Skims for path sequences cannot be calculated the same way as conventional skims for PrT or PuT. This is because different assignments are used, whose skims do not automatically result in a uniform skim for path sequences. Furthermore, additional components might play a role when the mode is changed in a zone. This is why you need to define skims for path sequences, specifying what they shall include (Using Visum: Calculating skim matrices from path sequences). Typically, skims of time, distance or monetary cost are also of interest for skims of path sequences. If, for instance, for a path sequence the modes PrT, PuT-Intercity and PuT-Local are used, a skim of time is calculated for the path sequence, e.g. based on the journey time in a loaded network (tCur) of the PrT demand segment, plus the run time of the respective PuT demand segments for the following paths.
Skims for path sequences can be calculated with the procedure Calculate skim matrix from path sequences. The value of a skim is calculated as the weighted average of the volume on all path sequences of the respective relation and path sequence set.
Prerequisites for calculation:
- Path sequences with volumes and an assignment of used demand segments for the paths must be available.
- Skims for path sequences have been defined in the General procedure settings. A matrix formula has been defined for the subordinate demand segments used. This matrix formula may contain one or multiple skims of the demand segment as well as zone attributes of the origin or destination zone.
- The skims used in the matrix formulas must be calculated for all subordinate demand segments used.
Unlike PrT and PuT skims, the skims for path sequences are user-defined. Matrix attributes are added to the skim matrices according to the path sequence set, i.e. if available, together with the demand segment code or demand stratum code and the code of the skim matrix for the path sequence. Skims for individual paths sequences are displayed even if there are no corresponding matrices available.
