Lessons learned from the large-scale application of Driver Feedback Signs in an urban city

Abstract

The City of Edmonton has invested in the installation of Driver Feedback Signs (DFSs) throughout the city starting from 2011. DFSs are dynamic speed display signs aimed at providing positive guidance to drivers with the goal of improving compliance to posted speed limits. Given the city’s extensive history with DFS installation, the goal of this study is to evaluate the safety performance of DFSs and to identify factors that can help in determining the future DFS sites selection. A before-and-after evaluation with Empirical Bayes (EB) adjustment was used to account for regression-to-mean bias and other confounding factors. Local safety performance functions and yearly calibration factors were developed using data from a set of reference urban roads. The EB method analysis was utilized to investigate the effect of DFS on different road and intervention types. Results showed significant collision reductions in all scenarios ranging from 31.0% to 41.6%. DFSs were more effective in reducing collisions for arterials compared to collectors. Also, the combined use of DFS and mobile photo enforcement had a slightly higher effect on safety. Initial collision frequencies, traffic volumes, road lengths and the presence of shoulders were found to impact the reduction in collisions for most collision types.

Keywords:

• Driver Feedback Signs
• Empirical Bayes
• Before-After Evaluation
• Before-After Change Model

Additional information

Funding

The authors would like to thank the City of Edmonton’s Traffic Safety Section for their financial support and for providing the data used in this study.