Speed Limit Zone Length Control Strategy under Mixed Traffic Flow Environment: An Approach Considering Variable Speed Limit and Lane Change

Abstract

The rapid advancement of car networking and autonomous driving technologies allows for more sophisticated active traffic management. Several studies have demonstrated variable speed limit (VSL) and lane change (LC) control to have the potential to smooth traffic flow and improve bottleneck throughput and road safety. However, VSL control zone length has lacked further exploration as a control parameter. This paper proposes a novel human driving vehicle (HV) discretionary lane-changing model that considers the human driver’s lane change expectation and incorporates driver types and random behaviors to model mixed traffic flow, which more realistically reflects the behavioral differences between connected and autonomous driving vehicles (CAVs) and HVs. Moreover, a multisection cell transmission model (CTM) VSL strategy is adopted to analyze traffic performance under different VSL control zone lengths and CAV penetration rates in the simulation, which provides a valuable reference for selecting the optimal VSL control zone length. Simulation results show that VSL with LC control improves traffic safety between the VSL control zone and the bottleneck. Still, under high traffic demand, control measures may negatively affect the section further upstream. The research also discovered that when control measures are activated, the increase in CAV penetration rate does not necessarily improve traffic efficiency, but it makes the traffic flow more harmonious.