Great question! I'm one of the developers behind this project and your guesses are good. Other difficult cases include trains stopping between two stations (do

Great question! I'm one of the developers behind this project and your guesses are good. Other difficult cases include trains stopping between two stations (doesn't happen everywhere, but it's frequent in NYC), or a user walking fast onboard a moving train, which can be mistaken for the user having gotten off the train. Taking a train in the opposite directions will break the assumptions we make and we won't know until the next GPS location