New Optimal Cycle Length Formulation for Pretimed Signals at Isolated Intersections
Publication: Journal of Transportation Engineering
Volume 130, Issue 5
Abstract
Under near-saturated or saturated conditions, the optimal cycle length formulation proposed by Webster becomes infeasible because (1) it generates an unreasonably large cycle length as the intersection critical flow ratio approaches one, and (2) it becomes inapplicable if the intersection critical flow ratio is equal to or greater than one. An attempt is made here to rectify this deficiency by providing a simplistic but reasonably accurate formulation for optimal cycle length under saturated conditions. Using the optimal timing variables obtained based on the delay minimization criterion, the functional relationship between optimal cycle lengths and traffic flow parameters, including intersection critical flow ratio, total lost time, and duration of analysis period, is established through a nonlinear regression analysis. The resulting formulation generates fairly accurate estimates of optimal cycle length with 5.7% average deviation from the analytical solutions. The corresponding average delay, however, only deteriorates about 0.9%. The timing plans consisting of the proposed optimal cycle estimates and the equalized degree-of-saturation green splits produce near-optimal delay performance with 3.3% degradation from the optimal solutions.
Get full access to this article
View all available purchase options and get full access to this article.
References
Casella, G., and Berger, R. L. (1990). Statistical inference, Duxbury Press, Belmont, Calif.
Federal Highway Administration (FHWA). (2002). TSIS user manual, Ver. 5.1.
Roess, R. P., McShane, W. R., and Prassas, E. S. (2001). Traffic engineering, 3rd Ed., Prentice-Hall, Englewood Cliffs, N.J.
Transportation Research Board (TRB). (2000). Highway capacity manual, National Research Council, Washington, D.C.
Webster, F. V., and Cobbe, B. M. (1958). “Traffic signals.” Road Research Technical Paper No. 39, Her Majesty’s Stationery Office, London.
Information & Authors
Information
Published In
Copyright
Copyright © 2004 American Society of Civil Engineers.
History
Received: Jan 24, 2003
Accepted: Sep 10, 2003
Published online: Aug 16, 2004
Published in print: Sep 2004
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.