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Home My WebLink AboutCT 99-02; Poinsettia Properties Planning Area 7; Tentative Map (CT) (14)04/20x00 14:46 RECON -» 619 546 9472 NO. 374 002 INTERIOR NOISE ANALYSIS FOR POINESTT1A COVE CITY OF CARLSBAD, CALIFORNIA Prepared for FIELDSTONE COMPANY 5465 MOREHOUSE DRIVE, SUITE 250 SAN DIEGO, CALIFORNIA 92121 Prepared by CHARLES BULL ACOUSTICIAN RECON NUMBER 3132N April 18, 2000, 1927 Fifth Avenue, Suite 200 Son Diego, CA 92101 619/308-9333 fax 308-9334 This document printed on recycled paper 04/20/00 14:46 RECON -» 619 546 9472 NO. 374 D03 TABLE OF CONTENTS Summary of Findings 1 Applicable Standards 1 Acoustical Analysis 2 References Cited 4 TABLES I: Source Level Calculations for Roadway Traffic 3 2: Source Level Calculations for Rail Traffic 3 3: Summary of Interior Noise Levels 5 ATTACHMENT 1: Noise calculation results Roadway Traffic 2: Noise calculation results Rail Traffic 04/20x00 14:46 RECON -» 619 546 9472 NO. 374 084 Summary of Findings The proposed Poinsettia Cove project, located adjacent to Carlsbad Boulevard and Poinsettia Lane in the city of Carlsbad, will develop single-family residences on approximately 18.5 acres. The San Diego Northern Railroad (SDNRR) mainline runs adjacent to the project eastern boundary. As a result of an acoustic analysis prepared for the project, it was determined that noise levels for the units adjacent to the roadway could reach 72 decibels community noise equivalent level (CNEL) due to traffic on Carlsbad Boulevard and train activity. That analysis specified that interior noise levels at those units could exceed the City's 45 CNEL interior standard and that a subsequent analysis demonstrate conformance to the standard. This analysis confirms that the homes on the site are designed to insure that the CNEL in any habitable room due to exterior noise will not be greater than 45 decibels. The exterior noise level determined to be applicable for this analysis is 72 decibels CNEL. As such, the building shells need to provide a noise reduction of 27 decibels. As confirmed by this detailed analysis, the building shells will provide the required noise reduction. To achieve this reduction, it is necessary that the windows remain closed and that forced-air circulation or air conditioning be provided. In order to ensure that the required attenuation is provided, the windows and glass doors used in the project need to meet or exceed the sound transmission classes (STC) used in this analysis as follows. The proposed construction meets these parameters. Analyzed STC French door 26 Operable horizontal sliding windows 26 Fixed windows 28 Exterior doors 27 Applicable Standards The CNEL is a 24-hour A-weighted average sound level |dB(A) L^j from midnight to midnight obtained after the addition of 5 dB to sound levels occurring between 7:00 P.M. and 10:00 P.M. and of 10 dB to the sound levels occurring between 10:00 P.M. and 7:00 A.M. A-weighting is a frequency correction that often correlates well v/ilh the subjective response of humans to noise. The 5 dB and 10 dB penalties added to the evening and nighttime hours account for the added sensitivity of humans to noise during these time periods. 04/20/00 14:47 RECON -> 619 546 9472 NO. 374 P05 Acoustical Analysis The studied homes are located within the city of Carlsbad. An acoustical study prepared in 1999 (RECON 1999) indicated that the second floor of these homes could be exposed to exterior noise levels of 72 dB(A) CNEL. Therefore, a noise reduction of 27 decibels is required to achieve an interior noise level of 45 dB(A) CNEL. Window and door sizes and specifications for these floor plans were obtained from the building plans prepared by the Edinger Design Associates and dated February 2, 2000, The "habitable" rooms analyzed in this report include the living room/dining rooms, family rooms, master bedrooms, and other bedrooms. The analysis involved the computation of a composite transmission loss on an octave band basis. These octave band losses were then subtracted on an octave band basis from the source noise, adjusted for anticipated absorption, and converted to combined A-weighted interior CNEL. The results of these calculations are presented in Attachments 1 and 2 for traffic noise and train noise respectively. In order to calculate accurate transmission losses, it was first necessary to convert the 72 CNEL exterior noise levels to a spectral distribution. For roadway traffic, this distribution was obtained from the Handbook of Acoustical Measurements and Noise Control (Harris 1991). The spectral distribution for medium trucks was assumed to be the same as that for heavy trucks, The noise spectra for cars and heavy trucks were weighted to adjust for the traffic mix and added together. The resulting vehicle noise spectrum was adjusted to reflect A-weighting and was calibrated to reflect a 72 CNEL. Table 1 provides the resulting