Dynamic Traffic Control System for Over-Saturated Traffic: Comparison of Adaptive Control Strategies

Abstract

This study developed a dynamic traffic control system designated as Dynamic Intersection Signal Control Optimization (DISCO). DISCO considers the entire Fundamental Diagram of traffic flow, which is essential for controlling congested and transient traffic. As a dynamic model, DISCO works with time-variant traffic patterns and derives dynamic adaptive timing plans. In this study, we applied DISCO to a congested network in Hong Kong and compared the performance of various control strategies enabled by DISCO. The results showed that DISCO outperformed the existing plans by more than 50% in terms of overall delay reduction. Moreover, DISCO performed best under the most flexible control scheme of variable green no cycle strategy. DISCO shows promise as a new approach for demand-responsive traffic control. Introduction Recently, Lo (1999, 2001) developed a cell-based dynamic signal control formulation designated as Dynamic Intersection Signal Control Optimization (DISCO), DISCO encapsulates the Cell-Transmission Model (CTM) (Daganzo, 1994, 1995) which makes it a suitable platform for modeling dynamic traffic. We applied DISCO to a range of demand scenarios to demonstrate its ability (Lo, 1999, 2001). The results were promising. In this paper, we focus on comparing the performance of various control strategies enabled by DISCO for over-saturated traffic conditions. The results showed DISCO performed best under the most flexible control scheme of variable green no cycle strategy. I Associate Professor. Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong; phone: (852) 2358-8742; Fax: -1534; cehklo@ust.hk Professor, Department of Civil and Structural Engineering. Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong