All assignments in Visum in PrT as well as in PuT are path-based, meaning that possible paths are calculated for each OD pair and loaded with a demand share. All other results, especially the different network object volumes and the skim matrices are derived from these loaded paths. These paths are saved with the assignment result and can be analyzed after the assignment for flow bundle calculation, for example.
A path first describes the exact local course of a change of location in the network model, which means that all traversed network objects such as nodes, links, turns, main nodes, connections, and if applicable also stops, line routes, and time profiles are known. If the departure time and thus the temporal course is added to the spatial course, we are taking about a connection, otherwise a route. For PuT paths, in addition to departure time for a connection compared to the route, the information on used vehicle journeys is included.
If an assignment produces routes or connections depends on the type of assignment. Dynamic PrT assignments and the timetable-based PuT assignment create connections, static PrT assignments as well as the headway-based PuT assignment calculate routes. In principle, the user can select, whether internally calculated connections should be saved as such or only as routes, or not at all – respectively for PrT (Using Visum: Settings for saving PrT assignment results) and PuT (Using Visum: Settings for saving PuT assignment results). If you do not save the connections, less memory is required, however, posterior analyses of the connections are no longer possible, even if a dynamic assignment procedure was applied. Network volumes are still calculated and can even be output differentiated according to analysis time intervals.
