Evaluation of New Jersey Route 18 OPAC/MIST Traffic-Control System

OPAC-2, was a simplification of the OPAC-1 algorithm. A rolling horizon concept was later introduced in the algorithm. This concept is used mainly by operations research analysts in productioninventory control. The algorithm was renamed ROPAC. At this point the algorithm was still an off-line program. The ROPAC program was reorganized for implementation in real time and called OPAC-RT Version 1.0. This version was restricted to two-phase operation. Version 2.0 could simulate eight-phase timing but could control only the four major (through) phases. These two versions were field-tested at three isolated intersection sites (2). The field results indicated that OPAC performed better than fully actuated signals, especially at higher demand levels. Version 3.0 of OPAC-RT incorporated several enhancements that are important for efficient operation and that make the algorithm workable for situations other than isolated intersections. Enhancements included optimization of all eight phases, phase skipping, dynamic speed calculations, and a platoon identification and modeling algorithm that provides a coordination mechanism for adjacent signals. The New Jersey implementation of Version 3.0 provided the necessary site for its evaluation.