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Chapter 4: Actuated Traffic Controller Timing Processes
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The purpose of this activity is to test your understanding of the basic timing processes for an actuated
traffic controller.
•
Complete a traffic control process diagram describing the response of the detectors, the timing
processes, and the displays to a pattern of vehicle demand
•
Prepare a document with copies of the completed charts as required from Tasks 1 and 2
The traffic control process diagram (Figure 80, following page) shows the vehicle trajectories in a time
space diagram format as well as the timing parameter values (bottom right of figure). Draw the detector
status, the timer status, and the display status. Show the graphs for the values of the three timing processes
in the spaces provided, noting the maximum and minimum values of the processes on the y-axis. The
resulting signal display may change some of the vehicle trajectory plots. Note on the figures where you
think that these changes will occur. Assume a yellow time of 3 seconds. Assume that the green time starts
at
t
= 0. Also assume that the conflicting call begins at
t
= 0 and continues throughout the green duration.
Figure 81 and Figure 82 (see following pages) show traffic control process diagrams without the vehicle
trajectories, but with the detector status data for both the active and the conflicting phases. The values of
the timing parameters are given in the lower right of the two figures. Show the resulting timing processes
in the form of a chart showing the value of the timing parameter as long as the green is active for that
phase. Show the resulting signal display status, noting only when the display changes. State how the phase
terminates in each case. Assume a yellow time of 3 seconds. Assume that the green time starts at
t
= 0.
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What Do You Know About Controller Operations?