A Bailey bridge is a strong temporary bridge built to a design devised in 1941 for military use by the British civil engineer Donald Coleman Bailey (1901–1985). The steel lattice girders can be assembled by groups of six men from easily manhandled component parts and cantilevered across a gap to provide a bridge to carry 70 tonnes over spans of up to 45 meters (150 feet). The design, a variant of which, resting on plywood floats called "pontoons," is used for crossing broad rivers, has proved of lasting value in peacetime emergencies.