This New York Times article describes a relatively new "accelerated bridge construction" technique using a self-propelled modular transport to lift a bridge into place.  The article focuses on the River Street Bridge in Boston, but the technique is being used increasingly around the country.  When done correctly, the bridge is lowered in place "like a lid fitting onto a box."  The primary benefit of this technique is the incredible increase in speed of project completion, shaving months or even yeras off of a project.   Click here to read the article.