HomeMy WebLinkAboutCT 94-04; Poinsettia Shores PA 1; Tentative Map (CT) (7)INDOOR AND OUTDOOR NOISE ANALYSIS FOR
POINSETTIA SHORES (PLANNING AREA A-1)
CITY OF CARLSBAD
Report #94-95
June 14, 1994
Prepared For:
KAIZA POINSETTIA CORPORATION
7220 Avenida Encinas
Suite 200
Carlsbad, CA 92009
Prepared By:
Fred Greve, P.E.
Tanya Nguyen
MESTRE GREVE ASSOCIATES
280 Newport Center Drive
Suite 230
Newport Beach, CA 92660-7528
(714)760-0891
oMestestre Greve Associates
Planning Area A-l
Pagel
SUMMARY OF MITIGATION MEASURES REQUIRED FOR
POINSETTIA SHORES (PLANNING AREA A-l)
CITY OF CARLSBAD
EXTERIOR NOISE LEVELS
The rear yard areas in Planning Area A-l must comply with the City of Carlsbad outdoor noise
standard of 60 CNEL. A number of rear yard areas in the project will be exposed to traffic noise
from Avenida Encinas as well as the Interstate 5 Freeway (1-5). The analysis indicates that these
rear yard areas will be exposed to a worst case traffic noise level of approximately 64.7 CNEL.
Therefore, in order to meet the 60 CNEL noise standard, the rear yards along the roadways will
need noise mitigation measures in terms of sound walls. (It should be noted that the noise
analysis includes the noise reduction due to the existing slope which locates between the project
site and the Interstate 5 Freeway).
In order to meet the 60 CNEL noise standard, double noise barriers will be needed for the rear
yard areas of Lots 170 through 180 adjacent to Avenida Encinas. (Lot 206 will be an open
space). The noise barriers adjacent to Avenida Encinas 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 second noise barrier will be required along the 1-5 Freeway. This second noise barrier will
need to be 6 feet in height. The required noise barrier heights and locations are shown below in
TableS-land Exhibits.
Table S-l
REQUIRED NOISE BARRIER HEIGHT AND LOCATION
LOT# Barrier Height (feet) *Barrier Height (feet) *Top-of-Wall
relative to top of slope along 1-5 Freeway (1-5 Freeway)
ALONG AVENIDA ENCINAS/INTERSTATE 5
(below 60 CNEL for outdoor areas)
180 ^
176 through 179
171 through 175
170
6.0
6.0
5.5
6.0
6.0
6.0
-
"~
114
115
. -
•*
NOTE: The top of slope refers to the higher elevation between the pad elevation and
the roadway elevation.
* Double barrier needed along the 1-5 Freeway. The location of this barrier is
shown in Exhibit S. The top-of-wall should descend in a linear manner.
With the required noise barriers, all outdoor living areas in the project will 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
MESTRE GREVE ASSOCIATES
Exhibit 2
Noise Barrier Height and Location
Mestestre Greve Associates
Planning Area A-l
Page 2
wood studs with stucco exterior, 1/4 inch plate glass, 5/8 inch plexiglass, any masonry material,
or a combination of these material.
INTERIOR NOISE LEVELS
The buildings along AvenidaEncinas will experience traffic noise levels in excess of 60 dBA
CNEL. The analysis indicates that the buildings in the project will experience a worst case traffic
noise level of approximately 64.5 dBA. This results in a maximum outdoor to indoor noise
building attenuation of approximately 19.5 dBA in order to meet the City of Carlsbad's 45 CNEL
interior noise standard. Detailed engineering calculations which demonstrate the noise reduction
levels are necessary for residential building attenuation requirements of greater than 20 dB.
The noise analysis was based on the architectural plans titled"Poinsettia Shores Planning Areas
A-l and A-l, The Village of Deauville", prepared by H Architects Lonmer»Case, April 27,1994.
The construction specifications for this project which were utilized in estimating the outdoor to
indoor noise reduction are presented below.
Roof is attic space construction and incorporates concrete tiles on the exterior with
gypsum drywall on the interior surface. This roof includes fiber glass insulation in
stud cavity and is sloped.
