, limiting the maximum load to the total and point buoyancy of the pontoons or boats. The supporting boats or floats can be open or closed, temporary or permanent in installation, and made of rubber, metal, wood, or concrete. The decking may be temporary or permanent, and constructed out of wood, modular metal, or asphalt or concrete over a metal frame.
The spelling "ponton" in English dates from at least 1870. The use continued in references found in U.S. patents during the 1890s. It continued to be spelled in that fashion through World War II, when temporary floating bridges were used extensively throughout the European theatre. U.S. combat engineers commonly pronounced the word "ponton" rather than "pontoon" and U.S. military manuals spelled it using a single 'o'. The original word was derived from Old French ponton, from Latin ponto ("ferryboat"), from pons ("bridge").
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