I'm going to get downvoted for this. But when I ride the train into work that time is used for extra sleep or video games.
I've certainly observed commuters set alarms on their watches/mobiles based on their expected arrival times. I find that a little rude, but nobody else every seems to comment..
The other trick is to keep your naps under 20 minutes. After 20 minutes you fall into a deep sleep, making it harder to wake up and leaving you feeling groggy after you do wake up.