Personal Width

Actually I think this is wrong. Your seat should be = max(width of bottom, width of shoulders). A related issue is that, in trains people often fall asleep on the shoulder of their neighbour. In a way this is cute as it seems so trusting, but after a while it gets annoying. If the sleeper is elbowed hard enough they will sometimes start leaning the other way, and then it become a competition between the people on either side as to who is prepared to be the most violent. Only rarely does this cause the sleeper to actually wake up.