The URL can be used to link to this page

Home My WebLink AboutCT 97-15; Lohf Property; Tentative Map (CT) (2)NOISE ANALYSIS FOR LOHF PROPERTY CITY OF CARLSBAD 1 r&RLSBAD - Report #98-91 May 11, 1998 Prepared For: WESTERN PACIFIC HOUSING 2385 Camino Vida Roble, Suite 107 Carlsbad, CA 92009 Prepared By: Fred Greve RE. Keith Utsler MESTRE GREVE ASSOCIATES 280 Newport Center Drive Suite 230 Newport Beach, CA 92660-7528 (714) 760-0891 \tre Greve Associates Noise Analysis for Lohf Property Pagel SUMMARY MITIGATION REQUIREMENTS LOHF PROPERTY CITY OF CARLSBAD EXTERIOR REQUIREMENTS The outdoor living areas in the project must comply with the City of Carlsbad's 60 CNEL outdoor noise standard. The nearest outdoor living areas adjacent to Poinsettia Lane and El Camino Real will experience future traffic noise levels in excess of 60 CNEL, and therefore, mitigation measures in terms of noise barriers are required. Noise barriers of 5.5 feet high are required for the outdoor living areas of Lots 68. 34 through 37. 40 through 52. and 74 along Poinsettia Lane, and noise barriers of 5.0 feet high are required for Lots 69 through 71 along El Camino Real. The required noise barriers should be relative to the top of slope. The top of slope refers to the higher elevation between the pad elevation and the roadway elevation. The required noise barrier heights and locations are listed in Table SI and shown Exhibit SI. Table SI REQUIRED NOISE BARRIER HEIGHTS AND LOCATIONS HEIGHT OF WALL LOT (FEET) ALONG POINSETTIA LANE 68 5.5 34 through 37 5.5 40 through 52 5.5 74 5.5 ALONG EL CAMINO REAL 69 through 71 5.0 Note: Noise barrier ar.&relative to the top of slop. The top of slope refers to the higher elevation between the pad and the roadway elevations. With the required noise barriers, all outdoor living areas in the project are projected to meet the City's 60 CNEL outdoor noise standard. The noise barriers are required to have a surface density of at least 3.5 pounds per square foot, and have no openings or cracks. They may be constructed of wood studs with stucco exterior, 1/4 inch plate glass, 5/8 inch plexiglass, any masonary material, or a combination of these material. fstre Greve Associates Noise Analysis for Lohf Property Page 2 INTERIOR REQUIREMENTS The proposed project must comply with the City's interior noise standard of 45 dB CNEL. The homes typically have a set back distance of 20 feet from the edges of the lots. Based on this distance, the nearest homes will be exposed to a worst case traffic noise level of approximately 64.9 CNEL, resulting in a maximum outdoor to indoor noise attenuation of approximately 19.9 dBA in order to meet the indoor noise standard of 45 CNEL. The analysis was based on soft site conditions. Detailed engineering calculations are only necessary for homes requiring an outdoor to indoor noise reduction of greater than 20 dB. Since the buildings in the project will experience traffic noise levels less than 65 CNEL. the buildings in the project will meet the 45 CNEL indoor noise standard, assuming with conventional building construction which usually achieve at least a 20 dB noise reduction. With windows open, the outdoor to indoor noise reduction of a building falls to about 12 dB. Therefore, for those homes experiencing a noise level greater than 57 CNEL, window must remain closed to meet the indoor noise standard. A number of homes along the roadways will need to keep windows closed in order to comply with the 45 CNEL indoor noise standard. In order to have windows closed, adequate ventilation must be provided per Uniform Building Code for the units in the project. This can be achieved with mechanical ventilation to provide fresh air. The system must supply two air changes per hour to each habitable room including 20% fresh make-up air obtained directly from the outside. The fresh air inlet duct shall be of sound attenuating construction and shall consist of a minimum of ten feet of straight or curved duct, or six feet plus one sharp 90 degree bend. The system must meet the requirements of the UBC, and this should be coordinated with the mechanical engineer of the project. Mechanical ventilation will be required for all units of the buildings on Lots 34 through 37.40 through 52. 