What is Pontoon bridge?
{{infobox bridge type | image = US Army crossing the Rhine on heavy ponton bridge at Worms, March, 1945.png | image_title = U.S. Army troops cross the Rhine on a heavy pontoon bridge, March 1945<ref>Beck, Alfred M., et al., [http://www.history.army.mil/html/books/010/10-22/CMH_Pub_10-22.pdf ''The Corps of Engineers: The War Against Germany''], Center of Military History (U.S. Army), 1985. The bridge was built by the 85th Engineer Heavy Combat Battalion on March 26, 1945, 200 feet downstream from the demolished Ernst Ludwig highway bridge. It was named the Alexander Patch Bridge after the Seventh Army commander, General [[Alexander Patch]]. A stone tower of the former bridge is visible on the opposite bank.</ref> | sibling_names = | descendent_names = | ancestor_names = | 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 = low | falsework = No }} A '''pontoon bridge''' is a [[bridge]] that floats on water. It is a '''floating bridge''' with barges or boats ('pontoons') to support the bridge deck. Pontoon bridges are usually temporary structures, but some are used for long periods. Permanent floating bridges are useful for sheltered (quiet) water-crossings. It may be too [[wikt:expensive|expensive]] to suspend a bridge from anchored [[pier]]s. Pontoon bridges may need a section that is elevated, or can be raised or removed, to allow [[ship]]s to pass. Pontoon bridges are often used in [[war]]time as [[river]] crossings. They are usually temporary, and are sometimes destroyed after crossing (to keep the enemy from using them), or collapsed and carried (if on a long march). They were used to great advantage in many [[battle]]s. Pontoon bridges have been in use since ancient times. It is thought that the first [[London Bridge]] was a [[Ancie