HomeMy WebLinkAboutCT 90-31; AVIARA P8 28; Planning CommissionAIRPORT
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AVIARA PLANNING AREA 28
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City of Carlsbad
c CT~ 90-31/' II:
PUD 91-4
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PRELIM:INARY EXTERIOR NOISE ANALYSIS
FOR PLANNING AREA 28
CITY OF CARLSBAD
Report # 90-267
December 6, 1990
Prepared For.
Hillman Properties West, Inc.
2011 Palomar Airport Road
Suite 206
Carlsbad, CA 92009
Prepared By:
Vincent Mestre, P.E.
:Milce Holritz
MESTRE GREVE ASSOCIATES
280 Newport Center Drive
Suite 230
NeWport Beach, CA 92660-7528
(714)760-0891
SUMMARY
e Mestre Greve ASsociates
Report # 90-267
Page 1
MINIMUM REQUIREMENTS TO MEET
CITY OF CARLSBAD STANDARDS
Report #90-267
December 6, 1990
EXTt:RIOR NOISE LEVELS
The residences in tht;: project must comply with the City's 60 CNEL exterior noise standard.
Without mitigation, exterior observers would experience a worst case traffic noise level of 69.1
CNEL at Lot 40. A number of outdoor living areas in the project will require mitigation to comply
with'the 60 CNEL exterior noise standard. Those exterior areas which require mitigation are listed
below in Table S 1. The data used in the noise barrier analysis are shown in the Appendix.
Table Sl
REQUIRED REAR YARD
NOISE BARRIER HEIGHTS AND LOCATIONS
TO MEET THE 60 CNEL EXTERIOR STANDARD
LOT
38
39 through 42
43 through 48
49 through 53
I BARRIER HEIGHT (FT)*
7.5
8.5
8.0
7.5
* -Denotes height above top of slope
With the noise barriers listed in Table S 1, the noise leyels at all exterior living areas in the project
will. be reduced to below 60 CNEL. These noise barriers shall be located. at top of slope.
The noise barriers must have a surface density of at least 3.5 pounds per square foot, and have no
openings or cracks. The noise barriers may be a wall, berm, or a combination of the t'oiVO. The wall
may be constructed of 1/4 inch plate glass, 5/8 inch plexiglass, any masonry material, or a
combination of these materials.
INTERIOR NOISE LEVELS
The project must comply with the City of Carlsbad indoor noise standard. With the exterior noise
mitigation listed above, buildings in the project will be exposed to a maximum noise level of 59.5
CNEL at the building on Lot 49. With standard construction practices in California, residential
buildings achieve outdoor to indoor noise reductions of at least 20 dB assuming windows are
closed. Therefore, the project will meet the 45 CNEL interior noise stand~d without building
upgrades.
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MECHANICAL VENTILATION REQUIREMENTS
Mestre Greve Associates
Report # 90-267
Page 2
The project consists exclusively of single story buildings. Therefore, with the exterior noise
mitigation listed. in Table 51, all buildings in the project will be exposed to noise levels ofless than
60 CNEL Mechanical ventilation wiII not be required for Planning Area 28.
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1.0 INTRODUCTION
.e
PRELIMINARY EXTERIOR
NOISE ANALYSIS FOR
AVIARA PLANNING AREA 28
CITY 0 F CARLSB AD
Mestre Greve Associates
Repon # 90-267
Page 3
The purpose of this report is to show compliance of Planning Area 28 with the noise related
'Conditions of Approval' placed on the project by the City of Carlsbad. The project calls for the
development of single Story homes. This repon incorporates the 60 CNEL exterior noise standard
adopted by the City of Carlsbad. The project is located in the City of Carlsbad, east of Interstate 5,
as shown in Exhibit 1. The project site will be impacted by traffic noise from Interstate 5. The
project is not impacted uy railroad or aircraft noise. This srudy detennines the need for any
mitigation measures to meet the 60 CNEL exterior noise standard, and addresses the 45 CNEL
interior noise standard required by the City of Carlsbad.
2.0 NOISE CRITERIA
The predominant rating scale now used in California for land-use compatibility assessment is the
Community Noise Equivalent Level (CNEL). CNE.. is a 24-hour time weighted annual average
noise level based on the A-weighted decibel. A-weighting is a frequency correction that correlates
overall sound pressure levels with the frequency response of the human ear. Time weighting refers
to the fact that noise that occurs during certain sensitive time periods is penalized for occuning at
these times. The evening time period (7 PM to 10 PM) penalizes noises by 5 dB, while nighttime
(10 PM to 7 AM) noises are penalized by 10 dB. These time periods and penalties were selected. to
reflect peoples sensitivity to noise as a function of activity.
The City of Carlsbad requires that outdoor living areas not exceed a noise level of 60 CNEL for a
six-foot-tall observer located five feet mthm the property line. In addition, interior noise. levels may
not exceed. 45 CNEL.
The site plan for the projeCt (Exhibit 2) was prepared by P & D Technologies (''Tentative Map for
Aviara Planning Area 28; October 19, 1990").
3.0 METHODOLOGY
The noise levels projected in the next section of this report were computed using the Highway
Noise Model published by the Federal Highway Administration ("F1ffi' A Highway Traffic Noise
Prediction Model", FRWA-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
~sed 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 reached.
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OCEANSIDE VISTA
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Exhibit 1 -Vicinity Map
MESTRE GREVE ASSOCIATES
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• Mestre Greve ASsociates
Report # 90-267
Page 4
Mitigation through the design and construction of a noise barrier (wall, benn, or combination
wa.J.llQenn) is the most common way of alleviating traffic noise impacts. The effect of a noise
barrier is critically dependent upon the geometry between the noise source, the barrier, and the
observer. A noise barrier effect occurs when the "line of sight" between the noise source and the
observer is penetrated by the barrier. The greater the penetration, the greater the noise reduction.
