Appendix A Traffic Analysis Report

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TRAFFIC IMPACT ANALYSIS FAIRVIEW STREET IMPROVEMENTS FROM 9T" STREET TO 16T" STREET AND /\ JUNE 2018 BRIDGE REPLACEMENT PROJECT J" SANTA ANA, CALIFORNIA hour at any one intersection. The especially high -delay values shown in Table A should not be considered representative of actual delay times due to typical driver behavior. For example, high delays calculated for outbound movements at the intersection of Fairview Street and 9th Street that reach into the hundreds of seconds per vehicle would not be tolerated by drivers making outbound lefts. It is reasonable to expect drivers to make more feasible route choices such as making right turns out to make subsequent U-turns at downstream intersections, as they are available. As shown in Table B, the segments of Fairview Street (including the bridge) that provide only four lanes of travel currently experience daily traffic volumes greater than their respective design capacities, meaning these roadway segments currently experience unsatisfactory LOS F. FUTURE CONDITIONS LSA prepared future traffic forecasts (provided in Appendix C) for 2021 and 2040 No Build and Build conditions using the long-range traffic modeling tool, the Orange County Transportation Analysis Model (OCTAM). OCTAM is a travel demand model derived from the Southern California Association of Governments (SCAG) Regional Model that provides more specific land use and network information for Orange County. The 2021 traffic forecasts represent the anticipated conditions at the anticipated project completion year, whereas 2040 traffic forecasts represent long-range design year traffic conditions. The intersection and roadway segment traffic volumes for 2040 No Build and Build conditions were developed using the OCTAM base year (2012) and future year (2040) model unconstrained networks. Raw traffic model data from OCTAM base and future year model runs were post - processed using National Cooperative Highway Research Program (NCHRP) 255 methodologies to develop peak -hour turning movement volumes at each study area intersection and roadway segment. The following describes the methodology used to post -process model volumes to develop peak hour intersection volumes for 2040 No Build and Build conditions: The difference between the modeled 2012 and 2040 peak period directional arterial traffic volumes (for each intersection approach and departure) was identified from loaded network plots. This difference defines growth in traffic over the 28-year period. The incremental growth in peak period approach and departure volumes between 2012 and 2040 was factored to develop the incremental change in peak -hour volumes. OCTAM uses a 3-hour a.m. peak period and a 4-hour p.m. peak period. SCAG has established that the a.m. peak hour accounts for 38 percent of the peak period and the p.m. peak hour is 28 percent of the peak period. Therefore, the incremental changes in peak period volumes were multiplied by the appropriate factors to develop incremental changes in peak -hour volumes. The incremental growth in approach and departure volumes between 2012 and 2040 for each movement and peak hour was factored to reflect the forecast growth between the year of the existing traffic data (2017) and 2040. For this purpose, LSA assumed linear growth between the 2012 base condition and the forecast 2040 condition. As the increment between Existing and 2040 is 23 years of the 28-year time span, a factor of 0.82 (i.e., 23/28) was used. PAWKE1702\Traffic\doc\Traffic Analysis Report rev - Caltrans Comments.docx u06/07/18» 9