Connected vehicle-based simulation of variable speed limit effects on highway mixed traffic flow

With the rapid development of connected vehicles (CVs) technology, variable speed limit (VSL) control based on CVs has gradually become a practical application on highways. This paper aims to thoroughly investigate the effectiveness of VSL control in mixed traffic flow on highways based on CVs. First, a cellular automaton (CA) model for multi-lane mixed traffic flow on highways was developed, incorporating the deterministic driving behaviors of CVs and considering the characteristics of CV communication, including the heterogeneous speed limits. Then, we systematically explore the influence patterns of the penetration rate of CVs, traffic density, and the strictness of speed limits on the characteristics of mixed traffic flow, and interpret the mechanism of CV speed regulation from the perspectives of traffic capacity and critical density. Finally, regression equations for the fundamental parameters of mixed traffic flow are fitted based on simulation data, quantitatively revealing the regulatory mechanism of CVs on mixed traffic flow. The results show that: (1) increasing the penetration rate of CVs can significantly improve traffic efficiency, effectively suppress traffic oscillations, and simultaneously reduce traffic congestion and fuel consumption; (2) the effectiveness of CV speed limits is closely related to road spatial resources, and only exerts significant regulatory effects under conditions of sufficient longitudinal space; (3) there exists a synergistic effect between CV speed limits and penetration rate, jointly influencing the VSL effectiveness in mixed traffic flow. This work validates the effectiveness of CV-based VSL control and provides theoretical support and practical guidance for highway traffic management in connected vehicle environments.