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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 traffic controller operations by inferring the
value of the three standard signal timing parameters by observing traffic flow and signal displays in the
field.
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Infer signal timing parameter values through field observations
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Prepare completed charts with data as required for the following tasks, including inferred values of the
signal timing parameters
You will make field observations for one approach of the same intersection that you studied inActivity
#15 (in Chapter 3) and for which you constructed a ring barrier diagram. You will record the detector
status data and the signal display data for one approach of that intersection using forms shown in Table
10a and Table 10b. A major challenge of this activity is to infer the values of the timing parameters
solely through observation of the vehicle arrival patterns and the signal displays on the approach that
you are observing.
As you are collecting your data, look for traffic conditions that would allow you to observe the
minimum green time, such as a queue of just one vehicle. Also, note that pedestrian calls may affect
your timing observations, so it is best to not collect data when there is a pedestrian call.
1.
One complicating factor in the determination of your timing values is the interaction of your approach
with the opposing approach. Describe how this interaction may affect the conclusions that you make
about the timing values that have been set for your approach for the vehicle extension time.
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Inferring Signal Timing Parameter Values