Suspension bridges

Advantages:

• Can cover very long spans;

• The steel cable used is cheaper than steel girders.

Disadvantages:

• A very flexible bridge, so not used for railways. As trains are heavier than cars or lorries, their weight is less spread out across the bridge.

The photograph shows the Humber Bridge, Humberside. It was opened in 1981, and had the longest, single span in the world. The main span is 1,410 metres, the total length of the bridge is 2,220 metres. A longer bridge has now been constructed at at Akashi-Kaikyo, in Japan. Its overall length is 3,910 metres, with the longest span being 1,990 Metres.

The earliest suspension bridges were built in the 19th century, designed by engineers such as Stevenson and Brunel. This design is a common design for modern bridges which need a long span, though most of the latest are cable stay bridges.

Bridge index.

Forces in bridges.