Analysis of mixed traffic flow with different lane management strategy for connected automated vehicles: A fundamental diagram method

This paper proposes a fundamental diagram of the mixed traffic flow for multi-lane road segments with connected automated vehicles (CAVs) dedicated lanes based on a flexible and efficient lane management strategy for CAVs. First, two lane management strategies of CAVs dedicated-HDVs lane strategy (i.e., C-H strategy) and CAVs dedicated-Mixed lane strategy (i.e., C-M strategy) are introduced. The more efficient C-M strategy is chosen based on the characteristics of the two strategies, and the five stable states under this strategy are analyzed. Second, different car-following modes in mixed traffic flows are analyzed, and general fundamental diagrams for homogeneous and mixed traffic flows are derived based on car-following models. Then, the stabilized traffic conditions are derived based on the traffic flow characteristics in the five stable states. A fundamental diagram model for the multi-lane road segment with CAVs dedicated lanes is developed based on the general fundamental diagram, and some properties of the fundamental diagram are derived. Finally, the impacts of different numbers of dedicated lanes and traffic conditions on the traffic volume and capacity are analyzed based on the fundamental diagram, and the optimal settings of dedicated lanes for CAVs under different lane number scenarios are given. Numerical simulation results showed that: (1) there are five stable states for the traffic flow on the road segment under the C-M strategy; (2) properly setting up CAVs dedicated lanes can effectively improve the efficiency of road segments; (3) under the C-M strategy, for any CAVs dedicated lane setting scenario, the traffic capacity of the road segment shows a gradually increasing trend as the penetration rate of CAVs increases. (4) compared to the C-H strategy, the capacity of the road segment under the C-M strategy will be higher than the CH strategy when the CAVs penetration rate exceeds a certain threshold. Moreover, as CAVs penetration rate increases further, the advantages of the C-M strategy in terms of traffic capacity become more and more significant.