pontoon bridge

A pontoon bridge (or ponton bridge), also known as a floating bridge, is a bridge that 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 that they can carry.

Most pontoon bridges are temporary and used in wartime and civil emergencies. There are permanent pontoon bridges in civilian use that can carry highway traffic; generally, the relatively high potential for collapse and sinking (e.g. due to waves and collisions) and high continuous maintenance costs makes pontoons unattractive for most civilian construction. Permanent floating bridges are useful for sheltered water crossings if it is not considered economically feasible to suspend a bridge from anchored piers (such as in deep water). Such bridges can require a section that is elevated or can be raised or removed to allow waterborne traffic to pass. Notable permanent pontoon bridges include the Evergreen Point Floating Bridge, Hood Canal Bridge, and the Nordhordland Bridge.