VISSIM 5.30-05 User Manual

Behavior at red/amber signal
Driving Behavior
This parameter defines the vehicle behavior in front of a signal control
showing red/amber.
For the driving behavior parameter set, you can select Go (same as green)
or Stop (same as red) to adjust the behavior to different country/region
specific habits or rules:
Reduced safety distance close to a stop line
These parameters define the vehicle behavior close to a stop line.
● Reduction factor: Within the given distance from Start to End, the userdefined
reduction factor is applied to the vehicle´s desired safety
distance, cf. section 5.4.3.
For lane changes in front of a signal control, both the resulting values are
compared to each other. VISSIM will use the shorter distance.
● Start upstream of stop line: Distance upstream of the signal head.
● End downstream of stop line: Distance downstream of the signal head.
5.4.6 Changing the Saturation Flow Rate
In VISSIM the saturation flow is a result of a combination of parameters that
are relevant for the simulation. Thus the saturation flow cannot be explicitly
defined but experienced users may want to change the relevant driving
behavior parameters in order to get a different saturation flow rate. The
saturation flow rate defines the number of vehicles that can free flow on a
VISSIM link during a period of one hour.
Depending on the selected Car following model different Model parameters
are available, cf. section 5.4.2.1 and section 5.4.2.2 for details.
Wiedemann 74 Car Following Model
The model contains two parameters which have major influence on the
safety distance and thus affect the saturation flow rate.
These parameters are:
► Additive part of desired safety distance (bx_add) and
► Multiplicative part of desired safety distance (bx_mult)
Apart from that the saturation flow rate is also dependent on many other
parameters, such as vehicle speed, truck percentage, number of lanes etc.
The results shown in the graph below provide the resulting saturation flows
for some specific VISSIM examples only. The results will be different for
networks that do not conform with the properties of these examples.
The graph below is based on the following assumptions:
► single lane link,
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