Development and application of control strategies for signalized intersections in coordinated systems

Modern controllers permit traffic signals in coordinated systems to operate as pretimed, semiactuated or fully actuated to improve the traffic performance at the particular intersection or over the total system.  Criteria were established for selecting the type of control, and timing strategies were developed for signals in coordinated systems.  The proposed strategies were evaluated through simulation on 14 representative real-world arterials and grid networks.  Based on the analysis of the simulation results, guidelines were formulated to assist practicing traffic engineers in selecting the most appropriate control strategies at specific intersections in coordinated signal systems.  The guidelines were then applied to select the type of signal control at several intersections in the City of Los Angeles.  The results from before and after field studies indicate that the recommended control strategies improved traffic performance, and the study guidelines can be used as an operating tool for traffic signal management.