HomeMy WebLinkAboutNOISE_ELEMENT_STUDY_1973 I IlhVll IIII III IIVI VIIIII IIIII nVll IIII III IIII
NOISE ELEMENT STUDY_1913
Wyle Laboratories Research Staff
Report WCR 73-3
NOISE ELEMENT STUDY OF HIGHWAY TRAFFIC NOISE IN
NEWPORT BEACH. CALIFORNIA
Prepared By:
Fancher M. Murray
Wyle Laboratories
128 Maryland Street
El Segundo, California 90245
Prepared For:
CITY OF NEWPORT BEACH
Newport Beach, California
May 1973
TABLE OF CONTENTS
Page
SUMMARY . . . . . . . . . . . . . . I
ENABLING LEGISLATION . . . . . . . . . . . 2
SCOPE OF SERVICES . . . . . . . . . . . . 2
INTRODUCTION . . . . . . . . . . . . . 4
MEASUREMENT AND ANALYSIS OF HOURLY NOISE DATA - - 5
TYPICAL A-WEIGHTED LEVELS . . . . . . . . . . 10
MEASURED COMMUNITY NOISE EXPOSURE LEVEL . . . . . 11
SEASONAL VARIATION OF COMMUNITY NOISE EXPOSURE LEVEL 11
AMBIENT NOISE IN QUIET AREAS . . . . . . . . . 13
PROPAGATION OF HIGHWAY NOISE INTO THE COMMUNITY 14
HELICOPTER NOISE . . . . . . . . . . . . 25
Police Helicopter . . . . . . . . . . . . 25
Military Helicopter . . . . . . . . . . . 27
METHODS AND EFFECTS OF NOISE REDUCTION . . . . . . 27
1 . Barriers . . . . . . . . . . . . . 27
2. Vehicular Control . o . . . . . . . . 28
3. Zoning Changes . . . . . . . . . . . 29
REFERENCES . . . . . . . . . . . . . . 30
APPENDIX A . . . .. . . . . . . . . . . A-1
SUMMARY
This program was sponsored by the City of Newport Beach in compliance with the ston-
dards and guidelines contained in Senate Bill 691 (California Government Code 65302).
This code required that any new general plan of incorporated cities include a noise ele-
ment to consist of weighted noise level contours generated to show transportation noise
related to the various highways, freeways, rapid transit systems and airport ground
facilities. The data is to be weighted to show total energy; that is, a scale must be
used which includes duration of sound as well as amplitude.
This report provides the required noise contours due to highway vehicles for the major
streets in the City of Newport Beach. The contour s have been developed, in part,
with the support of measurements of the integrated "A" weighted sound levels taken at
curbside for a number of locations within the city. These are augmented by two different
types of measurements to determine level versus distance from the roadway. The largest
number of these measurements was made using an impulse noise generator capable of
simulating the spectrum of vehicle noise and radiating very high sound pressure levels so
that measurements could be made at reasonable distances. This impulse generator was
supplemented by a measurement of the integrated "A" weighted traffic noise using five-
minute samples. The principal results of the study are illustrated in Figure I by the
estimated noise contours for highway vehicles only.
Some helicopter noise measurements have been made for both police and military fly-
avers, but routes flown by these vehicles are sufficiently variable that predictions of
noise produced in certain locations is not possible.
ENABLING LEGISLATION
This report is to fulfill the acoustic requirements of Senate Bill 691 (California Govern-
ment Code 65302). The specific requirements of this bill are as follows:
(g) A noise element in quantitative, numerical terms, showing contours
of present and projected noise levels associated with all existing and proposed
major transportation elements. These include but are not I imited to the
following:
(1) Highways and freeways,
(2) Ground rapid transit systems,
(3) Ground facilities associated with all airports operating under a per-
mit from the State Department of Aeronautics.
These noise contours may be expressed in any standard acoustical scale
which includes both the magnitude of noise and frequency of its occurrence.
