Pasi : I’m quite sure that this is not how it work. The game can not predict if train will be full or not, if they will be stuck because of other trains, if trams/buses will be stuck because of other cars etc… So there could be passengers with a potential travel time of less than 20min which disapear because the travel actually take more than 20 min. And i think this is the main reason of passenger disappearing. It’s quite common on busy lines.