Study Details

Study Title: Safety Effects of Icy Curve Warning Systems

Authors: Zhirui et al.

Publication Date:JAN, 2012

Abstract: The California Department of Transportation (Caltrans) deployed an Icy Curve Warning System (ICWS) on a five-mile section of State Route (SR) 36 in Lassen County over Fredonyer Pass. This section of roadway had a history as a high-crash location, with multiple fatal crashes. The vast majority of these accidents occurred when the pavement was icy, despite static signage that Caltrans had installed to increase motorist awareness. This study presents the results of research that investigated safety effects of the ICWS. An observational before-after study method with Empirical Bayes technique was used to determine the effect the ICWS on crash frequencies. The results showed that the ICWS reduced annual crashes by 18%. Moreover, analysis of ice-related accidents during winter seasons found that the ICWS had reduced crash severities on this roadway section. Based on these results, a benefit analysis revealed that the ICWS provided an estimated monetary benefit of $1.7 million dollars per winter season to motorists through reduced crashes. The study results are anticipated to contribute to a better understanding of safety effects of ice (or icy curve) warning systems and increase the knowledge base of weather-specific treatments and their associated effects.

Study Citation: Zhirui, Y., Veneziano, D., Turnbull, I., "Safety Effects of Icy Curve Warning Systems." Presented at the 91st Annual Meeting of the Transportation Research Board, Paper No. 12-0985, Washington, D.C., (2012)

CMFs Associated With This Study

Category: Advanced technology and ITS

Countermeasure: Install icy curve warning system

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.82183 StarsAllAllNot SpecifiedRural