Citation

Cronje WB. Transp. Res. Rec. 1986; 1091: 48-59.

Copyright

(Copyright © 1986, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

To optimize a fixed-time traffic signal, a model is required to estimate with sufficient accuracy the measure of effectiveness necessary for the optimization process. Suitable models have been developed for the degree of saturation (x) in the range 0 is less than x is less than 0.9. Reliable models have also been developed for the zone of the degree of saturation x is greater than 1.1. In this zone, traffic can be treated deterministically. However in the range 0.9 is less than or equal to x 1.10, the deterministic approach falls and a model should be based on the probabilistic approach to traffic flow. The ideal model should be applicable over the entire range of the degree of saturation. Only two such models have been encountered in the literature. Because of shortcomings of these models and the lack of a reliable model in the transition zone from undersaturation to oversaturation, an alternative model was developed by Cronje (Transportation Research Record 905, 1983). This model is based on a Markov process and the geomeric probability distribution, and is referred to in this paper as the M Geom Model. In this paper, the M Geom Model is compared with the models developed by Mayne and Catling on a cost basis. Monetary rates are assigned to the measures of effectiveness, namely, total delay and number of stops, for a wide range of cycle lengths, flows, and degree of saturation. The results indicate that the M Geom Model estimates cost more accurately and is consequently recommended for optimizing fixed-time traffic signals.

Language: en

Keywords

HIGHWAY SIGNS, SIGNALS AND MARKINGS; COST ACCOUNTING; PROBABILITY; HIGHWAY TRAFFIC CONTROL - Mathematical Models