59 through 61. and 68 through 73 (see Exhibit Greve Associates Noise Analysis for Lohf Property Page3 NOISE ASSESSMENT FOR THE LOHF PROPERTY CITY OF CARLSBAD 1.0 INTRODUCTION The purpose of this report is to demonstrate compliance of the Lohf Property with the City of Carlsbad noise standards. The project calls for the development of single-family residences along Poinsettia Lane and El Camino Real. Refer to Exhibit 1 for the location of the project site. The project site will be exposed to future traffic noise from Poinsettia Lane and El Camino Real. The project site will not be exposed to any significant aircraft and train noise. This study determines the necessity for any exterior and interior mitigation measures to provide adequate protection for the residential units in the project. 2.0 NOISE CRITERIA The predominant rating scale now in use in California for land use compatibility assessment is the Community Noise Equivalent Level (CNEL). CNEL is a 24 hour time weighted annual average noise level based on the A-weighted decibel. The Noise Element of the City of Carlsbad General Plan specifies outdoor noise limits for various land-uses. The standard states that for residential land use, the exterior Community Noise Equivalent Level (CNEL) shall not exceed 60 dB. CNEL is a 24 hour time weighted average noise level. Noise that occurs during the evening period (7 PM to 10 PM) is weighted by 5 dB, while noises occurring in the nighttime (10 PM to 7 AM) are weighted by 10 dB. These time periods and weights were selected to reflect sensitivity to noise as a function of time of occurrence. The indoor noise standard is 45 CNEL. 3.0 ROADWAY NOISE The noise levels projected in the next section of this report were computed using the Highway Noise Model published by the Federal Highway Administration ("FHWA Highway Traffic Noise Prediction Model", FHWA-RD-77-108, December 1978). The FHWA Model uses traffic volume, vehicle mix, vehicle speed, and roadway geometry to compute the "equivalent noise level". A computer code has been written which computes equivalent noise levels for each of the time periods used in CNEL. Weighting these noise levels and summing them results in the CNEL for the traffic projections used. CNEL contours are found by iterating over many distances until the distance to 60, 65, and 70 CNEL contours are found. The future average dailly traffic (ADT) volumes for Poinsettia Lane and El Camino Real were obtained from the City of Carlsbad Transportation Department, September 29, 1997. The traffic distribution estimates are based upon traffic surveys, and are considered typical for arterials in Southern California. The traffic volumes and speeds utilized are presented in Table 1. The time and traffic distributions utilized are presented in Table 2. COooo: ?stre Greve Associates Noise Analysis for Lohf Property Page 4 Table 1 FUTURE TRAFFIC VOLUMES AND SPEEDS ROADWAY SEGMENT TRAFFIC VOLUME SPEED (ADT) (MPH) PoinsettiaLane 42,200 50 El Camino Real 14,100 50 Table 2 TRAFFIC DISTRIBUTION PER TIME OF DAY IN PERCENT OF ADT VEHICLE TYPE DAY EVENING NIGHT Automobile Medium Truck Heavy Truck 75.51 1.56 0.64 12.57 0.09 0.02 9.34 0.19 0.08 Utilizing the traffic data presented above and the FHWA Model, distances to the 60 dB, 65 dB and 70 dB CNEL contours were determined. The distances from the centerline of the roadway to these contours are presented below in Table 3. The noise contours are also presented graphically in Exhibit 2. These projections do not take into account any barriers, topography, or buildings that may reduce noise levels. In addition, equivalent lane distances to the wall and observer are calculated per the FHWA Manual and are included in the Appendix. Table 3 DISTANCE TO NOISE CONTOURS FOR FUTURE CONDITIONS DISTANCE TO CNEL CONTOUR (FEET) SEGMENT 70 dB 65 dB 60 dB El Camino Real 92 199 428 PoinsettiaLane 44 96 177 festre Greve Associates Noise Analysis for Lohf Property Page5 4.0 EXTERIOR NOISE MITIGATION Mitigation through the design and construction of a noise barrier (wall, berm, or combination wallA>erm) is the most common way of alleviating traffic noise impacts. The effect of a noise barrier is critically dependent on the geometry between the noise source and the receiver. A noise barrier effect occurs when the "line of sight" between the source and receiver is broken by the barrier. The greater the distance the sound must travel around the barrier to reach the receiver, the greater the noise reduction of the barrier. The FHWA model was also used here in a computerized format to determine barrier heights. The outdoor living areas in the project must comply with the City of Carlsbad's 60 CNEL outdoor noise standard. The nearest outdoor living areas adjacent to Poinsettia Lane and El Camino Real will experience future traffic noise levels in excess of 60 CNEL, and therefore, mitigation measures in terms of noise barriers are required. Noise barriers of 5.5 feet high are required for the outdoor living areas of Lots 68. 