Comparing the Safety and Mobility Benefits of Alternative Winter Road Maintenance Standards

Abstract

In countries like Canada, driving conditions can be significantly deteriorated by adverse winter weather conditions, such as ice and snow storms. To reduce the negative effects caused by inclement winter weather conditions, winter road maintenance (WRM) services are implemented by transportation agencies to restore road surfaces to bare conditions and provide safer driving conditions. WRM operations are commonly guided by a set of level of service (LOS) standards that specify the minimum level of service to be achieved for the different classes of highways. Higher highway classes receive higher levels of WRM service. However, WRM activities are costly, incurring both significant monetary costs and negative environmental effects. This research was motivated by the introduction of a new highway class - Urban Freeways (UFW) - in the province of Ontario’s highway classification system for winter road maintenance. UFWs include highways with winter average daily traffic volumes greater than 100,000 vehicle/day; they receive the highest WRM level of service. The substantial direct and indirect costs associated with winter road maintenance have stimulated strong interest in quantifying the safety and mobility benefits of upgrading level of service to the new UFW class. This research presents the findings from a field study aimed at comparing the winter road maintenance performance of alternative maintenance standards, and their impacts on safety and mobility. The new UFW class was introduced as a pilot study on four highway sections located in Central and Eastern Ontario, in the 2018-2019 winter season. A statistical analysis of the field test data found that bare pavement regain time was reduced by 40%, while salt usage increased by 139%, after implementing the upgraded winter road maintenance standard. A subsequent analysis was conducted to estimate the expected safety and mobility benefits due to the upgrading of the service standard, providing the critical information needed to make a decision on formal adoption of this new standard in future winter seasons. The analysis results conclude that highways with more severe weather conditions are iv expected to obtain more safety and mobility benefits. Moreover, traffic exposure is the decisive factor of the safety and mobility benefits gained from implementing the new UFW class when highway sections are having similar weather conditions. The monetized safety and mobility benefits, in combination with the additional costs of implementing the Urban Freeway class, could also be used to determine the optimal winter average traffic volume threshold for the Urban Freeway class. While the findings and conclusions of this thesis are only relevant to the study area where the tests were conducted, the underlying methodology can be applied by other jurisdictions that are facing the same problem.