Chief Types of Bridges

Chief Types of Bridges

The principal types of bridges now in use include: the stone arch bridge, the steel arch bridge, the plate girder bridge, the simple wooden or steel truss bridge, the ribbed arch bridge, the various types of drawbridge, and the suspension and cantilever bridge.

The last two are designed for long spans. A cantilever is a bracket, projecting from a wall to support a balcony. A cantilever bridge is built on this principle, with piers, each of which has two cantilevers. Long girders connect the cantilever with adjacent piers. In many cases, as in the Quebec Bridge, there is a separate central span, which is joined to the cantilever arms.

The suspension bridge is so-called because the deck is suspended from cables that stretch between towers at each end of the span. Longer spans can be built by this method than by any other.