EVER SEE A TRAIN LAY NEW TRACK OVER THE REMOVED EXISTING TRACK?
This is what is happening from Chicago to St. Louis for the high speed rail. The road bed was raised 13 inches to accommodate the new high speed rail line between St. Louis, MO and Chicago, IL.
There are only two of these track laying machines in the world, one here and one in Europe http://www.wimp.com/traintrack/