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Problem 3

Sub-problem 3a - Page 1 of 5

Sub-problem 3a: Actuated Signal Detection and Signal Timing

Step 1. Setup

In sub-problem 3a, we will evaluate the operational characteristics of the signalized intersection and how the coordinated signal timing parameters affect operations in the field, considering the effect of various volume to capacity ratios on performance. Before we look at the volume to capacity ratios, we will first discuss how actuated signals interact with detectors to determine phase lengths. As mentioned in previous sub-problems, there are three basic types of signal control: actuated, semi-actuated, and pretimed. In this sub-problem we will explore actuated signal control in coordination as it relates to the Reitz Union Drive/Museum Road intersection.

Because Museum Road is a coordinated corridor, a fixed cycle length is required to maintain corridor progression. In Problem 2 we assumed the cycle length for the corridor was 120 seconds and that each approach was phased permitted. In this sub-problem, we will explore how this assumed cycle length is broken into phase lengths. Not only will we look at the average for the hour, but we will also look at how individual cycle lengths vary throughout the hour.

Why would a corridor with progression need to maintain a fixed cycle length? What is the difference between looking at an average hourly cycle versus individual cycles?  How do signal timing parameters affect the phase length? Take a few minutes to consider these questions. Click continue when you are ready to proceed.

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