P & D CONSULTANTS - 2002 - Laserfiche WebLink

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Grand Avenue Widening Project Environmental Impact Report Section 3.0 LOS Criteria for Road Segments For planning purposes, the City of Santa Ana has established the maximum road. capacity corresponding to different LOS designations based on road classifications, as shown in Table 3.5- 3. TABLE 3.5-3 MAXIMUM AVERAGE DAILY TRAFFIC FOR ARTERIAL ROADS Street Classification Lane Configuration LOS A LOS B LOS C LOS D LOS E LOS F Principal Arterial 8 Lanes Divided 45,000 52,500 60,000 67,500 75,000 > 75,000 Major Arterial 6 Lanes Divided 33,900 39,400 45,000 50,600 56,300 > 56,300 Primary Arterial 4 Lanes Divided 22,500 26,300 30,000 33,800 37,500 > 37,500 Secondary Arterial 4 Lanes Undivided 15,000 17,500 20,000 22,500 25,000 > 25,000 Commuter Street 1 2 Lanes Undivided_A 7,500 18,800 10,000 11,300 12,500 > 12,500 Source: City of Santa Ana, General Plan - Circulation Element, 1998. In this study, LOS for road segments was calculated by comparing traffic volumes to the LOS E capacity. This comparison yields a volume -to -capacity (V/C) ratio .from which the LOS is determined. LOS Criteria for Signalized Intersection Intersection operations were analyzed using the Intersection Capacity Utilization (ICU) method. ICU is a quantitative ratio which compares intersection volume with capacity. Based on the ICU, intersection performance is described using LOS designations as shown in Table 3.5-4. LOS A represents relatively light traffic conditions with minimum delay. LOS F represents heavy congestion with long queues and excessive delays. For this study, LOS D or better was considered to be the acceptable service level for peals hour conditions on the project segment of Grand Avenue. This is consistent with the City of Santa Ana's Circulation Element which establishes LOS D or better on major intersections in the City. The ICU analysis for this study used standard parameters currently followed by the City of Santa Ana. These standard parameters include default saturation flow rates (the maximum number of vehicles that can pass through a lane per hour of green time at a signalized intersection), and clearance interval (a percentage of the overall intersection capacity utilized by vehicles to clear the intersection during the amber or yellow signal), Default saturation flow rates of 1,600 vehicles per hour per lane (vphpl) for turn lanes and 1,700 vphpl for through lanes were used in the analysis. A value of 1,600 vphpl was also used to determine the ICU value for free right turn lanes; however, this ICU value was not included in the overall total for the intersection. Finally, a clearance interval of five percent was used for all intersections. F: IPROJ-ENMGrand eirWew Text - GrandWection 3 SplWSection 3.5.doc Page 3.5-8