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.

*Discussion:*

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.