I wonder how bunker busters would affect the repair time of railroads by massive cratering and soil destabilization?
I don't think it would significantly affect repair times. Yes a 2,000lb bomb leaves a larger crater but a 500lb bomb crater still needs to be filled and compacted before laying ballast and track.
The crater left by a 2,000lb bomb will just need more fill and compacting before fresh ballast and track can be laid.