Suspension bridge

A suspension bridge is a type of bridge that has been made since ancient times. Simple suspension bridges, for use by pedestrians, are still constructed in some places worldwide for use by pedestrians and livestock using designs based upon the ancient Inca rope bridge. Suspended 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. Over the centuries, advancements 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 a downward arc of the main load bearing cables (or chains) these cables are suspended between towers and the cables support vertical suspender cables to carry the weight of a deck below, upon which the traffic crosses. This arrangement allows the deck to be level or to arc slightly upward for additional clearance.

Other famous suspension bridges

• Union Bridge (England/Scotland) 137 m - 1820. The oldest in the world.
• Menai Suspension Bridge (north Wales) 176 m - 1826
• Conwy Suspension Bridge (north Wales) 1826
• Wheeling Suspension Bridge (USA) 308 m - 1849. The largest suspension bridge from 1849 until 1883
• Clifton Suspension Bridge (England) 214 m - 1864
• Brooklyn Bridge (USA) 486 m - 1883. The largest suspension bridge from 1883 until 1903.
• Williamsburg Bridge (USA) 488 m - 1903. The largest suspension bridge from 1903 until 1924.
• Bear Mountain Bridge (USA) 497 m - 1924. The largest suspension bridge from 1924 to 1926. The first suspension bridge to have a concrete deck. The construction methods pioneered in building it would make possible several much larger projects to follow.
• Benjamin Franklin Bridge (USA) 533 m - 1926. The largest suspension bridge from 1926 until 1929.
• Ambassador Bridge (Michigan-Ontario, USA-Canada) 564 m -1929. The largest suspension bridge from 1929 to 1931.
• Royal Gorge Bridge (USA) 1929 The highest (384 m) suspension bridge in the world.
• San Francisco-Oakland Bay Bridge (California, USA) 704 m -1936 The western portion is two complete two tower bridges end-to-end with a central anchorage, required to avoid dynamic interactions between three main spans between the four towers. Until recently, this was the longest steel high-level bridge in the world. http://www.sfmuseum.org/hist9/mcgloin.html The eastern portion, currently being replaced, will be a self-anchored suspension bridge, the longest of its type in the world.