2011-022 - Addendum to the FInal Environmental Impact Report No. 2004-02

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Project Study Methodology analysis zone (TAZ) system which encompasses the five (5) counties in the Southern California region. The primary focus of the modeling area is Orange County. The OCTAM 3.3 model uses the latest adopted demographic forecasts, commonly referred to as Orange County Projections, adopted in 2006 (OCP- 2006). The OCP -2006 demographic forecasts include data in 5 year increments through 2035 and are the official Orange County forecasts. The growth in housing, population, and employment included in the OCP -2006 demographic projections is consistent with the anticipated growth that is expected in conjunction with the cities' General Plan land use and circulation elements. The latest OCTAM 3.3 model data were used as the basis for producing the refined 2035 future intersection turning movement volumes based on the algorithm obtained from the report Highway Traffic Data for Urbanized Area Project Planning and Design (National Cooperative Highway Research Program Report 255, Transportation Research Board, 1952, pp. 105 -109), commonly referred to as NCHRP -255. Minor manual adjustments have been conducted for traffic flow conservation and reasonableness checks. Appendix C includes the initial refined 2035 turning movement volumes for each intersection from the OCTAM model based on the NCHRP -255 methodology. Significant impact Criteria The City of Santa Ana, City of Costa Mesa, and City of Irvine have similar but slightly different significant impact criteria to identify intersections that can be categorized as either satisfactory or deficient, so that appropriate mitigation measures can be made for non - satisfactory intersections to bring them to satisfactory operating conditions. The City of Santa Ana's project impact analysis criteria indicate: • A significant project impact occurs when the ICU value increases by greater than .01 and achieves unacceptable level of service ( "E" or "F" ). Since no relevant unsignalized intersections are included in the study, the criteria for unsignalized intersections are not listed herein. The significant impact criteria provided above are based on the City's General Plan. In addition, projects must also comply with the Orange County Congestion Management Plan (CMP) criteria. The CMP specifies that a project cannot be allowed to reduce level of service or increase flow by more than 3% at a location that is forecast to experience Level of Service E or F, generally. This criterion is generally less stringent than the City's criteria, so any project that meets the City General Plan criteria will also normally meet the County CMP criteria. KOA CORPORATION Updated Main and MacArthur Development Project PLANNING & ENGINEERING 7 Traffic Impact Study in City of Santa Ana