Well, I thought from the view, when you have modular armor, you don't just die from jumping on or off the train. It is just a quite annoying, that the train stops and your protection is emptied.
But I understand, that this is not the view, that the most have...
So, from that view:
- I stand on the tracks, press Enter and when the train comes I enter the loco. I know this from playing Battlefield... Gives a bit of thrill and is just fun.

- I'm in the train and want to leave: I'll be placed besides the train, far enough away not to collide with the train. Same is already valid for car.
- I "run/roll out" and then stand. I mean: At full speed I need some tiles to reduce my speed to zero (or into the direction I want).
- I can be hurt, when jumping off in this situations:
--- If the speed is too high - I think about 2 times faster then I can run. Well, then it can hurt a lot. But not because I collide with the train, just because I stumble over my feet. The train/car continues.
--- When I collide with something while "running out". A pole or a tree is in the way. I have only minimal control to avoid collision in this "roll out time". I'm not sure, if it should hit also the the object or only the character.
- Optional useful is to choose the side of train (not direction) when leaving.