HomeMy WebLinkAboutCT 97-16A; Kelly Ranch; Tentative Map (CT) (2)EXTERIOR NOISE ANALYSIS FOR
KELLY RANCH CORE AREA
CITY OF CARLSBAD
Report #97-126
June 9, 1997
Prepared For:
KELLY LAND COMPANY. INC.
2011 Palomar Airport Road
Suite 206
Carlsbad, CA 92009
(619)931-1190
Prepared By:
Vincent Mestre, P.E.
Henry Moon
MESTRE GREVE ASSOCIATES
280 Newport Center Drive
Suite 230
Newport Beach, CA 92660-7528
(714) 760-0891
SUMMARY OF MITIGATION REQUIREMENTS FOR
KELLY RANCH CORE AREA
EXTERIOR REQUIREMENTS
The City of Carlsbad General Plan specifies outdoor and indoor 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.
The projected unmitigated traffic noise exposure levels at the rear yards along Cannon Road will
range from 68.0 dB to 69.9 dB CNEL. Since the unmitigated noise levels at the rear yards exceed
the exterior noise standard, mitigation measures will be required.
NOISE BARRIER REQUIREMENTS TO MEET THE 60 CNEL STANDARD
A perimeter wall, 8.0 feet to 8.5 feet in height should be located along the top of slope between the
units facing Cannon Road and the roadway. Refer to Exhibit S1 for the location of the required
noise barriers. The required barriers will reduce the first floor exterior noise levels to a range of
57.2 to 59.1 dBA CNEL for the lots adjacent to Cannon Road. The different barrier height
locations are listed in Table S-l.
TABLE S-l
REQUIRED BARRIER HEIGHTS TO MEET THE 60 CNEL STANDARD
LOT NO. WALL HEIGHT (FT.)
Along Cannon Road
PadB 8.5
Pad A 8.0
PadAFF2 8.0
PadRV 8.5
NOISE BARRIER REQUIREMENTS TO MEET THE 65 CNEL STANDARD
A perimeter wall, 6.0 feet in height should be located along the top of slope between the units
facing Cannon Road and the roadway. Refer to Exhibit S2 for the location of the required noise
barriers. The required barriers will reduce the first floor exterior noise levels to a range of 61.3 to
64.1 dBA CNEL for the lots adjacent to Cannon Road. The different barrier height locations are
listed in Table S-2.
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TABLE S-2
REQUIRED BARRIER HEIGHTS TO MEET THE 65 CNEL STANDARD
LOT NO. WALL HEIGHT (FT.)
Along Cannon Road
PadB
Pad A
PadAFF2
PadRV
6.0
6.0
6.0
6.0
INTERIOR REQUIREMENTS
The proposed project must comply with the City's interior noise standard of 45 dB CNEL. To
comply with the interior noise standard, the proposed buildings must provide sufficient outdoor to
indoor noise attenuation to reduce the interior noise exposure down to acceptable levels. It is
assumed that the building face of the homes will be set back approximately 20 feet from the
property line. The projected unmitigated traffic noise exposure levels at the second floor building
faces will range from 67.1 dB CNEL to 68.7 dB CNEL. This means the structure must provide
from 22.1 to 23.7 dB of exterior to interior noise reduction. When the exterior to interior noise
reduction exceeds 20 dB, engineering calculations should be provided to ensure compliance with
the interior noise requirement The calculation of the noise reduction provided by the structures
can be accomplished when the final architectural plans are completed. An additional study will be
required when architectural drawings become available identifying mitigation requirements needed
to meet the interior noise standard.
MGA
NOISE ANALYSIS FOR KELLY RANCH CORE AREA
CITY OF CARLSBAD
1.0 INTRODUCTION
The purpose of this report is to determine compliance of Kelly Ranch Core Area with the City of
Carlsbad's exterior noise standards. The subject project is located along the south side of Cannon
Road west of El Camino Real in the City of Carlsbad. See Exhibit 1 for the location of the project
site. The project site is located approximately one mile north of McClellan Palomar Airport and
will not be impacted by the aircraft noise from this airport. The scope of this study includes the
noise generated by traffic on the adjacent arterials and the measures necessary to mitigate the noise
to within the exterior noise standard.
