Launching gantry

A launching gantry (also called bridge building crane, and bridge-building machine) is a special-purpose mobile gantry crane used in bridge construction, specifically segmental bridges that use precast box girder bridge segments or precast girders in highway and high-speed rail bridge construction projects. The launching gantry is used to lift and support bridge segments or girders as they are placed while being supported by the bridge piers instead of the ground.

While superficially similar, launching gantry machines should not be confused with movable scaffolding systems, which also are used in segmental bridge construction. Both feature long girders spanning multiple bridge spans which move with the work, but launching gantry machines are used to lift and support precast bridge segments and bridge girders, while movable scaffolding systems are used for cast-in-place construction of bridge segments.