The FHW A model was also used here in computerized format to dete~e thp rCflulred barrier
heights. ur~
4.0 ROADWAY NOISE ~=r=.===-=---
The future traffic volwne for Interstate 5 was obtained from thCarlsbad Noise E~estre
Greve Associates, July 7, 1990. The future average daily traffic between
Poinsettia Lane and La Costa is 215,600. A vehicle speed of 60 miles per hour was utilized. Traffic
distribution for each of the time periods used in the CNEL calculation is presented in Table 1. These
traffic distribution estimates are based. upon traffic surveys, and are considered typical for freeways
in Southern California.
Table 1
TRAFFIC DISTRIBUTION. PER TIME OF DAY
IN PERCENT OF ADT
VEHICLE TYPE
Automobile
Medium Truck
Heavy Truck
DAY
65.83
2.92
2.10
l
EVENrn'G NIGHT
17.98
0.20
0.23
9.49
0.50
0.75
Using the assumptions presented above, the future noise levels were computed. The results are
reported here in Table 2 in terms of distances to the 60,6.5, and 70 CNEL contours. These
represent the distances from the centerline of the roadway to the contour value shown. Note that the
values given in Table 2 do not take into account the effects of intervening topography that may
affect the roadway noise exposure. Topographic effects are included. in subsequent analyses to
determine the actual noise exposure on the project site. In addition, these projections do not include
any future vehicle noise reduction assumptions to take into account the effects of legislation
requiring quieter vehicles in the furore .
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Table 2
DISTANCE TO NOISE CONTOURS
FOR FUTURE TRAFFIC CONDITIONS
.: Mestre Greve Associates
Report # 90-267
Page 5
FREEWAY SEGNtENT DISTANCE TO CNEL CONTOUR (FI)
-70--65--60-
Interstate 5
Poinsettia to La Costa 2,107 6,664 21,074
The results in Table 3 and the site plan (Exhibit 2) indicate that a number of exterior living areas in
the project will be exposed to traffic noise levels in excess of 60 CNEL. Exterior observers facing
Interstate 5 will experience a worst case traffic noise level of 69.1 CNEL at Loe 40.
5.0 EXTERIOR NOISE MITIGATION
For the exterior living areas which are exposed to noise levels greater than 60 CNEL, some form of
noise mitigation is required. An effective method of reducing the traffic noise levels to acceptable
levels is with a noise bamer. Representative cross-sections along the roadway (see Appendix for
analysis data) were analyzed. utilizing the FHW A Model to determine the necessary noise barrier
locations and heights. The results of the analysis indicate that in order to meet the 60 CNEL exterior
noise standard, noise bamers are required. for a number of exterior living areas facing Interstate 5.
Required noise barrier locations and heights to meet the 60 CNEL exterior noise standard are listed
in Table 3, and shown in Exhibit 3. The noise barriers shall be located. at top of slope as shown in
Exhibit 3.
Table 3
REQUIRED REAR YARD
NOISE BARRIER HEIGHTS AND LOCATIONS
TO MEET THE 60 CNEL EXTERIOR STANDARD
LOT
38
39 through 42
43 through 48
49 through 53
* -Denotes height above top of slope
BARRIER HEIGHT (FI)*
7.5
. 8.5
8.0
7.5
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• • Mestre Greve Associates
Report # 90-267
Page 6
The noise barriers may be a walL berm. or combination wal1/berm. 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 masonry material, or a combination of these materials.
6.0 INTERIOR NOISE MITIGATION
The project must comply with the City of Carlsbad indoor noise standard. The project consists
exclusively of single Story buildings. With the exterior noise mitigation described in section 5.0,
building faces in the project will be exposed to a maximum noise level of 59.5 CNEL at the
building on Lot 49, therefore requiring at least 14.5 dB outdoor to indoor noise reduction to meet
the interior standard. With standard construction practices in California, residential buildings
achieve outdoor to indoor noise reductions of at least 20 dB assuming windows are closed.
Therefore, all buildings in the project will meet the 45 CNEL interior noise standard without
building up grades.
7.0 MECHANICAL VENTILATION REQUIREMENTS
Since the noise attenuation of a building falls to abOut 15 dB with windows open, any buildings
exposed to noise levels greater than 60 CNEL would meet the 45 CNEL interior noise standard
only with windows closed. The project consists exclusively of single story buildings. Therefore,
with the exterior noise mitigation described in section 5.0, all building faces in the project will be
exposed to noise levels of less than 60 CNEL. Mechanical ventilation win noe be reguired for
Planning Area 28.
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lot
38
39
40
41
43
45
47
49
51
53
55
57
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APPENDIX
Mestre Greve Associntes
Report # 90-267
Page 7
DATA USED TO DESIGN NOISE BARRIERS
ALONG INTERSTATE S
Road Distance BaSe Of Dist. To Pad Observer
Elevation To Wall Wall Observer Elevation Height
21.5 1500 75 1555 75 5
21.5 1590 75 15S5 75 5 , 21.5 1500 74 1505 74 5
21.5 1720 70.5 1725 70.5 5
21.5 1880 53.9 1885 53.9 5
21.5 2020 41.3 2025 41.3 5
21.5 2140 38.5 2145 38.5 5
21.5 2260 35.7 2255 36.7 5
21.5 2390 40 2395 40 5
21.5 2S2O 52.9 2525 52.9 5
21.5 / 2750 54.1 2755 54.1 5
21.5 2770 54.1 2950 59.3 5
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AflPORT
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