From the supply side, most public transit systems operate service that has some common travel agency operations manual pdf. The most salient of these are the vehicle cycle and the notion of capacity. Later, we address some operating characteristics of specific modes, notably separating rail modes from fixed-route bus service.
This cycle is illustrated in the figure below. The depot serves as a common location where vehicles are stored or maintained. The vehicle is positioned from the depot to a location where it can begin service.
This is commonly at the terminus of a route. The vehicle travels from its starting location to another route terminus, stopping at stations or stops along the route to allow passengers to board and to alight. While moving along the route, the vehicle incurs both running time and dwell time. Running time is the time spent traveling between stops or stations, and dwell time is the time spent stopped at locations to allow passengers to board and alight.
When it reaches a route terminus, the vehicle is re-positioned for further service. The vehicle continues in revenue service on the fixed routes, repeating the process of stopping at stations or stops to allow passengers to board and alight. When the vehicle has reached its final terminus for its set of trips, it returns to the depot. This vehicle cycle is common to fixed-route service, particularly for bus and rail transit systems.