The value of headway for a scheduled service

This brief paper derives the value of headway, i.e. the time interval between departures, for a scheduled service. It presents a consistent framework in which users have scheduling costs, time costs and planning costs. The model represents both users who arrive at the station to choose just the next departure and users who plan for a specific departure. Planning for a specific departure is costly but becomes more attractive at longer headways. Simple expressions for the user cost result. In particular, the marginal cost of headway is large at short headways and smaller at long headways. The difference in marginal costs is the value of time multiplied by half the headway.