A pontoon bridge or floating bridge or bridge of boats is a bridge that floats on water and in which barge- or boat-like pontoons support the bridge deck and its dynamic loads. While pontoon bridges are usually temporary structures, some are used for long periods of time. 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 ships to pass.Pontoon bridges are especially useful in wartime as river crossings. Such bridges are usually temporary, and are sometimes destroyed after crossing, or collapsed and carried. They were used to great advantage in many battles throughout time, including the Battle of Garigliano, the Battle of Oudenarde, and many others.Pontoon bridges have been in use since ancient times.In ancient China, the Zhou Dynasty Chinese text of the Shi Jing records that King Wen of Zhou was the first to create a pontoon bridge in the 11th century BC. However, the historian Joseph Needham has pointed out that in all likely scenarios, the temporary pontoon bridge was invented during the 9th or 8th century BC in China, as this part was perhaps a later addition to the book. Although earlier temporary pontoon bridges had been made in China, the first secure and permanent ones in China came first during the Qin Dynasty. The later Song Dynasty.Chinese statesman Cao Cheng once wrote of early pontoon bridges in China.