A Cellular Automaton Model for the Keep-Right-Except-To-Pass Rule

This paper aims at examining the effectiveness of the Keep-Right-Except-To-Pass rule in different traffic conditions. In addition, the paper tries to explore a more rational traffic rule to reach a better balance between traffic flow and safety. To address the problem, we develop a two-lane cellular automaton model. In our model, we divide the vehicles into two categories according to their willingness to overtake and emphasize on the overtaking behavior of the vehicles based on the Keep-Right-Except-To-Pass rule. To test the rule, we check the relation between traffic density and traffic flow. And we find adopting the rule can raise the traffic flow by an average of 21.4% in light traffic and 24.8% in high traffic compared to not allowing overtaking. This means this rule of overtaking can improve the efficiency of traffic. Moreover, we develop our own Convert-Only-Once rule on the basis of our model. And simulation proves that compared to the Keep-Right-Except-To-Pass rule, our new rule can boost the traffic flow by 14.3% and enhance the safety index K by 1.2%. Furthermore, we analyze the influence of the Coriolis force on our model when we adjust our model to the situation of driving on the left. In order to fit our model into an intelligent system, we exclude the influence of willingness to overtake and make some adjustment to a certain parameters. And the conclusion is similar, Convert-Only-Once rule can still hold 8.4% more traffic flow than the Keep-Right-Except-To-Pass rule.