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.

摘要

从 2011 年开始，埃德蒙顿市已投资在全市安装驾驶员反馈标志 (DFS)。DFS 是动态速度显示标志，旨在为驾驶员提供积极的指导，以提高对张贴速度限制的遵守情况。鉴于该市安装 DFS 的悠久历史，本研究的目标是评估 DFS 的安全性能并确定有助于确定未来 DFS 站点选择的因素。使用经验贝叶斯 (EB) 调整的前后评估来解释回归均值偏差和其他混杂因素。本地安全性能函数和年度校准系数是使用一组参考城市道路的数据开发的。EB 方法分析用于研究 DFS 对不同道路和干预类型的影响。结果显示，所有场景中的碰撞显着减少，范围从 31.0% 到 41.6%。与收集器相比，DFS 在减少动脉碰撞方面更有效。此外，DFS 和移动照片执法的结合使用对安全的影响略高。发现初始碰撞频率、交通量、道路长度和路肩的存在会影响大多数碰撞类型的碰撞减少。