Model of speed limit of expressway in snow based on variable road friction

Snowfall affects driving safety by causing changes in roadway surface that results in traffic accidents. Road friction is directly related to the amount of snow and the intensity of melt events on the road surface. Moreover, passing vehicles compresses the snow, sometimes even to ice, which impairs driving safety more seriously. Based on the fact that friction coefficient of road surface on different conditions such as the above-mentioned, this paper provides a method for calculating a safe speed limit in snowy days, taking into consideration the road parameters, visibility, and snow coverage and compression intensity. A Co-Simulation of CarSim&Simulink is established to simulate driving conditions on a snowy road, with stopping-sight distance model and sideslip model introduced. Taking braking distance and lateral offset as evaluation criteria, this paper analyzes the simulation results to verify the reliability of the proposed calculating method, and offers speed limit strategies for safe driving on highways in snowy days.