Roadside intelligence for flow control in an intelligent vehicle and highway system

Abstract The paper reports a design of the flow control function of the highly automated Intelligent Vehicle Highway System that we call SmartIVHS. Work on the architecture, design, experiments, and performance evaluation of this system has been going on for several years. SmartIVHS achieves high throughput and safety through a three-layer control hierarchy distributed between vehicles and infrastructure. Previous work was devoted to the two lowest layers: automatic control of individual vehicles based on on-board sensor information, and coordination of maneuvers by neighboring vehicles. This paper considers the third or ‘link layer,’ which controls the vehicle stream based on aggregate traffic variables. The link layer controller is implemented by roadside computers. The two lowest layers are implemented by vehicle computers. The paper is divided into three parts. First, a structure of the link layer controller is proposed. Its objectives are to maximize throughput and to maintain smooth traffic flow despite disturbances, including lane-blocking incidents. The objectives are met by proper guidance of the speed and lane-changing behavior of vehicles. Second, a macroscopic flow model of SmartIVHS traffic is proposed. A novel feature is the explicit incorporation of the effects of lane changes, entrances, and exits. The program SmartLink simulates this model. Third, performance of the link layer controller is evaluated using SmartLink. The results suggest that the controller maximizes throughput and minimizes delay in the presence of disturbances and incidents.