Combined Variable Speed Limit and Lane Change Control for Truck-Dominant Highway Segment

Abstract

Traffic demand of trucks is rapidly increasing on highway networks, which harms highway traffic mobility, safety and the environment. Variable speed limit (VSL) control is considered to be able to improve the traffic condition in truck-dominant highway segments. However previous research reported rather mixed effects of VSL controller on traffic mobility. While some studies reported improvements in travel time due to the use of VSL control, others reported either no improvement or small deterioration in travel time. In this paper, we demonstrated that the lack of improvement on travel time is due to lane changes that are taking place close to the bottleneck leading to severe capacity drop. We developed a combined lane change and VSL control strategy that recommends lane changes in advance to relief capacity drop in addition to VSL. Microscopic Monte-Carlo simulations on I-710 freeway with high truck demand were used to demonstrate that this combined control strategy is able to generate consistent improvements with respect to travel time, safety and environmental impact under different traffic conditions and incident scenarios.