2.0 NOISE CRITERIA
The City of Carlsbad General Plan specifies outdoor and indoor 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 p.m. to 10 p.m.) is weighted by 5 dB, while noise which
occurs at nighttime (10 p.m. to 7 a.m.) is weighted by 10 dB. These time periods and weights
were selected to reflect peoples sensitivity to noise during late-night and early morning hours.
The "City of Carlsbad Noise Guidelines Manual," dated September, 1995, presents the "1995
Airport Noise Contours" and the "Airport Influence Area," for McClellan-Palomar Airport on
pages E-l and E-2, respectively. A residential development outside the airport's 60 CNEL noise
contour would not require any mitigation measures to comply with the City of Carlsbad noise
criteria. A residential development between the 60 and 65 CNEL contour would be conditionally
acceptable if the interior of the homes could be mitigated to below 45 CNEL interior noise
exposure. The city does not allow residential development inside the 65 CNEL noise contour.
3.0 METHODOLOGY
The highway noise levels projected in 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
program has been written which computes equivalent noise levels for each of the time periods used
in the calculation of CNEL. Weighting these noise levels and summing them results in the CNEL
for the traffic projections used. Noise contours are found by iterating over distance until the 60
dB, 65 dB, and 70 dB CNEL contours are found.
4.0 AIRCRAFT NOISE EXPOSURE
The Kelly Ranch Core Area is located approximately one mile north of McClellan-Palomar
Airport. It located outside the 60 CNEL noise contour for McClellan-Palomar Airport and will
therefore, not need any mitigation measures in regards to aircraft noise from McClellan-Palomar
Airport. Exhibit! shows the noise contours for McClellan-Palomar Airport as well as the location
of the project site.
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MESTRE GREVE ASSOCIATES
Exhibit 1
Project Site
5.0 TRAFFIC NOISE EXPOSURE
The project will be exposed to noise from traffic on Cannon Road. The future traffic volume
projections for the roadways in the project area are for the Carlsbad SANDAG Post 2010 Land
Use. These Post 2010 traffic volumes were obtained from Jim Murray, the traffic engineerfor the
City of Carlsbad, on May 1, 1997. The master tentative maps were received from Kelly Land
Company, Inc. on May 19, 1997. The traffic volumes and speeds utilized are presented in Table
1. The time and traffic distributions utilized for the analysis are from the document, "City of
Carlsbad Noise Guidelines Manual," September 1995 and are presented in Table 2. This data was
compiled by the City of Carlsbad and are based on traffic counts at 7 locations throughout the city.
The Carlsbad traffic mix is broken up into "non-truck route" traffic mix and "designated truck
route" traffic mix. The "non-truck route" traffic mix was used for the Cannon Road traffic noise
model. The traffic mix for the time of day was determined from the Orange County traffic mix
which is 78% day, 12% evening, and 10% night.
TABLE 1
POST 2010 TRAFFIC VOLUMES AND SPEEDS
TRAFFIC VOLUME SPEED
ROADWAY (ADT) (MPH)
Cannon Road 31,600 50
TABLE 2
TRAFFIC DISTRIBUTION PER TIME OF DAY
VEHICLE TYPE DAY EVENING NIGHT
Automobile
Medium Truck
Heavy Truck
76.35 %
1.43 %
0.22 %
11.75 %
0.22 %
0.03 %
9.79 %
0.18 %
0.03 %
Utilizing the traffic data presented above along with the FHWA Model, distances to the 60 dB, 65
dB and 70 dB CNEL contours were determined. The values, which are listed below in Table 3,
represent the distance from the centerline of the roadways to the contours. These projections do
not take into account any barriers, topography, or buildings that may reduce noise levels.
TABLE 3
DISTANCE TO NOISE CONTOURS FOR FUTURE CONDITIONS
ROADWAY DISTANCE TO CNEL CONTOUR (ft)
SEGMENT 70 dB 65 dB 60 dB
Cannon Road
Soft Site Conditions 74 160 344
Hard Site Conditions 120 379 1,197
MCA
The units along Cannon Road will be exposed to the highest noise levels. These lots adjacent to
Cannon Road will be located approximately 70 to 95 feet from the centerline of Cannon Road. At
these distances, the rear yard areas will be exposed to unmitigated noise levels of 69.9 to 68.0
dBA CNEL and the building face of the homes that were assumed to be set back an additional 20
feet from the property line will be exposed to unmitigated noise levels from 68.7 to 67 1 dBA
CNEL.
