Exploring the impact of seasonal weather factors on frequency of lane-departure crashes in Maine

Abstract Lane departure crashes account for approximately 34% of all roadway crashes and over 70% of all roadway fatalities in Maine. Despite an 18% decrease in average daily traffic volume, the half of the year with colder weather, from November to April, comprises over 64% of the yearly lane-departure crashes. The purpose of this study is to explore to what extent seasonal (i.e., winter vs. non-winter) and monthly weather variations impact lane departure crashes on rural Maine roads. We used a negative binomial model with panel data to analyze monthly crashes on Interstates, minor arterials, major collectors, and minor collectors from 2015 to 2019 for winter and non-winter periods. The data include monthly average daily traffic, geometric characteristics, and weather variables. The research results indicate that the seasonal variability as reflected in various weather variables significantly impact the frequency of lane-departure crashes during the winter period. The marginal effect analysis shows that as the number of days with more than 1 inch of snowfall, or rainfall increases by 1%, the average number of lane-departure crashes increases approximately by 0.51% and 0.09% on Interstate roadways, respectively.