By implication, it's a self-contained system, not a rail car, and not anywhere near that size. Since we don't have rail-mobile combat vehicles as anything but cargo, it's an advanced support vehicle. If you want a simple answer, treat it as an LT-MOB-25 system that goes 3/5 or 4/6 but follows the rail vehicle rules in TacOps.
If you want a complicated answer, someone's going to have to do some math and the appropriate place for it is Fan Designs, not in here.