34 through 37. 40 through 52. and 74 along Poinsettia Lane, and noise barriers of 5.0 feet high are required for Lots 69 through 71 along El Camino Real. The required noise barriers should be relative to the top of slope. The top of slope refers to the higher elevation between the pad elevation and the roadway elevation. The required noise barrier heights and locations are listed in Table 4 and shown Exhibit 3. Table 4 REQUIRED NOISE BARRIER HEIGHTS AND LOCATIONS HEIGHT OF WALL LOT (FEET) ALONG POINSETTIA LANE 68 5.5 34 through 37 5.5 40 through 52 5.5 74 5.5 ALONG EL CAMINO REAL 69 through 71 5.0 Note: Noise barrier are relative to the top of slop. The top of slope refers to the higher elevation between the pad and the roadway elevations. With the required noise barriers, all outdoor living areas in the project are projected to meet the City's 60 CNEL outdoor noise standard. The noise barriers are required to have a surface density of at least 3.5 pounds per square foot, and have no openings or cracks. They may be constructed of wood studs with stucco exterior, 1/4 inch plate glass, 5/8 inch plexiglass, any masonary material, or a combination of these material. NdV I 3^ .- 050 '-^2 NcV fstre Greve Associates Noise Analysis for Lohf Property Page 6 5.0 INTERIOR NOISE LEVELS The residential buildings must comply with the City's interior noise standard of 45 dB CNEL. The homes typically have a set back distance of 20 feet from the edges of the lots. Based on this distance, the nearest homes are projected to be exposed to a worst case noise level of approximately 64.9 CNEL. This results in a maximum outdoor to indoor noise attenuation of approximately 19.9 dBA in order to meet the indoor noise standard of 45 CNEL. The analysis was based on soft site conditions. Detailed engineering calculations are only necessary for homes requiring an outdoor to indoor noise reduction of greater than 20 dB. Since the buildings in the project will experience traffic noise levels less than 65 CNEL. the buildings in the project will meet the 45 CNEL indoor noise standard, assuming with conventional building construction which usually achieve at least a 20 dB noise reduction. With windows open, the outdoor to indoor noise reduction of a building falls to about 12 dB. Therefore, for those homes experiencing a noise level greater than 57 CNEL, window must remain closed to meet the indoor noise standard. A number of homes along the roadways will need to keep windows closed in order to comply with the 45 CNEL indoor noise standard. In order to have windows closed, adequate ventilation must be provided per Uniform Building Code for the units in the project. This can be achieved with mechanical ventilation to provide fresh air. The system must supply two air changes per hour to each habitable room including 20% fresh make-up air obtained directly from the outside. The fresh air inlet duct shall be of sound attenuating construction and shall consist of a minimum of ten feet of straight or curved duct, or six feet plus one sharp 90 degree bend. The system must meet the requirements of the UBC, and this should be coordinated with the mechanical engineer of the project. Mechanical ventilation will be required for all units of the buildings on Lots 34 through 37.40 through 52. 59 through 61. and 68 through 73 (see Exhibit 4) •>SS^.>';j-r<-:-. . ./ ;:'.\ Vi Q ;•'*te ;--x •,-•'-•/ } \ltt- metTestre Greve Associates Noise Analysis for Lohf Property Page? APPENDIX DATA USED TO DESIGN NOISE BARRIERS (along) POISETTIA Lot 34 40 42 46 48 52 Road Elavation 268.0 263.0 262.0 257.0 258.0 264.0 Distance to Wall 64 60 62 77 100 105 Base of Wall 268.0 263.0 262.0 257.0 262.1 271.9 Distance to Observer 87 80 71 82 105 110 Pad Elevation 260.1 256.2 254.1 252.0 262.1 271.9 Distance to Building 102 95 86 97 120 125 (along) EL CAMINO REAL Road Distance Base of Distance to Pad Distance to Lot Elavation to Wall Wall Observer Elevation Building 69 77 252.4* 248.3* 300 410 252.4 248.3 305 415 252.4 248.3 102 430 worst case scenario