2017-046 - Approving Addendum Nos. 1 and 2

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Santa Ana — Garden Grove Streetcar Project Traffic Study Addendum 2.4.2 Traffic Volumes and Geometric Configuration AM and PM peak hour intersection traffic volumes were referenced from the Year 2035 Streetcar Alternative 1 volumes contained in the Traffic Impact Assessment. Baseline intersection configurations were based on the geometrics assumed as part of the 2035 Streetcar Alternative 1. 2.4.3 Methodology and Significance Criteria Since the streetcar alternative would operate in shared traffic lanes, operation of TSP for the streetcar would affect traffic flows and capacity. Implementation of TSP atthe affected intersections would permit extended green phases (for streetcar movements) or shortened red phases (for all conflicting movements) by up to 20 seconds per intersection. Since the City -approved ICU methodology does not factor in signal timing or delay, the TSP analysis was first run using the HCM methodology. The HCM methodology (using the Synchro traffic software) was used to determine the increase in delays experienced by non -streetcar movements at each intersection, as well as the decrease in delays experienced by streetcar movements. The increase or decrease in delay on a movement -by -movement basis from the HCM analysis due to TSP was then utilized as the basis for a series of capacity adjustments within the ICU analysis at each intersection. Intersection movements that corresponded with streetcar movements (i.e., eastbound and westbound through movements) were given a capacity "credit" due to the increase in green time or shortened/truncated red time associated with a preemption event. The lane capacity for all other movements at the intersection during a preemption event were effectively decreased to reflect the shortened green time/increased red time given to allow the streetcar to pass. Detailed capacity adjustments are discussed in Section 3.4, Transit Signal Priority Impact Analysis. 2.5 Santa Ana Boulevard Station Relocation Analysis 2.5.1 Study Area The project is proposing a new street design concept that affects portions of the alignment on Santa Ana Boulevard from Raitt Street to SARTC. Affected Intersections 1. Santa Ana Boulevard/Raitt Street 2. Santa Ana Boulevard/Pacific Avenue 3. Santa Ana Boulevard/Shelton Street 4. Santa Ana Boulevard/Flower Street 5. Santa Ana Boulevard/Parton Street ® 7 f��