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City of Santa Ana Main Place Mall Transformation Project <br />Traffic Impact Study <br />3.3 Intersection Analysis Methodology <br />The cities of Santa Ana and Orange use the Intersection Capacity Utilization (ICU) capacity methodology <br />for signalized intersections and the Highway Capacity Manual (HCM) delay methodology for unsignalized <br />intersections. For intersections under the jurisdiction of Caltrans, the HCM methodology for signalized <br />intersections is used. <br />The ICU methodology provides a comparison of the theoretical hourly vehicular capacity of an intersection <br />to the number of vehicles actually passing through that intersection during a given hour. The results of <br />the evaluation are reported in terms of Level of Service (LOS), which is represented by letter grades A <br />(excellent, free -flow conditions) through F (severely congested conditions). <br />Using the HCM methodology, Level of Service is based on the average vehicle delay, expressed in seconds <br />of delay per vehicle, for all movements at signalized and all -way stop -controlled intersections. For one- <br />way or two-way stop -controlled intersections, Level of Service is based on the average delay for the <br />approach with the highest delay. As with the ICU methodology, the average seconds of delay per vehicle <br />translates into a corresponding Level of Service, ranging from LOS A, representing uncongested, free - <br />flowing conditions; to LOS F, representing congested, over -capacity conditions. <br />Table 3 identifies each Level of Service category for both methodologies, and the corresponding <br />intersection capacity utilization or vehicle delay: <br />Table 3: Level of Service Ranges <br />LOS <br />ICU <br />Methodology <br />(WC Ratio) <br />HCM Methodology <br />(Seconds of delay per vehicle) <br />Signalized <br />Unsignalized <br />A <br /><0.60 <br /><10 <br /><10 <br />B <br />0.61-0.70 <br />>10-20 <br />>10-15 <br />C <br />0.71-0.80 <br />>20-35 <br />>15-25 <br />D <br />0.81-0.90 <br />>35-55 <br />>25-35 <br />E <br />0.91-1.00 <br />>55-80 <br />>35-50 <br />F <br />> 1.00 <br />> 80 <br />> 50 <br />LOS = Level of Service; ICU = Intersection Capacity Utilization; HCM = <br />Highway Capacity Manual; V/C = volume -to -capacity <br />3.3.1 Roadway Segment Analysis <br />Roadway segments are evaluated by comparing the daily traffic volume on a roadway segment to the <br />daily capacity of that segment. Daily capacity is based on the roadway configuration, including number of <br />travel lanes and the presence or lack of a center roadway divider. Table 4 and Table 5 show the roadway <br />capacity assumptions for the cities of Santa Ana and Orange, respectively. <br />Kimley>»Horn Page 112 <br />