Bridge Erection Machine

Single-girder bridge erection machine

This bridge construction machine has a box-section boom projecting forward, with a folding front support formed by left and right legs. It can travel into the bridge position unloaded, extend its front support and rest it on the next pier. As the girder segment or complete girder moves along the boom, the boom approaches the condition of a simply supported beam.

During erection, the machine moves into position unloaded. A special gantry crane first transfers the girder from a railway flatcar to a dedicated girder carrier. The carrier aligns with the rear of the erection machine. Two lifting trolleys travelling on the boom lift the girder, carry it forward and lower it into position. The boom can swing slightly in the horizontal plane for curved bridge erection.

Placement follows the same method as a double-cantilever erection machine, by shifting the girder or slewing the track. Advantages include eliminating counterweights and locomotive pushing, removing the need for a bridgehead siding to feed girders, increasing mechanization and improving safety. The 130-tonne Shengli erection machine is an example of this type.