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Traffic Signal Systems Operations and Design: Isolated Intersections
Prepare two electronic sketches for your subject intersection:
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Sketch #1: Prepare a sketch that shows the lane geometry, the numbered directional movements for
each lane, and the phase numbers that control the movement in each lane. Add to this sketch a stop
bar detector in each lane, numbering
each detector with two digits, the first
number equal to the phase number
controlling that lane. The second
number should correspond to the lane
number beginning with one for the
left most lane for that approach. For
example, if you have two northbound
lanes controlled by phase 2, your
detectors would be numbered 21 for
the left lane and 22 for the right lane as
shown in Figure 106.
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Sketch #2: Prepare a ring barrier
diagram that represents a standard eight
(or five, if T-intersection) phase NEMA
pattern, with protected leading left
turns, for the intersection
Download the VISSIM network that you have been assigned, unzip it, and copy it to your hard drive.
Open the VISSIM network. This network includes the link and node structure, a background photograph,
priority rules governing vehicle interactions, vehicle routing decisions, and traffic volumes. Load the
.ini file from “View,” then “Load Settings.” Run the network (by selecting the “Simulation Continuous”
button) and observe the operation. What is missing?
You will need to add several components to the network, including a signal controller (with a set of given
timing parameters), one detector for each lane, and a signal head for each lane. The process for adding the
signal controller, the detectors, and the signal head is described in the “VISSIM tutorial.”
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Add a Ring Barrier Controller (RBC) with the following signal timing parameters: yellow time = 3
seconds, red clearance time = 1 second, passage time = 5 seconds, minimum green = 15 seconds, and
maximum green = 100 seconds
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Add stop bar detection in each lane with length of 22 feet, and numbered according to the sketch that
you prepared
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Make sure that the detectors are correctly mapped to the phases
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Add signal heads numbered as per the detector numbers that you have prepared
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“Dual entry” should be set for through movements that have been designated as the “start phases”
Figure 106.
Signal head and detector numbering example
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