In the segmental method of bridge construction, 4 units (or segments) of the bridge are precast, assembled in appropriate position and tied together by prestressing to form the bridge superstructure. Segments can also be cast in place. Several methods are used for erecting segmental bridges. One common method suitable for medium to long span bridges is called the "Cantilever Construction." In his method, segments are placed progressively to form a balanced cantilever, starting generally from the piers. When the cantilevers from two adjacent piers meet, they are joined together to form a continuous span. Continuity prestressing cables are often used to resist bending moments caused by superimposed loads and those developed gradually with time as a result of creep and shrinkage of concrete and relaxation of prestressed steel.
