Estimating Safety Impacts of Adaptive Signal Control Technology Using a Full Bayesian Approach

Abstract

Adaptive signal control technology (ASCT) is a traffic management strategy that optimizes signal timing based on real-time traffic demand. Although the primary intent of ASCT is to improve the operational performance of signalized intersections, the technology may also have substantial safety benefits. This study explored the potential safety benefits of the ASCT strategy deployed at signalized intersections in Florida, U.S. An observational before-after full Bayes (FB) approach with a comparison group was adopted to develop crash modification factors (CMFs) for total crashes, rear-end crashes, and specific crash severity levels (fatal plus injury [FI], and property damage only [PDO] crashes). The analysis was based on 20 intersections equipped with ASCT and their corresponding 40 comparison intersections without ASCT. The ASCT deployment was found to significantly reduce total crashes by 7.8% (CMF = 0.922), rear-end crashes by 8.7% (CMF = 0.913), and PDO crashes by 8.1% (CMF = 0.919). The 8.6% reduction in FI crashes (CMF = 0.914) was not significant at a 90% Bayesian credible interval. These findings provide researchers and practitioners with an effective means to quantify the safety benefits of the ASCT strategy and conduct economic appraisals of ASCT deployments.

Modeling Highway-Rail Grade Crossing (HRGC) Crash Frequency

“…Bayesian statistics was applied, which is an assumption method that uses probability distributions to de ne the state of knowledge about unknown quantities (Kodi et al 2021). Bayes' theorem is a mathematical result relating conditional probabilities to perform the updating of probability distributions (Stern 2015).…”

Impacts of COVID-19 on the Operational Performance of Express Lanes and General-Purpose Lanes

“…Since there is no study which has a similar set of analysis as the current study, the authors selected non-informative priors in the estimation of parameters. This approach has also been used in previous studies ( 12 – 18 ). The non-informative priors have a negligible influence on the estimates ( 11 ).…”