I remember some science fiction author, probably Asimov, invented a cool version of a train. Basically, next to the train is a series of moving walkways that progressively get slower as they get away from the train. So, the train never stops and people just get on or off wherever they can.

I imagine this style of train would have all sorts of problems, like people guessing wrong about when to start getting off, and ending up in the next town. Or how wherever a popular destination exists, there would be a constant mosh pit of people trying to push their way off.