Back Continue

Getting Started
Problem 1
Problem 2
Problem 3
Problem 4
Problem 5
Problem 6
Problem Index

Problem 4 - Page 2 of 2

ID# C104002

Problem 4: Actuated Control

The traffic-actuated timing procedure requires three control parameters:


Minimum phase times, considering driver expectancy and pedestrian requirements. The minimum times from the pretimed example (sub-problem 1b) will be used here.


Maximum phase times to assure a reasonable distribution of green time on cycles with heavy demand. The literature contains a variety of techniques for setting maximum green times. For purposes of this example, the maximum green times will be set to their corresponding pretimed values.

bulletUnit extension times to determine the length of the gap in arriving traffic at which a phase will terminate. Most traffic models, including the HCM, will yield lower delay estimates with lower unit extension times. As a practical constraint, however, the unit extension must be slightly longer than the maximum expected gap between vehicles departing from a queue, or premature phase terminations will occur. For the purposes of this example, the unit extension times will be set to 3 seconds for single lane operation and 2 seconds for multiple-lane operation.

This problem illustrates some of the important elements of performing an analysis of a signalized intersection operating under actuated control by addressing the following issues as they relate to the proposed signal at the U.S. 95/Styner-Lauder Avenue intersection:

Sub-problem 4a: Estimating phase times for actuated signal control

Sub-problem 4b: Effects of Unit Extension on intersection operating characteristics

Sub-problem 4c: Coordinating a system of actuated controllers

Sub-problem 4d: Coordinated operation of an actuated controller with left-turn protection

[ Back ] [ Continue ] to Sub-Problem 4a