Exterior walls are wood stud construction with stucco siding and minimum 1/2 inch
gypsum drywall on the interior. All exterior walls include fiberglass insulation in
stud cavity.
Standard glass window has minimum single-strength plate glass.
Standard sliding glass door has minimum 3116 inch glazed glass.
French entry door has solid core 1-314 inch thick wood and weather-stripping.
The results of the analysis indicated that with the standard constructions described above, the
buildings in the project will achieve; outdoor to indoor noise attenuations of greater than the required
maximum noise reduction (19.5 dBA). Therefore, no building upgrades are required for any of the
buildings in the project *•
A number of units along the roadway will require windows closed to achieve the. interior noise
standard of 45 CNEL. In order to assume windows can remain closed to achieve this required
attenuation, adequate ventilation with windows closed must be provided per Uniform Building
Code. 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. Air conditioning is an adequate substitute for mechanical ventilation as long as it meets
the UBC (Section 1205 (c)) requirements. Mechanical ventilation will be required for buildings on
Lots 170 through 180 along AvenidaEncinas.
c oMestre Greve Associates
Planning Area A-l
Page3
INDOOR AND OUTDOOR NOISE ANALYSIS FOR
POINSETTIA SHORES (PLANNING AREA A-1)
CITY OF CARLSBAD
1.0 INTRODUCTION
The purpose of this report is to demonstrate compliance of Planning Area A-l with the noise
related'Conditions of Approval' placed on the project by the City of Carlsbad. The project calls
for the development of single-family residential units. The report addresses the future exterior
and interior noise levels at the project site. The project site is located adjacent to AvenidaEncinas
and the Interstate 5 Freeway as shown in Exhibit 1. The project will be exposed primarily to
traffic noise from these roadways. This study determines the need 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. A-weighting is a frequency correction that
correlates overall sound pressure levels with the frequency of the human ear. Time weighting
refers to the fact that noise that occurs during certain sensitive time periods is penalized for
occurring 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 noise standards require that outdoor living areas not exceed a noise level of
60 CNEL. The City's 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 ("FHWAHighway 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.
Mitigation through the design and construction of a noise barrier (wall, berm, or combination
wall/berm)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 penetrated by the
barrier. The greater the penetration the greater the noise reduction. The FHWA model was also
used here in computerized format to determine barrier heights.
The future traffic volume for Avenida Encinas was taken from the traffic study "Traffic Impact
MESTRE GREVE ASSOCIATES
CITY OF OCEANSIDE
CITY OF VISTA
CITY OF
SAN MARCOS
Exhibit 1
Vicinity Map
oMestre Greve Associates
Planning Area A-1
Page 4
Analysis for Kaiza Poinsettia Development, Zone 9" prepared by P & D Technologies, April
1991. The traffic was projected for Year 2010. A vehicle speed of 40 miles per hour (mph) was
utilized. The traffic distribution estimates are based upon traffic surveys, and are considered
typical for arterials in Southern California. The traffic volume and speed utilized are presented in
Table 1. The time and traffic distributions utilized are presented in Table 2 and is considered a
worst case assumption for Avenida Encinas. The truck mix used with the FHWA Model for the I-
5 Freeway were 3.26 percent medium trucks and 3.73 percent heavy trucks obtained from the
Caltrans Highway Traffic Manual (1988).
Table 1
FUTURE TRAFFIC VOLUME AND SPEED
ROADWAY TRAFFIC VOLUME SPEED
Avenida Encinas 6,900 40
1-5 Freeway 215,600 60
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
Using the assumptions presented above, the future noise levels were computed. The results are
reported here in Table 3 are in terms of distances to the 60, 65, 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 3 do not take into account the effect of intervening topography that may
affect the roadway noise exposure. In addition, the wall and observer are calculated per the
FHWA Manual and are included in the Appendix.
oMesitre Greve Associates
Planning Area A-1
PageS
Table 3
DISTANCE TO NOISE CONTOURS
FOR FUTURE TRAFFIC CONDITIONS
ROADWAY SEGMENT
DISTANCE TO CNEL CONTOUR (FT)
-70- -65- -60-
AVENIDAENCINAS 19 42 90
The results in Table 3 indicate that the rear yard areas along AvenidaEncinas and the 1-5 Freeway
will be exposed to traffic noise levels in excess of 60 CNEL. The nearest rear yard will
experience a worst case combined traffic noise level of approximately 64.7 CNEL. The nearest
building along Avenida Encinas will experience a worst case traffic noise level of approximately
64.5 CNEL. These noise levels include the shielding due to the natural existing slope between
the project site and the freeway.
