2009-034 (2) - Final Supplemental Environmental Impact Report for Fairhaven/Lincoln

Home Browse Search

S. Environmental Analysis TRAFFIC AND CIRCULATION Intersections Two analysis methodologies were applied to assess traffic impacts: Intersection Capacity Utilization (ICU) methodology for signalized intersection performance and Highway Capacity Manual HMC Manual 2000 methodology for un ignali ed intersection performance. Intersection Capacity Utilization (ICU) Method - Signalized Intersections Level of service (LOS) qualitatively measures the operating conditions within a traffic system and hoer drivers and passengers perceive these conditions. The ICU Method determines an intersection LOS based on the percent of the allocated "green time" used by the approach volume. The intersection analysis was based on lost time as a percentage of total cycle length (green -Iight to red -Iight and back). Modeling ass rues a five percent clearance loss as a percentage of cycle length,1 ,700 vehicles per hour per lane for through Ianes, and 1,600 vehicles per hour per Ian for left-turn lanes. Table 5.3-2 provid es a summary of LOS definitions under the ICU methodology. LOS ranges from free flowing at A to overloaded conditions at F. LOS D is typically recognized as the minimum satisfactory service level in urban areas and is the level of service standard adopted by the City of Santa Ana. According to Congestion Management Program IVIP traffic impact analysis guidelines, LOS E is the minimum acceptable service level at CMP intersections. Highway Capacity Manual 11 2000 Method - Unsignalized Intersections Unsignalize I intersections were evaluated using the H M 2000 analysis methodology. LOS definitions for unignalized intersections using the HM 2000 method are described in Table . -. FairbavenlLincoln and Santa Clara Lincoln Intersection Modifications City of ` n a Page 5.3 SuPlement t to the Santa Ana Second Lain �ra `k Project EIR Resolution No. 2009 -034 Page 83 of 130 Table 5.3-2 Level of Service Criteria for Signalized Intersections 1C Level of Service Intersection Capacity L 0 Utilization Value C Level of Service Description lion 88 0.00-0.60 Free Flow /insignificant Delay: No approach phase is fuller utilized by traffic and no vehicle waits longer than one red indication Stable Operation/Minimal Delays: An occasional approach phase is fuIly B > 0.01— 0.70 utilized. Mang drivers begin to feel somewhat restricted within platoons of vehicles. 0 > 0.71— 0.80 Stable Operation /Acceptable Delays; Major approach phase fully utilized. Most drivers feel somewhat restricted. Approaching Unstable Tolerable Delays: Drivers may have to wait through D > 0.01 — 0.90 rnore than one red signal indication. Queues may develop, but dissipate r idl without excessive delays. Unstable Operations/Significant Delays: Volumes at or near capacity. E > 0.01 —1.00 Vehicles may wait through several signal cycles. Long queues from upstream from intersection. Forced Flow /Excessive Delays: Represents jammed conditions, Intersection F > 1.00 operates below capacity with low volumes. Queues may block upstream intersections and will "build" rather than stay constant. Source: DMJM Harris 2008 Highway Capacity Manual 11 2000 Method - Unsignalized Intersections Unsignalize I intersections were evaluated using the H M 2000 analysis methodology. LOS definitions for unignalized intersections using the HM 2000 method are described in Table . -. FairbavenlLincoln and Santa Clara Lincoln Intersection Modifications City of ` n a Page 5.3 SuPlement t to the Santa Ana Second Lain �ra `k Project EIR Resolution No. 2009 -034 Page 83 of 130