I suggest the implementation of strategic beacons that the FBD units aim for. The initial placement of these beacons could be scripted and the routine that decides to change placement should take change over time in account (i.e. the time it would take to rail an FBD to the new starting point). This beacon functionality could possibly be made available to human players as well.
As a stop gap, I suggest an At Start option (check box) that would repair all eligible rail hexes within 4 hexes of current railhead (6 for Baltic), as if each rail line had its own FBD, this for the first 5 or so turns (number of turns possibly configurable).
This way we might get better challenge when playing against the Ai as soviet.