The recommended scale is sound level A, as.measured with A-weighting net-
work of a standard sound level meter, with corrections added for the time
duration per event and the total number of events per 24-hour period.
Noise contours shall be shown in minimum increments of five decibels
and shall be continued down to 65 dB(A). For regions involving hospitals,
rest homes, long-term medical or mental care, or outdoor recreational areas,
the contours shall be continued down to 45 dB(A).
Conclusions regarding appropriate site or route selection alternatives or
noise impact upon compatible land uses shall be included in the general plan.
The state, local, or private agency responsible for the construction or
maintenance of such transportation facilities shall provide'to the local agency
producing the general plan, a statement of the present and projected noise
levels of the facility, and any information which was used in the develop-
ment of such levels.
SCOPE OF SERVICES
The scope of services reported upon in this document include those of Phase I of Exhibit
"A" of the services agreement between Wyle Laboratories and the City of Newport
Beach dated November 26, 1972. Excerpts from this scope of services are repeated
here for reference:
PHASE I —MEASUREMENT AND ANALYSIS OF EXISTING NOISE LEVELS
This phase wil I involve four tasks. The first task shal I be to determine and map
noise contours in accordance with the standards and guidelines contained in
2
Senate Bill 691 (California Government Code 5302) for the following major
highways within the City of Newport Beach:
Pacific Coast Highway
MacArthur Boulevard
Jamboree Road
Newport Boulevard
Balboa Boulevard (between Balboa Pier and Pacific Coast Highway)
Irvine Avenue
Campus Drive (between MacArthur Boulevard and Irvine Avenue)
Bristol Street (between MacArthur Boulevard and Irvine Avenue)
Cliff Drive (between Irvine Avenue and Riverside Avenue)
Riverside Avenue (between Pacific Coast Highway and Cliff Drive)
The noise contours shall be derived from actual field measurements and analy-
tical studies by consultant of the selected highway network. Such character-
istics as daily and seasonal traffic flow, traffic mix, highway width and grades,
property grades, and adjacent land uses, together with traffic noise measure-
ments from selected highway field stations shall be reviewed and analyzed by
the Consultant and summarized into a series of noise profiles for various high-
way locations. From these noise profiles, the Consultant shall develop CNEL
(Community Noise Equivalent Level) contours for the total highway network
and all adjacent properties in conformance with the standards and guidelines
outlined in Senate Bill 691.
To assist the Consultant in calculating the various noise levels due to high-
way traffic, the City staff shall provide hourly traffic estimates for those
major highways listed above.
The second task under Phase I shall be to determine ambient noise levels in
vario—u-s—c—re—asM the community for different types of land uses. Community
noise field stations shall be established for such purposes and shall be so
located throughout the City as to measure a representative cross-section of
varying land use types and conditions within Newport Beach. The Consultant
shall confer with City staff as to the most appropriate location for the field
noise measurement stations.
The third task under Phase I shall be to make recommendations on how to
mininirtie—tWe—noise impact of existing highway traffic on various existing and
future land uses within the City of Newport Beach.
3
INTRODUCTION
The following report details the procedures and results of Wyle's efforts to accomplish
the objectives of the foregoing tasks. A map of Newport Beach has been generated to
show the hourly noise levels expected on the main highways of the City forming a rough
triangle around the Upper Newport Bay. Additional highways surround the lower Bay.
These levels have been specifically related to traffic count taken at the time the levels
were measured so that any given traffic data, at any time of day or year, may be trans-
lated into average noise levels covering any specific period covered by the traffic data.
Such conversions are detailed by both first and second order approximation techniques.
Correction factors are developed which wil I predict traffic noise conditions for streets
other than those studied when the proper criteria are applied to those streets. A term
has been used to define the acoustic average energy that a given location wil I exper-
ience when an average car or average truck passes that location once each hour. This
term has been shown to be relatively constant With reasonably small correction factors
for high speed, starting on a hill, long periods of idle in traffic jams, etc., to make it
even more closely approximate the average automobile at a given location. It is
called HNL* and is mathematically defined. Typical A-weighted noise levels at curb-
side have been tabulated. The daily Community Noise Exposure Level has been
measured by a sampling technique in five noisy locations and three quiet locations
within the City.
