How to construct a multiple span bridge:
Launching Gantry: Massive 580 Ton Chinese Girder Erection Machine
A bridge needs to be built, so time to bust out the cranes, right? Not so fast, a Chinese company has built a machine that has a creative way of setting girders into place.
The SLJ900/32, made by the Beijing Wowjoint Machinery Company, is a 580 ton, 300 foot long and 24 foot wide mega machine that looks more like a train than a crane and acts a lot like a Stretch Armstrong action figure. Instead of using a stationary or crawler crane to lift the girder of a bridge from the ground and drop it into its place, the SLJ900/32 drives the girder onto the previously placed girder, slowly extends its arms to the next support platform, pushes the girder towards the front of the machine and then lowers it into place.
download a brochure on this gantry (19.8 mb zipped file)
original source: constructionjunkie.com