VISSIM 5.30-05 User Manual

Signal Controllers
► Start the automatical run for all fixed time SCs, one by one, through the
menu item SIGNAL CONTROL – OPTIMIZE ALL FIXED TIME CONTROLLERS.
Prerequisites and Conditions for Application
The following needs to be defined:
► In VISSIG: signal groups, an intergreen matrix, stages and a stagebased
signal program.
► In VISSIM: signal heads, a surrounding node and adjacent nodes.
Furthermore, the following applies:
► The minimum green times and the relevant intergreens should be
included in the interstages because the optimization can reduce the
stage length to zero. The signal program still needs to be consistent even
if all stages show a length of zero.
► The stage-based signal program has a user-defined cycle time but it can
have arbitrary stage lengths. It is easiest to use the stage lengths that
were the default values upon program creation.
► Select the program number in the Signal Control window in VISSIM.
► Traffic demand and routing must exist in the VISSIM network, too, i.e.
vehicle inputs and routing decisions or parking lots and matrices (or a trip
chain file) and a path file. The routing does not need to be defined as
static turning movements. Dynamic assignment or static routes passing
multiple nodes can also be used, since it only is relevant that the vehicles
traverse the node of the signal controller.
► Other signal controllers are not regarded.
Calculation method in VISSIM
The optimization works in the following way:
► Using an automatically generated node evaluation, VISSIM determines
for each signal group and for the complete simulation run the mean delay
of all vehicles which have passed the node in the particular lanes of the
signal group, i.e. on their particular turning relations.
► For the optimization, the signal group at which the vehicles returned the
greatest mean delay is determined for each stage.
► Subsequently, the stage with the lowest maximum mean delay is
selected for the best stage, whereas the stage with the greatest
maximum mean delay is selected for the worst stage. From the best
stage, one greentime second is removed, to the worst stage, one second
is added. If no second is left over to be removed from the best stage, the
second-best stage will be used. If even this stage cannot be reduced
anymore, iteratively the next worst one will be used. If no stage is left
over for further reduction, the optimization is completed.
► A signal program is always better than another one if the flow (total
number of vehicles passing the node while the simulation is running)
either increased significantly (at least by 25 vehicles or by 10%, if this is
less) or if the flow did not shrink significantly (by 25 vehicles or 10%) and
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