Here’s an entirely non-farm-related post…

As the Washington Metro is expanded into the west, the construction is visible from several of the traffic corridors. This unusual looking device could be seen among the standard array of trucks and equipment.

Evidently some kind of  crane, it’s really an ingenious invention as each railway bridge is assembled much faster. Operating from a horizontal position, the crane hoists several precast concrete bridge segments into position, where they are fastened to the end of the growing bridge span. How the segments are fastened is still not clear (post-tension cabling, superglue?)

Once the crane makes its appearance on the bridgehead, the finished span of bridge will grow longer every day.


Postscript: A Google search yielded a few interesting facts about the crane (dated Dec.2010):

  • Three of these cranes are employed on the Metro extension project.
  • Each crane weighs 365 tons and is 360 feet long.
  • They are operated by an Italian company, Rizzani de Eccher.
  • The bridge segments are approximately 20 feet by 16 feet by 10 feet.
  • The segments are hollow, so construction crews work inside.
  • Approximately 2,700 custom-engineered segments will be constructed nearby, then trucked to the assembly point.
  • The segments are fastened in place using a post-tension process.