Citation

Sayed T, Abdelwahab W, Nepomuceno J. Transp. Res. Rec. 1998; 1635: 140-146.

Copyright

(Copyright © 1998, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

10.3141/1635-19

PMID

unavailable

Abstract

A before and after safety evaluation of the installation of a larger signal head design was conducted. The design consists of a 300-mm red light, a 300-mm amber light, and a 300-mm green light, all with 150-W lamps and a yellow backboard with an additional 50-mm reflective border. The signal head design was field tested in 10 urban intersections in British Columbia. The intersections were originally equipped with the standard signal head design consisting of a 300-mm 150-W red light; a 200-mm 69-W amber light, and a 200-mm 69-W green light, with a yellow backboard. An Empirical Bayes before and after safety analysis indicated that the improved signal head design had a significant effect in reducing the overall frequency and severity of accidents at the treatment sites. Accidents were reduced by approximately 24 percent; injury and fatal accidents were reduced by approximately 16 percent. Classical simple before and after techniques were found to overestimate these benefits by approximately one third. It is concluded that increasing traffic signal visibility through the improvement of signal head design is an effective measure of reducing both the frequency and severity of traffic accidents at signalized intersections.

Language: en