6.0 EXTERIOR NOISE MITIGATION
Mitigation through the design and construction of a noise barrier (wall, berm, or combination
wall/berm) is the most efficient method of reducing traffic noise levels. 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.
According to the site plan, the lots adjacent to Cannon Road are set back approximately 70 feet
from the roadway centerline of Cannon Road. All of the residential pad elevations along Cannon
Road are higher than the roadway elevations. Therefore, the barriers should be placed at the edge
of the property line. In general, the barriers should be located at the top of slope whether it is at
the property line or at the top of the berm near the roadway edge.
6.1 NOISE BARRIER REQUIREMENTS TO MEET THE 60 CNEL STANDARD
A perimeter wall, 8.0 feet to 8.5 feet in height should be located along the top of slope between the
units facing Cannon Road and the roadway. Refer to Exhibit 3 for the location of the required
noise barriers. The required barriers will reduce the first floor exterior noise levels to a range of
57.2 to 59.1 dBA CNEL for the lots adjacent to Cannon Road. The different barrier height
locations are listed in Table 4.
TABLE 4
REQUIRED BARRIER HEIGHTS TO MEET THE 60 CNEL STANDARD
LOT NO. WALL HEIGHT (FT.)
Along Cannon Road
PadB 8.5
Pad A 8.0
Pad AFF2 8.0
PadRV 8.5
6.2 NOISE BARRIER REQUIREMENTS TO MEET THE 65 CNEL STANDARD
A perimeter wall, 6.0 feet in height should be located along the top of slope between the units
facing Cannon Road and the roadway. Refer to Exhibit 3 for the location of the required noise
barriers. The required barriers will reduce the first floor exterior noise levels to a range of 61.3 to
64.1 dBA CNEL for the lots adjacent to Cannon Road. The different barrier height locations are
listed in Table 5.
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TABLE 5
REQUIRED BARRIER HEIGHtS TO MEET THE 65 CNEL STANDARD
LOT NO. WALL HEIGHT (FT.)
Along Cannon Road
PadB
Pad A
PadAFF2
PadRV
6.0
6.0
6.0
6.0
6.3 NOISE BARRIER SURFACE DENSITY REQUIREMENTS
The aforementioned 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 a solid wall, an earthen benn, or a
combination of the two. They may be constructed of wood studs with stucco exterior, 3/8 inch
plate glass, 5/8 inch plexiglass, any masonry material, or a combination of these materials.
7.0 INTERIOR NOISE MITIGATION
The proposed project must comply with the City's interior noise standard of 45 dB CNEL. To
comply with the interior noise standard, the proposed buildings must provide sufficient outdoor to
indoor noise attenuation to reduce the interior noise exposure down to acceptable levels. It is
assumed that the building face of the homes will be set back approximately 20 feet from the
property line. The projected unmitigated traffic noise exposure levels at the second floor building
faces will range from 67.1 dB CNEL to 68.7 dB CNEL. This means the structure must provide
from 22.1 to 23.7 dB of exterior to interior noise reduction. When the exterior to interior noise
reduction exceeds 20 dB, engineering calculations should be provided to ensure compliance with
the interior noise requirement The calculation of the noise reduction provided by the structures
can be accomplished when the final architectural plans are completed. An additional study will be
required when architectural drawings become available identifying mitigation requirements needed
to meet the interior noise standard.
MGA
APPENDIX
CROSS SECTION DATA FOR CANNON ROAD
Lot
PadB
1
2
3'
Pad A
4
5
Pad AFF2
6
7
8
Pad RV
9
10
11
Pad AFF 1
12
13
Road
Elevation
53
56.8
59.9
61.2
59.4
58
53
51
27
25
25
26.6
26.6
CL
To Wall
70
70
75
85
95
90
95
85
70
70
85
225
220
ED. to
Wall
65
65
71
81
92
86
92
81
65
65
81
224
219
Base Of
Wall
65
65
65
70
70
75
75
75
35
35
35
55
55
CLto
Observer
75
75
80
90
100
95
100
90
75
75
90
230
225
E.D.to
Observer
70
70
76
86
97
91
97
86
70
70
86
229
224
Pad
Elevation
65
65
65
70
70
75
75
75
35
35
35
55
55
Observer
Height
6
6
6
6
6
6
6
6
6
6
6
6
6
Note: The lot numbers shown above are randomly assigned numbers to each
Pad Area and do not correspond to any actual lot numbers.
MGA