ROAD WEATHER INFORMATION SYSTEM CONTRIBUTIONS TO ROAD SAFETY An Assessment of Winter Crash Histories In Alaska

Abstract

Various transportation authorities have relied on road weather information systems (RWIS) to make informed decisions about winter road maintenance. The use of RWIS can provide a variety of advantages in terms of improving road safety. This report provides a solid foundation of information about the development of the use of RWIS across states, as well as a traffic safety analysis of the use of RWIS as a road safety countermeasure to reduce crash rates during the winter season. RWIS have been in use by the Alaska Department of Transportation since 2000; for this investigation 26 of the state’s 75 statewide RWIS stations were considered. The impact of utilizing RWIS on crash rates was captured by using the Empirical Bayes technique. The authors propose that three safety performance metrics be created for winter crashes in Alaska. RWIS as a winter road safety countermeasure is novel, which is why this study established a crash modification factor. The results showed that RWIS implementation has the potential to reduce fatal and serious winter crashes by 36 percent with an expected cost to benefit ratio of approximately 1:27.