Adaptive Signal Control at Isolated Intersections

Abstract

The effectiveness of conventional traffic‐actuated control deteriorates rapidly as traffic volume increases. This problem can be alleviated through adaptive control. By monitoring vehicular movements and identifying the most likely short‐term future flow patterns, adaptive control adjusts signal timings in an attempt to optimize signal operations. Both field test and simulation analysis have shown that adaptive control has the potential to provide improved signal operations. Further research is needed to develop a versatile and effective adaptive control logic that can replace traffic‐actuated logics. The primary objective of this paper is to discuss the issues and research needs concerning the development of adaptive control logics for applications at isolated intersections. The discussions are focused on the information needs for adaptive control, the selection between a binary choice process and a sequencing process for timing adjustment, and future research needs. To be widely applicable, an adaptive control logic needs a vehicle‐monitoring system that can provide reliable information and facilitate simultaneous use of real time and advance information for decision making.