Definition of Suspension bridges

This article is concerned with a particular type of suspension bridge, the suspended-deck type. For an index to the several types see suspension bridge types.

A suspension bridge is a type of bridge that has been created since ancient times as early as 100 AD.  Simple suspension bridges, for use by pedestrians and livestock, are still constructed, based upon the ancient Inca rope bridge. One of the oldest of engineering forms, suspension bridges were constructed by primitive peoples using vines for cables and mounting the roadway directly on the cables. A much stronger type was introduced in India about the 4th century AD that used cables of plaited bamboo and later of iron chain. Suspended well from two high locations over a river or canyon, simple suspension bridges follow a shallow downward arc and are not suited for modern roads and railroads. Advances in materials and design led to the development of the suspended-deck suspension bridge, a modern bridge capable of carrying vehicles and light rail. Instead of the deck following the downward arc of the main load-bearing cables (or chains), these cables are suspended between towers, and vertical suspender cables carry the weight of the deck below, upon which traffic crosses. This arrangement allows the deck to be level or to arc slightly upward for additional clearance.