Emergency (143/365)

I wonder how many times in one's lifetime will we ever get to use this. and i am also thinking under what circumstances will be we able to use it?

maybe when someone wanna commit suicide? you stop it? then again, when the person jumps, it is usually too late for anyone to stop the train already.

ah! maybe it's for stopping the train when someone accidentally fall in and the train is a distance away. now, that makes more sense. and how often do we get to see it?