Seasonal variation of the Community Noise Exposure Level has not been established
because of lack of information on traffic varia tion, but methods are shown to accomplish
estimates of this variation.
Measurements of the decay of sound from the highways into the community have been
accomplished by pulse techniques. Information is given to demonstrate the validity of
these techniques as applied to the environs of Newport Beach.
4
MEASUREMENT AND ANALYSIS OF HOURLY NOISE DATA
Several different types of noise measurements were made during this program to establish
the noise levels in various areas of the City of Newport Beach. The first measurements
i ade consisted of one hour recordings of curbside noise levels as shown in Table I
n Table I
One Hour Noise Measurements
Time HNL
Location Date 24 Hour Decibels Remarks
Pacific Coast Highway 11/22/72 0800 74 2% Grade
and Marigold
Pacific Coast Highway 11/22/72 1030 76.8 Level
and Patolita
Pacific Coast Highway 11/17/72 1700 73.6 Level
and Bayside
Pacific Coast Highway 11/17/72 1110 76.2 3.5% Climb
and Dover
Pacific Coast Highway 11/17/72 1430 73.3 Level
and Lugonia
Balboa and 14th Street 12/1/72 1415 7o.4 Level
Balboa and 38th Street 11/22/72 0930 72.4 Near playground
Newport Boulevard 11/21/72 1200 79.8 Start on 4% grade
and Hospital Road Heavy traffic
Irvine and Francisco 11/20/72 1500 73.7 Level — in town
Jamboree and San 11/21/72 0830 73.2 100 Feet from traffic
Joaquin Hills
Dover and 16th Street 11/20/72 1330 69.6 Level — low speed
MacArthur and Port 12/1/72 1600 78.2 Top of grade —high
Westbourne speed
5
The Hourly Noise Levels (HNL) shown in Table I were derived by use of a computer to
determine the time in tenths of a second that the sound,pressure level was at any given
level. The levels were divided into one-decibel increments so that a count was made
10 times per second and the total was stored at a memory location representing the
particular level of interest. A total of fifty different levels were examined and totaled.
At the end of one hour, the total in each level was multiplied by the sound intensity
corresponding to that level and all these products were added together. This total
was then divided by the total number of counts (nominally 36,000) and the logarithm
of the resulting number was multipled by 10 to give the HNL. in algebraic form, the
HNL is given as:
50 SPL.
HNL = 10 Log E 10 7U I Ni N dB re 20 pN/m 2
Ii = 0
where
Ni = Number of counts at the i th level
SPL i = Sound pressure level of i th level
Thus, the HNL is a measure of the average noise level over one hour, which will
produce the same noise energy as the actual environment.
The HNL measurements of Table I form the basis for the map contours of Figure 1. Traffic
data for the highways under study does not give annual totals nor does it give daily or
seasonal variations for the total highway system. Therefore, the annual CNEL cannot be
derived from HNL measurements. A few daily CNELestimates were made from sampled
data. These.measurements, 'described in a later section,-were insufficient for defining
detailed CNEL contours for current conditions. Hourly estimates of traffic noise
(i.e., HNL), coupled with daily average.traffic counts, will enable computation of
CNEL data from Equation 2 in the appendix.
6
F\\
�TS
----------------
�ANL MEASNOM
0 OR REMOM
CitY af NewPort Beach Figure 1
Cont� or Highw molme Average
*DM MEMOM Fall.'19727
A-Wei
NoiseWl 7
Traffic counts were made during the recording of the noise levels of Table I in order
that the data might be used for determining further information for projection of future
noise levels. Table 11 is a tabulation of this traffic count.
