Lane-changing control with balancing lane flow at freeway merge bottlenecks in a connected vehicle environment: Application of a PID controller

A merging section on a freeway is a typical bottleneck where congestion easily occurs due to interference caused by vehicles entering the mainline from the ramp. To achieve higher speeds and/or yield to merging vehicles, drivers on the mainline often change lanes while continuously examining the circumstances ahead that are within their sight. This individual lane-changing behaviour is somewhat myopic and could cause an imbalance in lane use, resulting in earlier onset of congestion and a more severe capacity drop than with balanced lane use. This study proposes a feedback-based lane-changing control strategy that balances lane flow at merge bottlenecks to mitigate capacity drop under a connected vehicle environment. The proposed Proportional-Integral-Derivative feedback controller examines the traffic state of the inner lanes and systematically governs the number of lane-changing vehicles to prevent possible excessive disturbance. The proposed strategy is evaluated using microscopic simulation. For the hypothetical network, the strategy reduces the imbalance in lane flows and improves discharge flow rate as well as travel time. For the real-world network, the strategy can also effectively relieve congestion in a possible scenario of connected automated vehicle adoption. These results indicate that the proposed strategy can improve flow efficiency for high-volume traffic.