PTV Visum - Frequently Asked Questions (FAQs)
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How can I close links for through traffic but keep them open for residential traffic?
- Differentiate per TSys set and Demand segment: This method is suitable to model e.g. HGV bans. The banned links are closed for a TSys HGV, but open for a TSys HGV_local. This method needs a split up of the demand matrix.
- Differentiate per TSys impedance input attribute on links or turns: Raise some user-defined impedance attribute values only for cordon links and turns, to add to the impedance of through traffic, influencing the route choice only for the through traffic. The residential traffic impedance is raised too, but without route choice changes. (Calculate -> General procedure settings -> PrT settings -> Impedance -> (Select a TSys) -> Use the option 'In detail' -> (Create functions for links or turns holding some user-defined impedance attribute))
(Note: 'Impedance-PrTSys (P,AP)' is an output attribute)
- Differentiate per Link type: Use the option 'Closed' of the Volume-delay function, dedicated per Link type. (Calculate -> General procedure settings -> PrT settings -> Volume-delay functions -> Link types -> (Select a Link type) -> Volume-delay functions -> Edit)
- Differentiate per Turn type: Use the option 'Closed' of the Volume-delay function, dedicated per Turn type. (Calculate -> General procedure settings -> PrT settings -> Node impedances -> Turns VDF -> (Select a Turn type) -> Volume-delay functions -> Edit)
If this option has been checked, the particular network object will only be included in path search if no alternative path can be found (e.g. for residential traffic). In this case, Visum assigns a high virtual time penalty, which, for example, has to be considered in the travel time skim matrix, when evaluating path times.
If this option has been checked, the particular network object will be excluded from path search.
The option 'Hard closure' is only visible, if option Closed has been checked.
(Ref.: Manual 'Applying userdefined volumedelay functions')