If no supporting structure is available in the shape of a building, then either a full- or a half-gantry crane model is used. At times a gantry crane is installed in an existing building, which runs underneath an existing overhead crane, so that an additional and independent material flow can be achieved. One of the two legs is a reciprocating leg, due to the thermal effect of an outdoor positioning, inaccuracies in the crane rail and a sagging of the box girder(s) when under load.
Most full gantry cranes are set up outdoors. This can be either a single-beam or a double-beam crane, without or with corbelling.
Besides the gantry crane itself, a crane rail and a power supply cable are required, the latter with a cable winder.