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12.0 STATE OF CALIFORNIA (CALTRANS) METHODOLOGY <br />In conformance with the current Caltrans Guide for the Preparation of Traffic Impact Studies, <br />existing and projected AM and PM peak hour operating conditions at the two (2) state-controlled <br />study intersections within the study area have been evaluated using the Highway Capacity Manual <br />61h Edition operations method of analysis. These state-controlled locations include the following <br />intersections: <br />3. SR- 55 Ramps at Fourth Street 4. SR -55 NB Ramps at Fourth St/Irvine Blvd <br />Caltrans "endeavors to maintain a target LOS at the transition between LOS "C" and LOS "D" on <br />State highway facilities'; it does not require that LOS "D" (shall) be maintained. However, Caltrans <br />acknowledges that this may not always be feasible and recommends that the lead agency consult <br />with Caltrans to determine the appropriate target LOS. For this analysis, LOS D is the target level of <br />service standard and will be utilized to assess the project impacts at the state-controlled study <br />intersections. <br />12.1 Highway Capacity Manual (HCM) Method of Analysis (Signalized Intersections) <br />AM and PM peak hour operating conditions for the key study intersections were evaluated using the <br />methodology outlined in Chapter 19 of the Highway Capacity Manual 6 (HCM 6) for signalized <br />intersections. Based on the HCM operations method of analysis, level of service for signalized <br />intersections and approaches is defined in terms of control delay, which is a measure of the increase <br />in travel time due to traffic signal control, driver discomfort, and fuel consumption. Control delay <br />includes the delay associated with vehicles slowing in advance of an intersection, the time spent <br />stopped on an intersection approach, the time spent as vehicles move up in the queue, and the time <br />needed for vehicles to accelerate to their desired speed. LOS criteria for traffic signals are stated in <br />terms of the control delay in seconds per vehicle. The LOS thresholds established for the automobile <br />mode at a signalized intersection are shown in Table 12-1. <br />75B-112 <br />