Influence of winter road maintenance on traffic accident rates

Highway maintenance involves all work necessary to assure that the highway system is kept safe, open to traffic, and in proper working order. During winter, the removal of snow and ice from streets, roads, and highways is a major maintenance operation. Snow and ice covered roads can paralyze the functioning of the community and pose a considerable threat to the public safety. Prior to 1991, several extensive European studies have been reported on measuring the impact of winter road maintenance and its economic benefits on road users' safety. In the United States, no such study up to the date of this dissertation has been conducted in documenting quantitative data of how effective is the winter road maintenance on road users' safety. In this study, a highway net work of approximately 1250 lane-miles in four different states (New York, Illinois, Minnesota, and Wisconsin) were selected randomly with the cooperation of the authorities in each state. Data on road characteristics, traffic volumes, snow and ice control operations, and traffic accidents in the four states have been assembled from two winter seasons in New York and one winter season (1990-91) in Illinois, Minnesota, and Wisconsin. Detailed traffic analysis and adjustments were performed to arrive at estimates of hourly vehicle miles of travel 12 hours before and 12 hours after each sub-event$\\sp6$. Traffic accident data were similarly analyzed hour by hour and results reported by hourly accident rates. A statistical analysis was performed to evaluate the significant of traffic accidents occurrence change from before to after winter road maintenance operations. Also, a cost-benefit analysis was performed to compare direct costs of winter road maintenance operations with its direct benefits (accidents reduction and road users' savings). ftn$\\sp6$A sub-event in this study is the winter road maintenance operations conducted by the highway department to counteract the snow and icy conditions on one testing section in the respective area during any one snow storm.