title: Contributing factors to vehicle to vehicle crash frequency and severity under rainfall.
abstract: BACKGROUND
  This study combined vehicle to vehicle crash frequency and severity estimations to examine factor impacts on Wisconsin highway safety in rainy weather.
  
  
  METHODS
  Because of data deficiency, the real-time water film depth, the car-following distance, and the vertical curve grade were estimated with available data sources and a GIS analysis to capture rainy weather conditions at the crash location and time. Using a negative binomial regression for crash frequency estimation, the average annual daily traffic per lane, the interaction between the posted speed limit change and the existence of an off-ramp, and the interaction between the travel lane number change and the pavement surface material change were found to increase the likelihood of vehicle to vehicle crashes under rainfall.
  
  
  RESULTS
  However, more average daily rainfall per month and a wider left shoulder were identified as factors that decrease the likelihood of vehicle to vehicle crashes. In the crash severity estimation using the multinomial logit model that outperformed the ordered logit model, the travel lane number, the interaction between the travel lane number and the slow grade, the deep water film, and the rear-end collision type were more likely to increase the likelihood of injury crashes under rainfall compared with crashes involving only property damage.
  
  
  CONCLUSIONS
  As an exploratory data analysis, this study provides insight into potential strategies for rainy weather highway safety improvement, specifically, the following weather-sensitive strategies: road design and ITS implementation for drivers' safety awareness under rainfall.
authors.affiliation: Hanyang University Erica Campus, Department of Transportation and Logistics Engineering, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan 426-791, Republic of Korea. Electronic address: jung2@hanyang.ac.kr.
authors.forename: Soyoung
authors.initials: S
authors.lastname: Jung
authors.affiliation: Korea Advanced Institute of Science and Technology, The Cho Chun Shik Graduate School for Green Transportation, 2116-1 Eureka Bldg., 335 Gwahak-ro, Yuseong-gu, Deajeon 305-701, Republic of Korea. Electronic address: kitae.jang@kaist.ac.kr.
authors.forename: Kitae
authors.initials: K
authors.lastname: Jang
authors.affiliation: Korea Advanced Institute of Science and Technology, Department of Civil and Environmental Engineering, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. Electronic address: yoonjin@kaist.ac.kr.
authors.forename: Yoonjin
authors.initials: Y
authors.lastname: Yoon
authors.affiliation: Construction and Economy Research Institute of Korea, 11th F. Construction Bldg, 711 Eonjuro, Kangnam-gu, Seoul 135-701, Republic of Korea. Electronic address: shkang@cerik.re.kr.
authors.forename: Sanghyeok
authors.initials: S
authors.lastname: Kang
mesh_terms: D000063:Accidents, Traffic / Q000145:classification / Q000706:statistics & numerical data*; D017677:Age Distribution; D003198:Computer Simulation; D016208:Databases, Factual; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011336:Probability; D011891:Rain; D012044:Regression Analysis; D018570:Risk Assessment; D063507:Sexism; D014922:Wisconsin / Q000453:epidemiology
keywords: Crash frequency and severity; Exploratory data analysis; Rainy weather; Vehicle to vehicle; Weather-sensitive strategies