Microsimulation of Connected and Automated Vehicles with Integrated Variable Speed Limit and Lane Change control Revealed up to 44.62 Percent Reduction in Travel Time.
A Two-Lane Freeway Segment in Simulation was Evaluated to Test Integrated Variable Speed and Lane Change Control Strategies.
Integrated Variable Speed Limits and Lane-Changing Control for Freeway Lane-Drop Bottlenecks
Summary Information
Variable Speed Limits (VSL) and Lane-Changing (LC) control strategies are widely used strategies to relieve traffic congestion at bottlenecks, although with limited effectiveness due to mandatory LC maneuvers near bottlenecks, and extremely high traffic demand in some cases. This study proposed a Model Predictive Control (MPC), integrating VSL and LC strategies under a Connected and Automated Vehicle (CAV) environment, to maximize traffic efficiency through traffic state prediction, optimization, and appropriate strategy implementation. A hypothetical two-lane freeway section was considered for the simulations, with the assumption that a bottleneck forms as a result of an incident blocking the right lane.
METHODOLOGY
This study employed a traffic state prediction model, a traffic network performance optimization model, and implemented the MPC method on a microsimulation platform. Using information from CAVs, the average speed, traffic density, and flow rate were collected. Simulations were conducted under low, medium, and high traffic demands (1000, 2000, and 3000 passenger car equivalent[PCE]/hr/two lanes) with and without MPC. Three incident scenarios were tested: a minor incident lasting 10 minutes, a normal incident lasting 30 minutes, and an unresolved incident simulating a construction site or bottleneck.
FINDINGS
- The results demonstrated that the MPC method outperformed both the No Control and VSL-only control approaches, achieving reductions in travel time and exhaust emissions of up to 44.62 percent and 48.19 percent, respectively.
- The results without and with MPC indicated that, for medium demand (2000 PCE/hr/two lanes), the flow improved by 51.1 percent.
