Automated Phase Design and Timing Adjustment for Signal Phase Design

Abstract

In this paper we describe the design processes of human traffic engineers and the development of an automated system that solves the problem of timing adjustment in signal phase sequence design. Signal phase sequencing refers to the sequence of signal changes and the timing of each change for a system of traffic lights at an isolated intersection. In designing signal sequences, one must decide how much time to allocate for each phase of the sequence so that traffic can flow with a minimum of delay. Other automated phase design systems can generate an initial phase design, but if the initial design is not precisely correct, the timing sequence must be adjusted by hand. This paper presents TIMELY, an automated signal phase design generator that generates an initial phase design and automatically adjusts the timing if necessary. TIMELY uses an interactive redesign strategy which largely mimics that used by human experts. The system invokes a set of redesign rules (which we have dubbed the “Robin Hood” procedure), gathered from human experts, which tweak the phase design. The new design is fed back into a simulator and tested again. The process stops when we find that the average delay is not improved. We take the design from the previous step as our final design. An expert has verified the soundness of all of TIMELY's results.