If the brakes are out, how is the train going to stop when it reaches the terminus? The people on the train are alll doomed anyway!

Anyway, what if I carry a knife to cut the ropes with? (Not to mention dialling 999 on my n900 as I do so)

It's easy: I'd scoff so much chocolate that I'd become as fat as the fat man, and then interpose my podgy self between the train and the people on the tracks. That way, the only life lost is mine, and cadbury's shares rise through the roof.