We haven't had a derailment here since 2009 where a train left the track by about a foot or so. It could happen, but in the course of normal business operations, evacuations are not a regular event here pulling operators out of their cabins. More likely is a door breaks (or rather someone breaks a door) and they have to seal it manually to keep the train moving, but I only see that happen on the older >20 years old stock and pretty much never on the newer stock.

The incident I was thinking of was about 2007 at Mile End.

Sure it’s rare. But what happens when it does happen, last thing you want is passengers self evaccing onto 3rd/4th rail energised tracks.