2003 Derailment - Cars Hit Switch Heater's Propane Tank & Burn

[MP57313]

I have seen switch heaters / propane tanks in the colder regions of the US.  But I don't recall hearing about rail cars hitting the tanks and starting a fire (I am used to hearing about tank car contents catching fire). 

The derailment in question occurred on the NS in Bluefield, WV in March 2003, where an auto rack with new cars burned after hitting a switch heater tank.   Is this something (switch heater fires) that happens with any regularity?

M

[CShaveRR]

It could happen wherever there are those pig-shaped propane tanks storing the fuel for the switch heaters.  Train derails at an unfortunate location, car ruptures tank, spark generated by steel against ballast or anything else nearby, and there you go (or at least the lading goes).