University of Vermont Transportation Research Center

Document Type


Publication Date



Roadway snow and ice control (RSIC) serves a vital public safety function and reduces the economic losses caused by winter weather. The effectiveness and efficiency of the RSIC response requires that managers have access to meaningful performance measures that accurately capture the roadway conditions throughout the network. Performance measurement metrics provide a baseline for evaluating agency operations and improve agency transparency. Effective longterm performance measures can provide quality assurance of staff productivity, equipment allocation, and process evaluation. Effective short-term performance measurement can provide quality control for real-time productivity improvement and efficient resource use. The primary performance measures for RSIC programs by state DOTs are 1) operating speed recovery time and 2) time to achieve bare pavement. There is a continued need for objective, outcome-based performance metrics for RSIC operations. The overall goal of this project was to develop new performance measures intended to improve the performance of RSIC activities by the VTrans fleet and a plan for how they could be implemented full-scale. Two specific objectives were planned by the research team at the University of Vermont Transportation Research Center to achieve this goal: • Develop a long-term, seasonal “time-to-normal” measure utilizing readily available speed data • Pilot-test a short-term measure utilizing imagery data collected and processed in real-time to compare roadway conditions in front of, and behind, an active RSIC vehicle In this study, a new long-term performance measure, the Average Distribution Deviation (ADD), was developed to measure changes in the distribution of vehicle speeds after winter weather events. Measuring the recovery time for the entire distribution of vehicle speeds, rather than the recovery of a single measure like the mean speed, provides a more comprehensive assessment of RSIC performance. A thermal imaging video system was pilot tested as a short-term measure of RSIC performance. These two long- and shortterm RSIC performance measures provide distinct and complimentary assessments of RSIC operations. The long-term ADD performance metric can be used to measure the time to complete RSIC operations on a storm-by-storm or seasonal basis, while the short-term, video-based performance measure is designed to provide near instantaneous feedback that can be used to inform the rate of application of chemicals by, and routing of, snow and ice control vehicles.