Bridge span replacement system

A method of removing an existing train bridge span, of the type supported on two piers of a train bridge, when installing a replacement train bridge span, the existing train bridge span supporting a length of track overlying the existing bridge span that is in line with a railroad track extending between railroad service areas on either side of the bridge, the method comprising:

• (a) using the railroad track to bring a gantry assembly including a gantry, on a rail vehicle, from one side of the train bridge into horizontal alignment with ground-support locations such that the gantry assembly is positioned over the existing bridge span, the ground support locations supporting a vertical load predetermined to accommodate lifting the existing bridge span with the gantry assembly and located to provide support at positions on both sides of the bridge and on both sides of the railroad track, the positions predetermined to accommodate lifting the existing train bridge span from beneath the gantry assembly and conveying the existing train bridge span away from beneath the gantry assembly;
• and
• (b) causing the gantry assembly to self-lift off the rail vehicle onto the ground support locations.