4.0 EXTERIOR NOISE MITIGATION
Mitigation through the design and construction of a noise barrier (wall, berm, or combination
wall/berm) 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 a 6 foot 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.
A number of rear yard areas in the project will be exposed to traffic noise from AvenidaEncinas
as well as the Interstate 5 Freeway (1-5). The analysis indicates that these rear yard areas will be
exposed to a worst case traffic noise level of approximately 64.7 CNEL. Therefore, in order to
meet the 60 CNEL noise standard, the rear yards along the roadways will need noise mitigation
measures in terms of sound walls. (It should be noted that the noise analysis includes the noise
reduction due to the existing slope which locates between the project site and the Interstate 5
Freeway). i
In order to meet the 60 CNEL noise standard, double noise barriers will be needed.for the rear
yard areas of Lots 170 through 180 adjacent to Avenida Encinas. The noise barriers adjacent to
Avenida Encinas 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 second noise barrier will be
required along the 1-5 Freeway. This second noise barrier will need to be approximately 6 feet in
height. The required noise barrier heights and locations are shown below in Table 4 and Exhibit
2.
o
Mestre Greve Associates
Planning Area A-1
Page 6
Table 4
REQUIRED NOISE BARRIER HEIGHT AND LOCATION
LOT# Barrier Height (feet) *Barrier Height (feet) *Top-of-WaU
relative to top of slope along 1-5 Freeway (1-5 Freeway)
ALONG AVENIDA ENCINAS/INTERSTATE 5
(below 60 CNELfor outdoor areas)
180 6.0 6.0 114
176 through 179 6.0 6.0 115
171 through 175 5.5
170 6.0
NOTE: The top of slope refers to the higher elevation between the pad elevation and
the roadway elevation.
* Double barrier needed along the 1-5 Freeway. The location of this barrier is
shown in Exhibit 2. The top-of-wall should descend in a linear manner.
The above required noise barriers will cause the combined noise levels for all outdoor living
areas to fall below 60 CNEL. 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 material.
7.0 INTERIOR NOISE LEVELS
The buildings along Avenida Encinas will be experience a worst case traffic noise level of
approximately 64.5 CNEL. Therefore, these buildings will require a worst case outdoor to
indoor noise attenuation of 19.5 dBA in order to meet the City of Carlsbad 45 CNEL interior
noise standard. Detailed engineering calculations which demonstrate the noise reduction levels
are necessary fpX residential building attenuation requirements of greater than 20 dB.
To comply with the interior noise standard the buildings must provide sufficient outdoor to
indoor building attenuation to reduce the noise levels down to acceptable levels. The outdoor to
indoor noise reduction characteristics of a building are determined by combining the transmission
loss of each of the building elements which make up the building. Each unique building element
has a characteristic transmission loss. For residential units the critical building elements are the
roof, walls, windows, doors, attic configuration and insulation. The total noise reduction
achieved is dependent on the transmission loss of each element and the area of that element in
relation to the total surface area of the room. Room absorption is the final factor used in
determining the total noise reduction.
For interior noise analysis, the most direct way of computing the total noise reduction is through
the use of the methodology published by the Federal Highway Administration ("Insulation of
Buildings Against Highway Noise," FHWA TS 77-202). This methodology consists of
applying a single number rating concept weighted for highway noise. The FHWA methodology
Exhibit 2
Noise Barrier Height and LocationMESTRE GREVE ASSOCIATES
Mestre Greve Associates
Planning Area A-l
Page 7
incorporates the Exterior Wall Noise Rating scale (EWNR). This is similar to the more
traditional Sound Transmission Class (STC) rating except that EWNR is specifically weighted
for transportation noise sources. The FHWA has published EWNR data for the noise reduction
characteristics of various building elements and construction techniques. This noise attenuation
data is based upon empirically derived data on construction materials in practice today.
