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.

Related Topics:
Bridge - Simple suspension bridge - Pedestrian - Inca rope bridge - Vehicles - Light rail - Cable

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The design of the modern suspended-deck suspension bridge was developed in the early 19th century. Early examples include the Menai and Conwy Suspension Bridges (both opened in 1826) in north Wales and the first Hammersmith Bridge (1827) in west London. Since then, suspension bridges have been built all over the world. This type of bridge is the only practical type usable for very long spans limited by topography or when it would be hazardous to maritime traffic to add temporary or permanent central supports. Many find this kind of bridge to be particularly pleasing to the visual senses. One example frequently cited for its aesthetic appeal is the Golden Gate Bridge at the entrance to San Francisco Bay.

Related Topics:
Menai - Conwy Suspension Bridge - Wales - Hammersmith Bridge - London - Aesthetic - Golden Gate Bridge - San Francisco Bay

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The suspension cables must be securely anchored at each end of the bridge, since any load applied to the bridge is transformed into a tension in these main cables. The main cables continue beyond the pillars to deck–level supports, and further continue to connections with anchors in the ground (An exception is the Royal Albert Bridge (1859) where the anchors are replaced by an arch between the columns.) The roadway is supported by vertical suspender cables or rods. In some circumstances the towers may sit on a bluff or canyon edge where the road may proceed directly to the main span, otherwise the bridge will usually have two smaller spans, running between either pair of pillars and the highway, which may be supported by suspender cables or may use a truss bridge to make this connection. In the latter case there will be very little arc in the outboard main cables. Without special design this type is generally not suited for regional rail applications as the bridge will flex under the concentrated load of a locomotive.

Related Topics:
Royal Albert Bridge - Arch - Regional rail - Locomotive

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