Citation

Lin FB, Mazdeyasna F. Transp. Res. Rec. 1983; 905: 33-38.

Copyright

(Copyright © 1983, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Traffic-actuated signal controls have more control variables for engineers to deal with than a pretimed control. The increased sophistication in their control logic provides greater flexibilities in signal control but also makes the evaluation of their performance more difficult. At the heart of the problem is that traffic delays cannot be readily related to the control variables of a traffic-actuated control. This prompts practicing engineers to rely mostly on short-term, subjective field observations for evaluation purposes. To provide an improved capability for evaluating alternative timing settings, delay models are developed in this study for semiactuated and full-actuated controls that employ motion detectors and sequential phasing. These models are based on a modified version of Webster's formula. The modifications include the use of average cycle length, average green-duration, and two coefficients of sensitivity that reflect the degree of sensitivity of delay to a given combination of traffic and control conditions. Average cycle length and average green duration are dependent on the settings of the control variables and the flow pattern at an intersection. They can be estimated by existing methods.

Language: en

Keywords

ROADS AND STREETS - Intersections; TRAFFIC SURVEYS; TRAFFIC SIGNS, SIGNALS AND MARKINGS - Control