Most short bridges are supported only by the abutments and are called single-span bridges. Longer bridges usually have one or more piers to support them and are known as multi-span bridges. Girder bridges are made of beams called girders. The ends of the beams or girders rest on piers or abutments. Truss bridges are supported by frameworks called trusses.
Trusses are beams arranged to form triangles .
Arch bridges are structure sin which each span forms an arch. The arch bridge is one of the oldest types of bridges. The spans range up to abut 1700 ft. Cantilever bridges consist of two independent beams, cantilevers, that extend from opposite banks of a waterway. Cantilever bridges have spans as long at 1800 ft.