In 1000 B.C.E. it was recorded that King Wen of the Zhou Dynasty, ancient China, designed the first pontoon bridge. The invention was to be incorporated into his elaborate wedding ceremony, allowing the wedding procession to cross the Weihe River.
King Wen's design was of a floating bamboo deck structure supported by boatlike pontoons to allow a water crossing. Since their invention, the floating bridges have become much more than just a decorative water crossing—they have become a military weapon. One of the earliest recorded pontoon bridges to be used in combat was built in 974 C.E. by the Song Army of ancient China, who constructed it in fewer than three days. However, such bridges take a lot less time to destroy or dismantle—a necessary practice to prevent the enemy from following,
King Wen's design is still being used by the military to this day. In 2003 the U.S. Army's "Assault F-loat Ribbon Bridge" was used to cross the Euphrates River near Al Musayib during "Operation Iraqi Freedom."
Not all pontoon bridges are temporary structures. Some are established across rivers where it is uneconomical to build a suspension bridge. These bridges include an elevated section to allow boats to pass. One of the longest of these bridges spans Lake Washington in Washington State; the Lacey V. Murrow Memorial Bridge, 6,620 feet (2,019 m) in length, was completed in 1940 and cost $10 million less than an orthodox bridge to build.
Cheap though they are, pontoon bridges are not particularly safe. They are especially vulnerable to bad weather and have been known to be destroyed by strong winds. In fact, part of the Lacey V. Murrow Memorial Bridge sank in 1990 after a heavy storm and was subsequently rebuilt.