Types of suspension bridges

A suspension bridge supports its structural load with cables, ropes, or chains anchored at each end. Cables on the earliest suspension bridges were anchored in the ground; some modern suspension bridges anchor the cables to the ends of the bridge itself. Earliest suspension bridges had no towers or piers but the majority of larger modern suspension bridges have them. All of the 14 longest bridges in the world are suspension bridges.

Types
Types of suspension bridge include:

A pure suspension bridge is one without additional stay cables and in which the main cables are anchored in the ground. This includes most simple suspension bridges and suspended-deck suspension bridges, and excludes self-anchored suspension bridges.

Hybrid types
Some suspension bridges are of unusual hybrid types. Among these are suspension bridges that have an "intermediate deck". These bridges have a portion of deck that resembles an underspanned suspension bridge. Some of the earliest suspended-deck suspension bridges were of this type, and they continue to be constructed. Examples constructed in the 20th century include a viaduct over the river Oberargen near Wangen, Germany. A 258 m span of the viaduct has a cable support below the deck, with one end of the cable anchored at a pier and the other end tied into a conventional cable stay. The underspanned portion of the span is 172 m long and has three vertical members.

The Akashi Kaikyō Bridge, one of the longest suspension bridges in the world, is a suspended-deck suspension bridge with a stiff truss girder deck. Its main span is 1991 metres long.

Construction
Unlike other types of bridge, suspension bridges can usually be built without use of falsework or even any access from below the bridge. In many cases, the main cables are constructed first, often with a pilot cable. Construction then proceeds by hanging components and equipment from the main cables. The articles about each type of bridge have further specific construction details.

Suspension bridges are suitable for the longest spans, provided the cables and their anchorage are of sufficient strength. Their construction cost is high, so usually they are less economical than other bridges for spans less than 1000 feet. However, shorter spans have been constructed for aesthetic reasons.

All types of suspension bridges have less rigidity than other bridges. Because of their greater flexibility, these bridges are more suitable as road bridges than railroad bridges.