VISSIM 5.30-05 User Manual

6 The Traffic Network
Upon arriving at a reduced speed area, each vehicle is assigned a new
desired speed from within the speed distribution assigned to its vehicle class.
Basically, a reduced speed area is not meant to speed up a vehicle when
reaching it, though this is also possible.
► When approaching a reduced speed area, a faster vehicle reduces its
speed in order to reach its new (slower) speed at the beginning of the
reduced speed area. The deceleration process is initiated according to
the user-defined deceleration value.
► A slower vehicle will not change its speed prior to reaching the start of
the reduced speed area. For vehicles with a slower current desired
speed, the start of a reduced speed area works like a desired speed
decision with that higher desired speed.
A reduced speed area only takes effect for vehicles of the selected vehicle
classes. The vehicle classes of vehicles that should keep their original (slow
or fast) speed when passing the reduced speed area may not be selected for
the list of vehicle classes which are to be regarded by the reduced speed
area.
After leaving the reduced speed area, each vehicle automatically gets its
previous desired speed again. The acceleration at the end of the reduced
speed area is determined by the characteristics of the driver/vehicle unit as
well as the original desired speed. Exception: If two reduced speed areas
with identical properties were defined next to each other in with-flow
direction, the concerned vehicles will keep the new speed even in the section
in-between.
Definition
Prior to the definition of a reduced speed area at least one desired speed
distribution needs to be defined, cf. section 5.2.1.
1. Select the Reduced speed areas mode.
2. Select the link or connector where the reduced speed area should be
placed on.
3. On the link or connector, mark the start of the reduced speed area by
right click on its start position. Drag the mouse along the link/connector
while keeping the right button pressed to define the length of the reduced
speed.
4. Release the mouse button. The Create reduced speed area window
appears.
5. For each selected vehicle class passing that link/connector define the
appropriate speed and acceleration value.
6. Confirm with OK.
Properties & Options
You can define the following properties of a reduced speed area:
202 VISSIM 5.30-05 © PTV AG 2011