Assessing the Effectiveness of Centerline Rumble Strips Accounting for Winter Maintenance Operational Levels on Wyoming Highways Using Before–After Empirical Bayes

Abstract

Lane departure crashes account for more than 50% of traffic fatalities in the US. Among the different roadway treatments, rumble strips was found to be cost-effective. Centerline rumbles strips (CLRS), provided on the centerline for two-lane two-way highways, alert distracted and drowsy drivers from drifting into the opposite driving lane. It is used as a countermeasure for head-on or cross-over crashes. Despite public concerns of the generated noise and perceived decrease in visibility of pavement markings, there is no doubt about the safety benefits of CLRS. During severe snowstorms, compacted snow located on the roadway could negatively influence the performance of CLRS. Higher and more frequent winter maintenance level operation might accelerate the functional restoration of CLRS. The gap in literature was approached by quantifying the effect of CLRS in reducing crashes accounting for different levels of winter maintenance operations. Wyoming highways with distinct winter maintenance levels were assessed in this study, in which safety performance functions (SPFs) were developed. Unobserved heterogeneity in between-route variance was accounted for by utilizing random-intercept negative binomial (NB) model in a Bayesian framework. Crash modification factors (CMFs) were developed using the before–after empirical Bayes (EB) method. Generally, the safety benefits of installing CLRS on the selected routes was between 25% and 68% expected crash reductions at 95% significance level. Higher level of winter maintenance was also found to be associated with higher effectiveness of CLRS. Therefore, the agencies should re-evaluate their winter maintenance plans in order to account for locations with high-risk for head-on collisions.