Suspension bridges


    In News

    • Recently, the suspension bridge that collapsed in Gujarat’s Morbi killed at least 134 people.
      • The 19th century Bridge, which had been reopened days previously after repairs spanning six months, reportedly had over 400 people on it when it collapsed. 

    About Suspension bridges


    • It is a type in which the deck is hung below suspension cables on vertical suspenders.
    • The basic structural components of a suspension bridge system include stiffening girders, two or more main suspension cables, and towers and anchorages for cables at either end of the bridge.
    • The main cables are suspended between the towers and are connected to the anchorage or the bridge itself. 
      • The vertical suspenders carry the weight of the deck and the commuter load on it.
    • The design ensures that the load on the suspension cables is transferred to the towers at the two ends, which transfer them further by vertical compression to the ground by way of the anchorage cables. 
    • All of this balancing has to happen within the permissible weight restrictions for the bridge, given that the deck is hanging in air, supported by the two sets of cables.
      • Given that the most important load bearing members are the main suspension cables, the entire cross-section of the main cable is the mainstay of carrying the load and ensuring that buckling does not happen. 

    Data/ Facts

    • Suspension bridges are among the most robust structures, starting from the earliest ones made of twisted grass.
    • Bridges worldwide
      • Spanish conquistadors made their way into Peru in 1532; they discovered an Incan empire connected by hundreds of suspension bridges spanning deep mountain gorges.
      • The Golden Gate Bridge and Brooklyn Bridge in the US are examples of suspension bridges.
      • India’s longest single-lane motorable suspension bridge is the 725 metre Dobra-Chanti suspension bridge built over the Tehri Lake.
    • Other type of Bridges 
      • Besides suspension, bridges can be arch bridges, beam bridges, cantilever bridges, truss bridges and tied-arch bridges