When I work on an open train line, there are "derail devices", "torpedoes" and flags placed well down the track. The flags are visual warnings. The "torpedoes" are like giant firecrackers that are set off when the locomotive rolls over them. Any competent locomotive engineer is constantly watching flags and listening for the Pow! Pow! from the torpedoes. If that doesn't get the guys attention, the derail device will certainly keep him from running you down.
It would be very easy to maliciously employ the derail devices.
Would it be easy to get the devices off the track, during the accident and leave with them?
Thinking about all the unknown causes.