A
cantilever bridge is a
bridge built using
cantilevers, structures that project horizontally into space, supported on only one end. For small
footbridges, the cantilevers may be simple
beams; however, large cantilever bridges designed to handle road or rail traffic use
trusses built from
structural steel, or
box girders built from
prestressed concrete. The steel truss cantilever bridge was a major engineering breakthrough when first put into practice, as it can span distances of over , and can be more easily constructed at difficult crossings by virtue of using little or no
falsework.