Traction Performance of Transit and Paratransit Vehicles on Ice and Snow Surfaces

Abstract

In this study, the traction performance of transit and paratransit vehicles was evaluated on snow and ice surfaces. Field tests were conducted in Fairbanks, Alaska, using three types of vehicles: 1) a 41-passenger transit bus; 2) a 32-passenger transit bus, and 3) a 9-passenger paratransit vehicle. Each vehicle was tested for different combinations of tire types that included highway tires, snow tires, studded-siped tires, highway 3-rib tires, all-season tires, and snow siped tires. Winter traction performance was evaluated using a number of tests that included stopping distance, starting traction, hill-climbing, cornering, and controllability. Results indicate that winter traction performance is significantly influenced by vehicle type, tire combination used, and the road surface condition (compacted snow or ice). Research findings and recommendations for appropriate tire combinations that are most suitable for winter traction are presented. Introduction Winter traction performance of transit and paratransit vehicles has a direct impact on their safe operations during winter. In cold regions, transit and paratransit vehicle drivers suffer difficulties when driving on snow or ice surfaces, especially when starting, stopping, cornering, and hill climbing. The main reason for such difficulties is the reduced coefficient of friction between tire and road surface. The direct consequences are increased stopping distances, reduced acceleration ability (i.e. reduced starting traction), reduced maximum cornering speed (to avoid loss of control during cornering), decreased hill climbing ability, and loss of control with immediate stopping. lprofessor, Department of Civil and Environmental Engineering, Transportation Research Center, University of Alaska Fairbanks, Fairbanks, Alaska 99772 2Assistant Professor, Department of Civil Engineering, University of South Florida, Tampa, Florida 33620 3Associate Professor, Department of Civil and Environmental Engineering, Transportation Research Center, University of Alaska Fairbanks, Fairbanks, Alaska 99770.