Without slagging each other off, I would go so far as to say that should I be stuck on a train, and there was no sign of movement, coupled with intense heat and a lack of water, I would most definitely begin evacuation, on a couple of conditions:
Inform the driver, and in real terms, give him the ultimatum that he either rings the Bobby and gets the juice cut / trains stopped for 10 / 20 minutes whilst he evacuates his train, or we walk off and people like me, who are well versed in PTS / 3rd rail do the work and keep everyone safe.
Its not about being arrogant, or self important, or inconsiderate, but you could have people who become ill, or expectant mothers as an example, who really do need to leave the train in those circumstances.
Recently, I was on a train that came to a grinder at Eltham owing to the power suddenly shorting, with an explosion of the clay pots supporting the juice bar. The lights went out immediately, and people became scared. I took my Halo torch out and shone it quickly, don't know how re-assuring that is. We evacuated the train, although it was in the platform, but a couple of us stayed on board, knowing it wouldn't be overly long before we were back on the shift.