Safety Effects of Icy-Curve Warning Systems

• DOI: 10.3141/2318-10
• Publication Date: 2013-02-12T02:04:18Z
• Authors: Zhirui Ye; David Veneziano; Ian Turnbull
• Keywords: 13. Climate action; 0502 economics and business; 05 social sciences; 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology

The California Department of Transportation (Caltrans) deployed an icy-curve warning system (ICWS) on a 5-mi section of SR-36 in Lassen County, California, 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 the empirical Bayes technique was used to determine the effects of ICWS on crash frequencies. The results showed that the ICWS reduced annual crashes by 18%. Moreover, analysis of ice-related accidents during winters found that the ICWS had reduced crash severities on this roadway section. On the basis of these results, a benefit analysis revealed that the ICWS provided an estimated monetary benefit of $1.7 million 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.