ALBERT GROVER & ASSOC. 1 -2003 - Laserfiche WebLink

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Mr. Dowling Tsai January 10, 2003 Page 5 Experience is a key factor in determining the appropriate technical approach for preparing the signal timing plans. AGA staffs experience, not only in conducting similar signal timing projects but also in developing the computer scftware currently used by other consulting firms and government agencies to perform the technical analyses required to complete projects of this type, is invaluable for this effort. Our experience is not only in using software, but more importantly in providing engineering of timing plan development. The various softxvare programs available are incapable of providing a workable timing plan independently, but are invaluable "tools" for an experienced Traffic Engineer to utilize in developing a workable timing plan. These various "tools" are used by the experienced Traffic Engineer in a manner similar to how a gifted carpenter uses hammers, chisels, saws, etc. When hiring a carpenter to do remodeling, his experience and ability to utilize the most appropriate tool properly is far more important than the type of hammer he selects for any given task. Software programs are merely the "hammers and saws" of our trade. AGA's approach to several key components of the signal timing plan development process is detailed in the following sections. Field Data Inventory: In the development of signal timing plans, it is imperative to have appropriate intersection geometrics, signal phasing, arterial link speeds and knowledge of closely spaced intersections. For this project, the field data inventory will be overseen by AGA's Timing Plan Development Task Manager so that the prevailing conditions in the project area are better understood. Also, AGA proposes to field measure link speeds using the floating car technique. This field measurement is crucial for determining proper and effective coordination between signals. Our practice is to develop progression timing for prevailing speeds but not to significantly exceed the posted speed. This subtask will also aid in determining if coordination between widely spaced intersections can be achieved. Saturation Flow Rate Measurements: One of the key parameters that plays a pivotal role in developing effective signal timing is saturation flow rate. The saturation flow rate, expressed in vehicles per hour of green per lane, is affected by factors such as number and width of lanes, cross gutters and street grade, driver attitude, vehicle mix, lack of left turn pockets, pedestrians, transit and area type. AGA proposes to field measure saturation flo~v rates at sample locations. These measured values are then used to determine accurate capacity values, which is key to deve!oping efficient signal progression. Signal Timing Software: As previously noted, various signal timing analysis and simulation software programs and/or combinations of programs can be used for this project. Such programs include WEBSTER, PASSER, TRANSYT, and SYNCHRO. The most appropriate method depends upon various factors, including xvhether minimization of system delay or optimization of arterial progression is most important to the City. WEBSTER, (WEbster Based Signal Timing Evaluation Routine) is a program for developing/analyzing cycle lengths at individual intersections. WEBSTER is based on the Year 2000 Highway Capacity Manual and can be 'trged for traffic impact analyses and signal timing development as well as CMP monitoring. PASSER provides arterial