Winter Travel Speed Data as Performance Measures for Winter Operations

The highway agencies in snowy regions are constantly looking for new approaches for winter maintenance operations. These approaches include a search for new equipment, new materials, or improved methods for winter operations. Improved methods and materials could provide safer driving conditions with improved mobility during winter storms. The use of performance measures to measure the effectiveness of winter maintenance operations is critical to highway agencies to select the best methods. Several performance measures for winter maintenance were developed in the past based on material usage, equipment usage, and other input-based quantities. However, the traveling public is always keen on outcome-based quantities such as travel time, travel speed, and travel safety. Since vehicle speeds are significantly reduced during winter storms, performance measures based on traffic speeds seem to be good indicators for winter maintenance operations. In this study, average and minimum traffic speed during winter events are studied as a case study to use as performance measures for winter maintenance operations. Traffic-speed based performance measures were obtained by analyzing archived speed data of University of Maryland’s Regional Integrated Transportation Information System (RITIS). RITIS stores thousands of traffic speed data from multiple sources and archived them in their databases. Data was analyzed for 2012-2013 winter season for I-96 and US-23 roadways in Livingston County, Michigan.