The noise analysis were based on the architectural plans titled "Poinsettia Shores Planning Areas
A-l and A-l, The Village of Deauville", prepared by H. Architects Lprimer»Case, April 27,1994
The construction specifications for this project which were utilized in estimating the outdoor to
indoor noise reduction are presented below.
Roof is attic space construction and incorporates concrete tiles on the exterior with
gypsum drywallon the interior surface. This roof includes fiber glass insulation in
stud cavity and is sloped.
Exterior walls are wood stud construction with stucco siding and minimum 112 inch
gypsum drywall on the interior. All exterior walls include fiberglass insulation in
stud cavity.
Standard glass window has minimum single-strength plate glass.
Standard sliding glass door has minimum 3116 inch glazed glass.
Entry door has solid core 1-314 inch thick wood and weather-stripping.
To assess compliance of the project with the interior noise standard, a worst case room for each
building plan was selected for analysis. In general, the worst case room is the second story
corner room with the greatest amount of window area. Corner rooms have more exterior surface
area for noise infiltration. Rooms with large window areas have the least noise reduction,
because windows typically are the weakest part of the structure. Table 5 displays some sample
of the building element areas and EWNR values (as given by the FHWA) used to compute the
total noise reduction. The total outdoor to indoor noise reductions without upgrades are given in
Table 5.
O o
Mestre Greve Associates
Planning Area A-1
PageS
Table 5
DATA USED TO COMPUTE THE EXTERIOR TO INTERIOR NOISE
REDUCTION WITHOUT UPGRADES
BUILDING AREA EWNR
ELEMENT (SQ. FT.) (DB)
without upgrades
Plan B - Second Floor Corner Master Bedroom
Roof 240 36
Wall 188 40
Window (sliding) 30 22
Window (fixed) 30 26
Total Noise Reduction (dB): 25.5
Worst Case Required Noise Reduction (dB): 19.5
Plan B - Second Floor Corner Master Bedroom (Optional deck)
Roof 240 36
Wall 188 40
Window (sliding) 15 22
Window (fixed) 30 26
Door (entry) 19 35
Total Noise Reduction (dB): 26.8
Worst Case Required Noise Reduction (dB): 19.5
Plan C - Second Floor Corner Master Bedroom (Balcony)
Roof 322 36
Wall 128 40
Window (sliding) 75 22
Window (entry) 19 35
Total Noise Reduction (dB): 23.8
Worst Case Required Noise Reduction (dB): 19.5
The results show that with the standard construction plans the total outdoor to indoor noise
reduction with windows closed for the worst case rooms in each plan is greater than the
maximum required attenuation (19.5 dB). Thus, the buildings in the project will meet the interior
noise standard of 45 CNEL with no building upgrades as currently designed, assuming
windows are closed.
With windows open, the outdoor to indoor noise reduction of a building falls to 12 dBA.
Therefore windows must be closable for units experiencing an outdoor noise level greater than
57 CNEL. In order to assume windows can remain closed to achieve this required attenuation,
adequate ventilation with windows closed must be provided per Uniform Building Code. 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. Air
Mestre Greve Associates
Planning Area A-1
Page 9
conditioning is an adequate substitute for mechanical ventilation as long as it meets the UBC
(Section 1205 (c)) requirements. Mechanical ventilation will be required for buildings on Lots
170 through 180 along Avenida Encinas.
Mestre Greve Associates
Planning Area A-1
Page 10
APPENDIX
DATA USED TO DESIGN NOISE BARRIERS
Lot
Road
Elevation
Centerline
Distance To
To Wall
Centerline
Base Of
Wall
Distance To
Observer
Pad
Elevation
Observer
Height
Wall
Height
ALONG AVENIDAENCINAS
180
178
176
174
172
170
206
180
178
176
90
82
80
77
73.8
70
84
84
82
80
47
47
46
42
42
45
135
130
150
270
90
82
80
77
73.8
70
INTERSTATE
107
108
110
110
65
58
55
52
47
52
5 FREEWAY
280
265
275
440
82
80.7
79.1
76.3
73.8
70.9
84
82
80.7
79.1
6
6
6
6
6
6
6
6
6
6
6.0
6.0
6.0
5.5
5.5
6.0
6.0
6.0
6.0
6.0