Determination of Timings in Signal Systems with Traffic-Actuated Controllers

Abstract

Many traffic control systems on urban arterials and grid networks include signals with actuated controllers. However, commonly used signal timing computer programs have been designed for fixed-time signals and cannot directly optimize the timing of coordinated actuated signals. Users have to apply techniques designed for pretimed signals and then translate the optimal fixed-time plans into settings for the actuated controllers. The development of improved procedures for applying the MAXBAND, PASSER, and TRANSYT-7F timing programs to arterials and grid networks with actuated controllers is described. These procedures determine the yield points, force-offs, and maximum green times from the fixed-time plans on the basis of simple analytical relationships. The proposed procedures were applied on 14 representative real-world arterials and grid networks with different characteristics, and their performance was evaluated with the NETSIM microscopic simulation model. The results indicated that the proposed procedures improved traffic performance compared with the commonly used approaches that directly use the optimal fixed-time splits and offsets to set the actuated controller settings. Based on the study findings, guidelines were formulated and documented for timing coordinated actuated signals.