A launching gantry (also called beam launcher, girder launcher, bridge building crane, and bridge-building machine, locally nicknamed the "Iron Monster") 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.