Regional TSP Location Study Task 8B (March 2002)
Total Page：16
File Type：pdf, Size：1020Kb
Regional Transit Signal Priority Location Study—Phase II, Model Simulation Signal Timing Optimization Results (Deliveralbe 8B) March 8, 2002 Prepared for: Regional Transportation Authority Chicago, IL Prepared by: Civiltech Engineering, Inc. 450 E. Devon Ave., Suite 300 Itasca, IL 60143 (630) 773-3900 FAX (630) 773-3975 Regional Transit Signal Priority Location Study, Phase II Simulation Signal Timing Regional Transportation Authority, Chicago, Illinois Optimization Results INTRODUCTION This report will summarize the information presented at the Signal Timing Optimization Workshop held on December 11, 2001. At the workshop, the methodology utilized to optimize each of the systems was reviewed and the results of the optimizations were presented. EXISTING OPERATION Existing traffic signal timings were obtained from the maintenance agencies for each system. These timings were used to analyze the existing intersection operation and level of service and to develop time-space diagrams which represent the existing system operation. Existing timings were obtained for all of the City of Chicago signals except at Milwaukee Avenue/Elston Avenue/Melvina Avenue and at Archer Avenue/Lavergne Avenue. For the signals not owned by the City of Chicago, timings were only obtained for those intersections which were part of a traffic signal interconnect system since the timings could be downloaded by the maintenance agency via a dial-up connection. For those signals which are not part of a system, none of the other agencies keep copies of the intersection timings in their office and none had the manpower available to obtain copies from each controller cabinet. A total of twelve time-space diagrams were developed using the TS-PP-Draft software and the existing timing data collected. Existing time-space diagrams were not developed for the following five systems: Dempster – 3 Timings only available for 3 of the 10 signals. Grand Avenue No timings available. Lake Cook Road No timings available. Washington Street Existing timings are being used as optimized. Western Avenue 2 & 3 City to provide timings to be used for optimized. Only a portion of the following systems were included in the diagrams: 127th Street/130th Street Wood Street to Throop Street Milwaukee Avenue Devon Avenue to Lawrence Western Avenue – 4 115th Street to 101st Street 87th Street Ashland to Cicero These diagrams have been included in Appendix A of this report. It should be noted that for many of the systems, cycle lengths varied within the system. The software was unable to depict the green bands so we have manually depicted them; however, for those systems, progression through the system is generally quite poor. ITC Team Page 1 March 8, 2002 Regional Transit Signal Priority Location Study, Phase II Simulation Signal Timing Regional Transportation Authority, Chicago, Illinois Optimization Results OPTIMIZATION METHODOLOGY In the Signal Timing Optimization Methodology report dated September 10, 2001, a detailed review of the signal timing optimization software was presented and the methodology to be used for this study was described in detail. Briefly, that methodology involves the following steps: Step 1: * Signal2000: Analyze the existing intersection operation. Step 2: * Signal2000: Optimize intersection splits and determine optimum cycle length based on intersection delay. * NOSTOP: Determine optimum cycle length based on 2-way progression. * TRANSYT-7F: Determine optimum cycle length based on system performance. * Review the results of these three analyses and choose a system cycle length. Step 3: * Signal2000: Utilizing the selected system cycle length, the intersection was reanalyzed and splits were again optimized. Step 4: * PASSER II: The intersection splits were held constant and the system offsets were optimized to maximize 2-way green bands. * TRANSYT-7F: The output from PASSER II was utilized as a starting point and the offsets were further optimized to account for queues along the system. Step 5: * TS-PP-Draft: Input optimized splits and offsets to develop time-space diagrams for each system. BASIC ASSUMPTIONS In order to assure consistency in the optimization of the seventeen systems, certain assumptions were necessary. Some were blanket assumptions covering all systems and others were specific to a single system. Blanket Assumptions: 1. Each system will be controlled by a single master controller. A single cycle length was used for all signals within that system. 