EXHIBIT 4-2_55A_BRISTOL WIDENING TECHNICAL STUDIES

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result in even greater community benefits). The Federal -Aid Highway Program Manual., Volume 7, Chapter 7, Section 3 (FHPM 7.7.3) has established design noise•ievels for different activity categories. Residences, schools, and recreation areas are in activity Category 8 which specifies an exterior design noise level of 67 dBA (Leq). Most commercial areas are in activity Category C with a corresponding design noise level of 72 dBA (Leq). The design noise levels for all activity categories appear in Table 4 -2 and are to be applied to: - those undeveloped lands for which development is planned, designed and programmed on the date of public knowledge of the highway or other federally funded construction project; - those activities and land uses in existence on the date of public knowledge of the project; and - those areas which have regular human use and in which a lowered noise level would be of benefit. The FHW A noise abatement criteria establish an exterior noise level for residential uses of 67 Leq. An interior level of 52 Leq applies where: (1) no exterior activity area is identified or (2) the exterior activities are either remote from the highway or shielded in some manner so that they will not be significantly affected by the noise (but the interior activities will). The criteria apply to private yard areas and assume that typical wood frame homes provide a 10 dB (outdoor to indoor) noise reduc- tion with windows open and a 20 dB reduction with windows closed. Under federal noise standards, traffic noise impacts occur when the predicted noise levels approach or exceed the noise abatement criteria, or when the predicted traffic noise levels substantial- ly exceed the existing noise levels. City Standards: The City of Santa Ana General. Plan Noise Ele- ment, includes a series of goals, implementation policies, and implementation programs related to land use compatibility with noise. Table 4 -3 lists the "desirable maximum" and "acceptable maximum" noise levels for various land uses, as noted in the General Plan. As shown in Table 4--3, the desirable maximum noise level for residential uses ranges from 55 to 65 CNEL depending upon density, and the maximum acceptable noise level ranges from 65 to 70 CNEL. Commercial and office uses have a desirable maximum noise level of 65 CNEL and a maximum acceptable noise level. of 75 CNEL. Industrial land uses have the same maximum acceptable noise level as commercial uses (75 CNEL) but a higher desirable maximum noise level (70 CNEL). In addition to the noise compatibility guidelines specified in the Noise Element, the City has adopted a Noise Control Ordinance (August 21, 1978) which specifies maximum noise levels which can be generated at the property line of residences, churches, 4 -4