pontoon

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. There are permanent pontoon bridges in civilian use, carrying highway traffic and allowing ships or boats to pass on the river or lake being crossed. 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.

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