VISSIM 5.30-05 User Manual

6 The Traffic Network
6.6 Non-Signalized Intersections
In VISSIM, non-signalized intersections as well as separating or joining links
can be modeled by appropriate modeling techniques. In this section, these
methods are described in detail.
6.6.1 Priority Rules
The right-of-way for non-signal-protected conflicting movements is modeled
with priority rules. This applies to all situations where vehicles on different
links/connectors should recognize each other. Vehicles within the same link
will implicitly see each other, even if the link has multiple lanes.
6.6.1.1 Principles
Actually, conflict areas are recommended for modeling. If these do not
return the expected results, the experienced user can model priority rules.
If the Pedestrians add-on is included in your installation, then priority rules
can also be defined for conflicting flows of pedestrians as well as for the
interactions of pedestrians and vehicle flows, cf. section 7.1.5.
A priority rule consists of
► one stop line and
► one or more conflict markers that are
associated with the stop line.
Depending on the current conditions at the
conflict marker(s) the stop line allows
vehicles to cross or not.
The two main conditions to check at the
conflict marker(s) are
► minimum headway (distance) and
► minimum gap time.
As a rule of thumb, for free flow traffic on the
main road the min. gap time is the relevant
condition. For slow moving or queuing traffic
on the main road the min. headway
becomes the most relevant condition.
conflict marker
connector headway
stop line
conflict area
The minimum headway is typically defined as the length of the conflict area.
During the simulation the current headway is determined by the distance
between the conflict marker (green bar) and the first vehicle approaching it. If
any part of a vehicle is located on the green bar the resulting headway is 0m.
Whenever the current headway is less than the minimum headway, the cor-
258 VISSIM 5.30-05 © PTV AG 2011
headway
relevant gap for min. gap time