Safety assessment of installing traffic signals at high-speed expressway intersections.

This paper reports the status and preliminary results of an ongoing study investigating the safety benefit of signalizing intersections of high-speed (50 mph and greater) divided expressways. Before and after analysis was conducted and compared to empirical Bayesian (EB) techniques. A safety performance function was developed using negative binomial regression for a control group of 67 non-signalized intersections and compared to the performance of 20 intersections signalized between 1994 and 2001. Cross-sectional analysis was performed on 67 signalized and 67 non-signalized locations using negative binomial regression analysis to control for traffic volume. The paper reports on the effect of signalization on crash frequency and compares the results of the EB method with traditional statistical techniques.