VISSIM 5.30-05 User Manual

Non-Signalized Intersections
Drivers make a plan how to cross the conflict area. A yielding driver observes
the approaching vehicles in the main stream and decides for which gap he
wants to go. Then he plans an acceleration profile for the next seconds that
will allow him to cross the area, taking into account the situation behind the
conflict area: if he knows that he has to stop or to slow down there because
of other vehicles, he will calculate more time to cross the conflict area or
decide not to go at all.
Vehicles in the main stream react on the conflict area as well: if a crossing
vehicle could not complete the crossing because the driver estimated the
situation too optimistically, the vehicle in the main stream will brake or even
stop. And if a queue builds up from a signal downstream the conflict area,
the vehicles in the main stream try not to stop in the conflict area in order not
to block the crossing stream. This is accomplished by having the drivers
make a similar plan to cross the conflict area as the yielding vehicles do.
A conflict area can be created at any position where two links/connectors
overlap.
Exceptions: In the following cases, this is not possible:
► If the overlapping sections differ in height (z coordinate) by more than 1.0
m
► if the overlapping section is shorter than 0.5 m
► if vehicles cannot use one or both of the overlapping link segments
(since they cannot be reached from a parking lot or by an input)
User Manual © PTV AG 2011 271