EXPLORATION OF TRAFFIC PHASES

Abstract

Without considering the traffic stream evolution, conventional traffic stream diagrams may provide incomplete information for real-time traffic management and control applications. This study aims to add evolutionary information into the traffic stream diagrams by ordering chronologically the paired-traffic parameters and to explore the emerged traffic phases and their transitions. The flow, speed, and occupancy raw data directly extracted from dual-loop detectors on freeway at various times of day are investigated. Our investigations show that traffic stream characteristics do exhibit various phases, including free-flow phase, synchronized-flow phase, and breakdown phenomenon-an unstable phase that plays a transitive role between free-flow phase and synchronized-flow phase. Our exploration of traffic phases with consideration of traffic stream evolution has shed some light on the development of advanced real-time traffic management/control strategies.