ALBERT GROVER & ASSOC. 1 -2003 - Laserfiche WebLink

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Mr. Dowling Tsai January 10, 2003 Page 7 locations. AGA will investigate the potential use of such phasing on project arterials. Our experience has been that such phasing can help optimize signal timing at selected locations. Lead/lag phasing is very helpful in minimizing delay and allowing for the use of shorter cycles. Primarily, it provides for wider bands and allows for progression with both thru and left turn movements. Without lead/lag phasing, left turns are typically NOT coordinated and queues will be longer, so lead/lag phasing can help when pockets are short. PASSER is the best program to indicate when lead/lag phasing may be appropriate. AGA's experienced staff will carefully review the actual need for lead/lag phasing at minor intersections and will minimize its usage for better efficiency of actuated operation. Side Street Delay: Because AGA's staff has prior experience working for cities, we understand the sensitivity in coordinating signals at minor cross streets. The side street delays xvill be kept to a minimum by using double cycling xvhere feasible. Our field review indicated that while a significant percentage of project signals are multi-phase, there are many two-phase signals. This requires special attention for maintaining short cycles and minimizing side street delay. Local Factors: Knowledge of key local factors, such as the location, operating hours and peak flow conditions related to periods of high commute traffic, various area schools, shopping malls, etc., are all very important in preparing timing plans. AGA's knoxvledge of such local factors, combined with input from the City, will greatly enhance our ability to develop the most appropriate timing plans. Additionally, attention must be given to any crossing arterials that are not included in this project but that already are, or may be in the future interconnected and coordinated when establishing logical break points on project arterials, if such break points are required. Consideration will also be given to local streets when developing the cycle lengths, to avoid unnecessary delays to local residents and pedestrians. Timing Plan Deliverables: Based on our experience and area knowledge, AGA proposes to prepare a.m., mid-day and p.m. peak hour timing plans. Additional timing plans will be developed based on various assumptions relative to non-recurrent congestion. These plans will be stored in a database format. Time-of-day schedules (the appropriate start time for each plan) will be developed based on field observations, 24 hour traffic counts and input from City staff. After initial development of the signal timing plans, they will be submitted to the City for review. Plans will be revised as required, and controller timing sheets will be developed. These revisions are typically minimized because AGA will already have reviewed and manually optimized all timing plans. Time-space diagrams xvill be prepared for all timing plans, to aid in the review process and to graphically document the finalized timing parameters. After City review and acceptance of AGA de,loped time-space diagrams, the coordination timing plans will be installed in the City's central control system and