A-weighted vehicle noise spectrum for noise levels of 72 CNEL. For trains, the distribution was obtained from Assessment of Noise Environments Around Railroad Operations (Swing and Pies 1973). The spectral distribution for trains traveling on a smooth track. As with the road traffic, the resulting vehicle noise spectrum was adjusted to reflect A-weighting and was calibrated to reflect a 72 CNEL. Table 2 provides the resulting A-weighted vehicle noise spectrum for noise levels of 72 CNEL. 04/20/00 14:47 RECON -> 619 546 9472 NO.374 P06 TABLE 1 SOURCE LEVEL CALCULATIONS FOR ROADWAY TRAFFIC Source level A-weighting Resulting level 72 dB(A) level 125 75.8 -16.1 58.5 51.5 250 73.2 -8.6 63.3 56.3 500 74.8 -3.2 70.0 63.0 1000 71.6 0.0 70.6 63.6 2000 67.9 1.2 72.5 61.5 4000 63 1.0 63.2 56.2 Total 80.5 76.4 72.4 TABLE 2 SOURCE LEVEL CALCULATIONS FOR RAIL TRAFFIC Source level A-weighting Resulting level 72 <1B(A) level 125 73.0 -16.1 56.9 46.2 250 76.0 -8.6 67.4 56.8 500 82.0 -3.2 78.8 68.2 1000 78.0 0.0 78.0 67.4 2000 75.0 1.2 76.2 65.6 4000 69,0 1.0 70 59.4 Total 85.1 82.9 72.3 NOTE: Column headings are in hertz. Acoustical transmiSvSion loss data used in this analysis for the windows and doors were obtained from various sources. Acoustical transmission loss data was obtained from Sabine et al. (1975) for the exterior walls (test number W-50-71). The horizontal sliding windows data was obtained for Keller Industries (STC 26 - test number WEAL #TL88- 215), and data for the fixed windows was from International Window Corporation. A wood-framed pitched roof was obtained from Table A.43 and the french door from Table A.36 in Yaniv et al. (1986). All windows used were dual glazed. Absorption was calculated Tor each room based on the floor area of each room. For rooms where the exterior surface area is greater than the floor area of the room, the effect of the absorption was to decrease the noise reduction. Where the exterior surface was 04/20/00 14:48 RECON -» 619 546 9472 NO. 374 007 less than the area of the room, the absorption resulted in greater noise reduction. Table 3 presents the results of the acoustical calculations by room based on an exterior level of 72 CNEL. It should be noted that this is a worst-case analysis. The exterior noise level of 72 decibels was assumed for all faces of each building, when it actuality some walls will be perpendicular to the noise source. Furthermore, this worst-case exterior noise level was applied to all building configurations and for both first and second floor rooms. The noise analysis conducted by RECON in 1999 indicated that the majority of the homes will be exposed to noise levels less than 72 dBA CNEL. The fact that all rooms of the the proposed design meets the interior standard of 45 dBA CNEL with an exterior noise level of 72 decibels insures thai ihe composite transmission loss for each room is sufficient. The calculations performed here and summarized in Table 2 demonstrate that the building as designed meets the City's requirement for noise reduction with the condition that air conditioning or forced-air circulation with a summer switch be provided. This provision will allow the windows to remain closed. Windows and doors used in the project need to meet or exceed the analyzed STC values indicated above. References Cited Harris, Cyril M. 1991 Handbook of Acoustical Measurements and Noise Control. 3rd ed. McGraw- Hill, New York. RECON 1999 Noise Technical Report for Pacific Shores North, City of Carlsbad California, Sabine, Hale J., Myron B. Lacher, Daniel R. Flynn, and Thomas L. Quindry 1975 Acoustical and Thermal Performance of Exterior Residential Walls, Doors and Windows. NBS Building Science Series 77. U.S. Department of Commerce, National Bureau of Standards, Washington, D.C. Swing, Jack W. and Donald B. Pies 1973 Assessment of Noise Environments Around Railroad Operations. Wyle Laboratories Research Staff Report WCR 73-5. Wyle Laboratories El Segundo California. Yaniv, Simone L., Thomas W. Bartel, Larry A. Ronk, and Stephen F. Weber 1986 Soundproofing Buildings in the Vicinity of Airports: Field Manual. U.S. Department of Commerce, National Bureau of Standards, Gaithersburg, Maryland. 04/20/00 14:48 RECON -» 619 546 9472 NO.374 D08 TABLE 3 SUMMARY OF INTERIOR NOISE LEVELS Plan Al Al Al Al Al A2 A2 A2 A2 A2 A2 A3 A3 A3 A3 A3 A3 A4 A4 A4 A4 A4 A4 A4 Room Interior CNEL Units Overlooking Carlsbad Boulevard Living/dining room Family room/kitchen Master bedroom Bedroom 2 Bedroom 3 Living/dining/family Family room/kitchen Master bedroom Bedroom 2 Bedroom 3 Teen room Living/dining room Family room/kitchen Master bedroom Bedroom 2 Bedroom 3 Bedroom 4 Living/dining room Family room/kitchen Master bedroom Bedroom 2 Bedroom 3 Bedroom 4 Teen room 44 44 41 40 43 42 42 43 43 42 44 44 42 42 42 42 42 42 44 43 42 41 43 41 Interior CNEL Units Overlooking Train Tracks 44 43 40 40 42 42 42 42 42 41 42 44 42 41 41 41 40 41 44 41 40 40 42 39