Abstract: Based on the analysis of vehicle driving behaviors and accidents, a cellular automaton (CA) simulation model of longitudinal slope curve on mountain freeway with the possible occurrence of traffic accident was established. The model was preliminarily validated via the comparisons between the accident rates in simulation experiments and that in actual statistics for the concrete roads. The possible schemes were determined by setting the different values of road geometric linear parameters. The nonlinear behaviors of traffic flow were simulated and the accident probabilities were obtained. The relations among the accident rate and the parameters’ values were discussed. The results of the example show that the conclusion that the accident rate can be declined by increasing the curve bend radius, reducing the curve length, increasing the curve superelevation, and reducing the speed upper limit was proved again; the values of designing parameters can be optimized and the reasonable speed upper limit value can be set in traffic management according to the proposed CAM and the concrete project. The goal of ensuring the traffic safety and decreasing the investment can be realized.

Key words: traffic simulation, traffic accident probability, cellular automaton model (CAM), mountain freeway, longitudinal slope curve