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4.8 Noise Grand Ave —South of 1-5 NIB Ramps 1 73.0 Grand Ave —North of 1-5 NB Ramos 1 797 SOURCE: PBS&J, 2010 (cc culafion data and results are provided in Appendix F). a. Distances are in feet from roadway centerline. The identified noise level at 50 feet from the roadway centerline is for reference purposes only. It does not reflect an actual building location or potential impact location. Existing Groundborne Vibration Levels The greatest regular source of ground -borne vibration in the Transit Zoning Code (SD 84A and SD 84B) area and in the immediate vicinity is roadway traffic, bus traffic, and rail traffic. Trucks and buses typically generate noticeable ground -borne vibration velocity levels at the edge of the road and typically produce a vibration level of 65 VdB at a distance of 50 feet from the roadway. Trains typically generate noticeable ground -borne vibration velocity levels at the edge of the right-of-way and typically produce a vibration level of 75 VdB at a distance of 50 feet from the tracks (HMMH 2O06). 4.8.2 Regulatory Framework Federal The U.S. Department of IIousing and Urban Development (HUD) has set a goal of 45 dBA Ldn as a desirable maximum interior standard for residential units developed under HUD funding. While HUD does not specify acceptable exterior noise levels, residential dwellings constructed under Title 24 of the California Code of Regulations typically provide 20 dBA of acoustical attenuation with the windows closed and 10 dBA with the windows open. Based on this assumption, the exterior Ld or CNEL should not exceed 65 dBA under normal conditions. State The California Department of Health Services (DHS) Office of Noise Control has previously studied the correlation of noise levels and their effects on various land uses (DHS no longer exists). The most current guidelines prepared by the State noise officer were issued in 1987. They are contained in the "General Plan Guidelines" issued by the Governor's Office of Planning and Research in 1998. Noise - compatible land use planning depends on the ability to locate noise -sensitive land uses in an acceptable environment. Exterior noise environments are "normally acceptable" for schools and residences if they are below 60 dBA Ldn (or CNEL) and "conditionally acceptable" below 70 dBA Ldn (or CNEL). A "conditionally acceptable" designation implies that new construction or development should be undertaken only after a detailed analysis of the noise reduction requirements and after necessary noise insulation features are incorporated into the design of the new land use. By comparison, a "normally acceptable" designation indicates that standard construction can occur without special noise reduction requirements. City of Santa Ana Transit Zoning Code (SD 84A and SD 848) EIR 4.8-11