Category:Suspension bridges

Alcon suspension bridge model [image info]

1878: Clifton Suspension Bridge, courtesy of WikiMedia [image info]

1872: The Brooklyn Bridge [image info]

Tri-ang Railways R264 Grand Victorian Suspension Bridge [image info]

A suspension bridge has its roadway suspended from some other structure, this other structure being easier to build, but the wrong shape for carrying a flat horizontal roadway directly.

The predecessor of the modern "industrial" suspension bridge would arguably have been the rope suspension bridges traditionally used in some remote areas to cross deep chasms. "Modern", "industrial" suspension bridges appeared in the early 1800 thanks to developments in industrial metalworking. As a field of engineering, the subject moved forward with the invention of industrial metal chain (used to build the old Chain Pier in Brighton), and then, again, with the invention of string steel cabling.

Modern types:

A classic suspension bridge typically consists of two or more heavy towers, with metal chains or steel cables strung between them, with vertical cables, chains or rods hanging down to the level of the roadway.
A cable stay bridge have the roadway suspended from cables connected directly to the towers, creating a spaly of angles. This design does away with the separate suspension chain or cable, but become less effective for longer spans.
Some bridges combine both methods.

The Sydney Harbour Bridge has a heavy arch linking the bases of a pair of towers. Although the large arch is a bridge in its own right (it allows access on foot for servicing), the roadway is suspended form it, making it a suspension bridge.
The Tower Bridge central section is a hinged counterweighted bascule bridge, but the bridge sections leading to the two towers are suspension bridges.
Brighton's defunct Chain Pier was essentially a chain suspension bridge linking the seafront with a boat-landing stage.