Demand and supply are both relevant for travel time in public transport. While it is obvious that the supply side in form of the timetable corresponds directly to the travel time, the demand side influences the travel time only partially, but in critical moments. During peak hours, when the demand reaches the capacity of the vehicles, the interaction between demand and supply becomes important. Overcrowded vehicles, hindering passengers to catch their chosen route, lead to longer travel times. Therefore, it is important to integrate the supply side of public transport into a travel demand model.
The supply side of public transport has been integrated into the agent-based travel demand model mobiTopp. A timetable has been implemented, which is used for two purposes. First, it serves as input for the Connection Scan Algorithm, which is used by the agents to find the routes with earliest arrival time at their destinations. Second, it is used for the movement of the public transport vehicles. The model also contains capacity constraints for vehicles, which, when activated, result in a noticeable increase in travel time.
An advanced version of the Connection Scan Algorithm allows creating travel time estimates between zones as matrices and profiles. ... mehrProfiles, compared to matrices, contain for every departure time the corresponding arrival time, while matrices contain mean travel times. Both provide a flexible trade-off between realism and runtime.