Boston eliminated the last of its subway exit fares years ago. (The system is famous for the song Charlie on the MTA, about a man trapped on the train due to an

Boston eliminated the last of its subway exit fares years ago. (The system is famous for the song Charlie on the MTA, about a man trapped on the train due to an increase in the exit fare.) There are a couple of bus routes that require payment on exit. However, it's not a variable fare. It just works that way because the configuration at Harvard station requires entry on the left side side (without the farebox) and exiting curbside. So people pay as they leave, instead of when they board.