Each location is different. I am 300 metres from a feeder train track (slow-moving trains) and 2 km from a refinery. While a derailment probability is quite low, it is still possible. A lot of commodities like steel, cars, lumber, wheat and potash run right past me. None of those are harmful. An oil spill would be an environmental nightmare but not necessarily a dangerous one. Mind you, even in a high speed derailment, container cars are designed not to leak. However, anhydrous ammonia cars are another story. (There is an ammonia gas plant 50 km away). In theory if there was a derailment and the ammonia was released it could be a matter of minutes before it could affect me with the right wind. Bugging out in that situation would have to be immediate and I may not even have the time to get my vehicle out of the garage and drive away. Actually by the time I would be aware of the ammonia it would be too late or it might be safer to stay in the house (shelter-in-place) and not try to go outside.