The timetable-based assignment can include supply of which only the headway is known, but not the exact departure times. Common use cases are:
- High-frequency public transport lines for which no explicit timetable exists even during operation
- Planning lines whose timetable position has not yet been determined
- A subordinate public transport network for which timetable modeling is too complex
Public transport services without information about the departure time can be identified by an input attribute in the timetable-based assignment. Instead of exact timetable data, this supply contains the information about the headway at the time profiles. Differentiation of headway information per time interval is possible. The headway must be greater than zero seconds. Such a supply can be modeled using PuT Aux (Handling of public transport systems of the PuT-Aux type).
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Note: Any number of lines can be modeled headway-based. If only headway-based information is available for the majority of the lines, the headway-based assignment should be used, which better reflects user behavior in these cases (Headway-based assignment). |
The exact departure time of the vehicle journey is unknown; on average, the user experiences a wait time at boarding that corresponds to half the headway. In the procedure, therefore, a wait time is assigned within the path search to each boarding for a headway-based modeled time profile. It is irrelevant whether another path has used this line recently (< headway). The assignment considers the supply exclusively from the user's point of view. The wait time is taken into account according to the set parameters in the perceived journey time and thus in the impedance. Time profiles with a large headway are thus less attractive for the passenger. The division between the connections is analogous to the connection choice (Connection choice).
The wait time before a headway-based path leg is calculated as follows:
- If the headway-based supply is used on the first path leg or follows a headway-based supply, the use is preceded by a wait time that corresponds to half of the defined headway in the time interval.
- If a path leg reaches a transfer to a path leg with a different headway at the end of a time interval, the system checks which departure time is closer: that of the supply in this time interval or that in the next time interval with a different headway plus the duration until the next time interval. The shorter of the two wait times is used.
- If time profiles of different lines are defined as coordinated, their headways are combined and thus the wait time is reduced.
The wait time after a headway-based path leg is calculated as follows:
- No additional wait time is counted at the end of the headway-based path leg.
- If the headway-based supply is the first path leg and followed by a timetable-based path leg, the departure time after the wait time is selected in such a way that direct boarding of the timetable-based path leg is possible.
- If a headway-based path leg lies between two timetable-based path legs, the coupling with the preceding path leg is stronger. The wait time after the headway-based path leg is the difference in time between the arrival of the headway-based path leg attached to the first path leg and the departure of the next timetable-based path leg.
If special transfer wait times are defined between timetable-based and timetable-based time profiles, and the option Use connecting journeys has been selected in the settings for timetable-based assignment, these transfer wait times are decisive (Using Visum: Timetable-based assignment: Headway-based supply page).
