PTV Vissim - Frequently Asked Questions (FAQs)

(#VIS19302)

Some conflict areas appear to operate with different priority than that as coded. Yielding vehicles appear to take priority. Why is this and how can I avoid this?

In order for a vehicle to react in a conflict area it has to see the end of the conflict area.

Workarounds:
- Raise the attribute value 'Observed vehicles in front': Base Data > Driving Behaviors.
For long conflict areas it may happen that the defined number of 'Observed vehicles in front' is too low to accomodate for all vehicles (the conflict area is internally counted as vehicle as well).
- Raise the attribute value 'Look ahead distance (minimum)': Base Data > Driving Behaviors.
This ensures that vehicles see the end of the conflict area, independently of the number of 'Observed vehicles in front'. We recommend to apply this driving behavior only to those links/connectors where it is required in order to keep the simulation speed as fast as possible.
- Use the network object 'Priority Rules'.
Conflict areas seem sometimes being ignored by vehicles, e.g. because other vehicles keep waiting because of another Conflict area. With a Priority Rule you can model to keep an intersection clear.
(Re.f: Manual 6.13.2.3 It is better to use conflict areas than priority rules to model driving behavior.)