Safety Evaluation of Stop Sign In-Fill Program

Abstract

This paper describes a project undertaken to evaluate the safety impacts associated with the Stop Sign In-Fill (SSIF) program. The SSIF program was launched by the Insurance Corporation of British Columbia (Canada) in 1998 and consists of installing stop signs alternately at every second intersection in residential neighborhoods in the Greater Vancouver Regional District. The main objective of the program is to reduce the frequency and severity of collisions and thereby reduce insurance claims costs in addition to providing a traffic-calming effect on residential neighborhoods. The evaluation included a time series analysis to investigate the effectiveness of the SSIF program on road safety performance at 380 intersections. The evaluation used comparison groups and three techniques to determine the safety impacts of the SSIF program. The first two techniques are based on the odds ratio methodology, while the third is based on the likelihood method. The results of the three techniques were consistent and showed that injury collisions were reduced 61% to 72%, while total collisions were reduced 45% to 55%. It was concluded that the installation of stop signs at uncontrolled intersections in residential neighborhoods was an effective measure for reducing both the frequency and severity of collisions in urban areas.