I wonder if clean up was part of the costs. I imagine there's quite a few parts that are difficult to move without heavy machinery. Or did they just leave the wreck and tracks as is? If so are there any of those crash sites still visible?
Doing that just takes a lot of people and labor (you've probably seen old films of track laying from the late 1800s-early 1900s).
They wouldn't install a switch, as that would be too costly for something so temporary; so they probably just broke the track, moved it sideways a bit, connected it to the new "spur", moved the trains/cars onto it, then reconnected it back to the original line to allow traffic thru. Then basically the reverse to move in equipment to dismantle/haul away the remains.
Train robbers are land pirates.