An increasingly popular alternative to Overhead Bridge Cranes are Gantry Cranes, operating on a runway at floor level. Available in DG & SG, Portable or Fixed. The bridge is supported by a pair of rigid steel legs, carried by a pair of end trucks along the floor level runway.
This structure is considered an Overhead Crane, used to straddle an object or workplace/workload in a fixed location. The support comes from a rectangular frame upon which the crane can move forwards and backwards as well as left to right or fixed with columns or portable wheels.