Arterial Signal Timing Optimization Using P~ER II-87 BY EDMOND CHIN-PING CHANG, CARROLL J. MESSER, AND RENE

P is the acronym for the Progression Analysis and Signal System Evaluation Routine. PASSER II was originally developed by the Texas Transportation Institute (TTI) for the Dallas Corridor Project. The Texas State Department of Highways and Public Transportation (SDHPT) has sponsored the subsequent program development on both mainframe computers and microcomputers.’ The theory, model structure, methodology, and logic of PASSER 11 have been evaluated and well documented. PASSER II is widely used because of its ability to easily select multiple-phase sequences by adjusting the background cycle length and progression speeds to find the optimal timing plans, such as cycle, green split, phase sequence, and offsets, that can efficiently maximize the two-way progression bands.’ PASSER H-87 is the most recent version of the PASSER II program. Its version 1.0 was completed as part of the Texas HP&R 2-18-86-467 study, “Enhancements to PASSER II-84;’ by the Texas Transportation Institute of the Texas A&M University System. This new version was designed to be readily used by traffic engineers and transportation professionals to optimize or evaluate isolated intersection or coordinated arterial system operations of up to 20 signalized intersections. PASSER II-87 combines the updated PASSER 11 program; advanced analysis procedures similar to, but beyond, those used in the 1985 Highway Capacity Manual; and the latest microcomputer technology. Three applications can be made: (a) isolated intersection evaluations, (b) progression signal timing optimization, and (c) “existing” timing evaluation or “simulation” evaluation. The program assumes the isolated evaluation as the default operation if the input data pertain to only one intersection. On the other hand, the program will provide the progression analysis if the input data file includes more than one intersection. In the progression operation, PASSER II-87 seeks to maximize two-way bands and minimize signal delay based on the combination of traffic volumes, saturation flows, and minimum phase times under the given cycle length range. For successful program analysis, traffic turning movements and approach saturation flow rates are needed. Minimum phase times for each movement must also be provided. PASSER II-87 can optimize the signal phasings ranging from the simplest twophase operations to the most complex, variable sequence, multiphase arterial coordination. The signal phasings are selected on a “permitted” or “allowed movement” basis. Up to four possible arterial phasings are permitted at any one intersection, whereas each cross street can have only one of four possible phase sequences. In addition to the normal permitted or protected left-turn phasing treatments, it can also analyze the complicated permitted/protected or protected/permitted combined phase left-turn sequences. Because the PASSER II-87 system employs advanced highway capacity analysis technology, the system may also be used as a complete traffic planning and capacity analysis tool if the traffic volumes, saturation flows, intersection geometries, and existing signal timings are known.3