2. Signals within a system are either all fully-actuated or all fixed time. 3. Only one iteration each of PASSERII and TRANSYT-7F were made. 4. Cycle lengths between 75 and 150 seconds were analyzed for fully-actuated systems and between 65 and 130 seconds for fixed time systems. ITC Team Page 2 March 8, 2002 Regional Transit Signal Priority Location Study, Phase II Simulation Signal Timing Regional Transportation Authority, Chicago, Illinois Optimization Results System-Specific Assumptions: 1-1 127th Street/ 130th Street Fully-actuated operation used. 1-2 Dempster Street –3 Fully-actuated operation used. 1-3 Grand Avenue Fully-actuated operation used. 2-1 Milwaukee Avenue - 2 Fixed time operation used. The Holbrook and Elston/Melvina intersections were combined into a single intersection. Austin/Ardmore/Milwaukee is a 6-leg intersection. Ardmore analyzed as ped scramble phase. 3-1 Lake Cook Road Fully-actuated operation used. New NB entrance ramp to I-294 not included because it was not open at time of traffic counts. 3-2 Western Avenue – 4 Fixed time operation used. 4-1 Dempster Street – 2 Fully-actuated operation used. 5-1 Cermak Road – 1 Fully-actuated operation used. 6-1 Archer Avenue Fixed time operation used. 6-2 Washington Street Existing timings used as optimized. 7-1 Cicero Avenue – 2 Fixed time operation used. 8-1 Irving Park Road Fixed time operation used. Lincoln/Damen/Irving Park and Clark/Irving Park include ped scramble phases since they have more than 4 legs. 8-2 Western Avenue – 2&3 City of Chicago will provide timings recently developed by their staff. Diagram included in this report reflects optimizations completed by Civiltech. 9-1 87th Street – 1 Fully-actuated operation used. 10-1 Chicago Avenue Fixed time operation used. 11-1 Halsted Street Fully-actuated operation used. 12-1 MLK Drive Fixed time operation used. Ellsworth/51st/MLK and Best/60th/MLK include ped scramble phases since they have more than 4 legs. OPTIMIZATION RESULTS With the completion of the optimization for the systems, time-space diagrams were again developed using TS-PP-Draft to visually depict the results. Some minor adjustments to offsets were made where it appeared that the adjustments would help progression through the system. These diagrams have been included in Appendix B. A comparison between the width of the existing and optimized green bands for each direction during each peak hour was made. These have been summarized in tables which are included in Appendix C. Since most of the existing systems had never been optimized for end-to-end progression was done for this project, improvement in green band width and progression through the system was quite evident. ITC Team Page 3 March 8, 2002 Regional Transit Signal Priority Location Study, Phase II Simulation Signal Timing Regional Transportation Authority, Chicago, Illinois Optimization Results For each of the systems which were optimized, a comparison between the existing level of service and the optimized level of service was also made for two separate intersections. The level of service (LOS) depicts how well the overall intersection or an intersection approach is operating and is represented by both a letter and a number. The letters range from “A” to “F” with “A” representing relatively free flowing traffic conditions and “F” representing traffic that is essentially grid-locked. The number associated with those letters represent the seconds per vehicle of average control delay for each approach or for the intersection as a whole, as follows: LOS Control Delay per Vehicle (s/veh) A [10 B > 10-20 C > 20-35 D > 35-55 E > 55-80 F > 80 Tables summarizing these Levels of Service for each of the systems for which optimized timings were developed are included in Appendix D. It should be noted that for a majority of the intersections evaluated, the delay actually increased from the existing condition to the optimized condition. This is primarily due to the fact that, in order to develop a green band through an entire system, particularly the longer systems, it is necessary to increase cycle length. When the cycle length at an intersection is increased, in most cases the delay also increases. This is displayed graphically in the graph below: ITC Team Page 4 March 8, 2002 Regional Transit Signal Priority Location Study, Phase II Simulation Signal Timing Regional Transportation Authority, Chicago, Illinois Optimization Results SUMMARY In conclusion, with the exception of Western Avenue– 2 & 3 and Washington Street where optimized timings already existed, the entire limits on each of the routes were treated as a single system and optimized timings were developed. These results will be the basis for the “optimized” scenarios of the VISSIM modeling. It should be noted, however, that in actuality many of these systems would likely be broken into two or more systems if they were to be interconnected and optimized. In addition, once optimized timings are developed for a system, they are implemented and fine-tuned in the field through observations of actual traffic movements.