Cellular automaton model for traffic flow under ice and snowfall conditions

A single-lane and a two-lane urban microscopic traffic flow models are developed under ice and snowfall conditions based on cellular automata. Drivers prefer to reduce speed and keep larger vehicle spacing for safety on ice and snowfall road. According to this phenomenon, this paper considers the cellular size and introduces speed factor and spacing factor which are different under different ice snowfall conditions. By numerical simulation, the curve diagram is obtained between velocity, density and flow in both normal and snow weather, and it analyzes the effects of different snow conditions on the traffic flow. It is found that the fluctuation range and level of vehicle speed in moderate snow is the maximum. Fundamental diagrams show that the ice and snowfall conditions have great influence on the critical density, maximum flow and other parameters. Metastable hysteresis phenomenon is not obvious, and the maximum of changing-lane frequency does not exist under ice and snowfall conditions.