Table 11
Traffic Count — Vehicles Per Hour During Measurements
HNL
(dB re 2
Location 20 ANIm Automobiles Trucks Motorcycles Buses
Pacific Coast Highway 74 1526 168 10 11
and Marigold
Pacific Coast Highway 76.8 2081 280 18 7
and Patolita
Pacific Coast Highway 73.6 3778 357 13 7
and Bayside
Pacific Coast Highway 76.3 1366 207 2 3
and Dover
Pacific Coast Highway 73.3 1814 242 3 9
and Lugonio
Balboa and 14th Street 70.4 890 105 14 14
Balboa and 38th Street 72.4 452 85 9 1
Newport Boulevard 79.8 2866 383 17 6
and Hospital Road
Irvine and Francisco 73.7 1328 169 16 7
Jamboree and 76.8 2653 247 17 30
Ford Road
Jamboree and San 73.2 2497 231 7 3
Joaquin Hills
Dover and 16th Street 69.2 1351 170 5 2
MacArthur and Port 78.2 2004 183 6 10
Westbourne
8
The total number of buses and motorcycles compared with the numbers of cars and trucks
is quite small even on the main arterial so that they do not constitute a significant
contribution to the total noise environment. Of the trucks counted, most of these are
of the pickup variety of less than 1-1/2 tons so that the noise attributable to an average
truck could not be placed at more than twice that attributable to an average car. Thus,
the data of Table 11 was used to obtain Table III wherein the number of cars is added to
two times the number of trucks.
Table III
Hourly Noise Level Per Event
(dB re 20 gNIm 2
HNL HNL*
Location dB dB
Pacific Coast Highway and Marigold 74 40.3
Pacific Coast Highway and Patolita 76.8 42.6
Pacific Coast Highway and Bayside 73.6 40.1
Pacific Coast Highway and Dover 76.2 41.7
Pacific Coast Highway and Lugonia 73.3 39.7
Balboa and 14th Street 70.4 40.0
Balboa and 38th Street 72.4 -2
Newport Boulevard and Hospital Road 79.8 42.2
Irvine and Francisco 73.7 41.5
Jamboree and Ford Road 76.8 40.8
Jamboree and Son Joaquin Hills 73.2 38.5
Dover and 16th Street 69.6 39.3
MacArthur and Port Westbourne 78.2 42.5
Average 40.7
IHNL* = HNL - 10 Log N
2 N = N c + 2 Nt, Nc = No. of Cars/Hour, Nt No. of Trucks/Hour
Data disregarded because of playground noise
The data of Table III is discussed in detail in the Appendix.
9
TYPICAL A-WEIGHTED LEVELS
The averaged levels described above do not give information about the peak levels
that may be experienced by a person standing on the curb as traffic passes. Statistical
analysis of the maximum levels may be used to determine those levels that are exceeded
any given percentage of the total time of measurement. Thus, the symbol L 10 may be
used to give the level that is exceeded 10 percent of the time. This level has been
found to be representative of the maximum levels that might be measured by a person
holding a sound level meter using the "A" weighted scale with fast meter response.
Table IV lists L 10 for each of the sites studied above.
Table IV
A-Weighted Levels Exceeded Ten Percent of the Time (L,O)
at Curbside in Decibels (re 20 IN/m2)
L 10
Location dB
Pacific Coast Highway and Marigold 84.0
Pacific Coast Highway and Patolito 86.0
Pacific Coast Highway and Bayside 83.0
Pacific Coast Highway and Dover 87.5
Pacific Coast Highway and Lugonia 82.5
Balboa and 14th Street 82.5
Balboa and 38th Street 83.5
Newport Boulevard and Hospital Road 89.0
Irvine and Francisco 82.5
Jamboree and Ford Road 88.0
Jamboree and San Joaquin Hills 92.5
Dover and 16th Street 78.5
MacArthur and Port Westbourne 85.5
10
MEASURED COMMUNITY NOISE EXPOSURE LEVEL
A brief program was conducted to show daily variation of the Hourly Noise Levels at
five locations within the City of Newport Beach. For this study, measurements were
made for approximately five minutes at each of several sites in the City at each of
several different times during one day. The data was recorded and analyzed in five
minute samples in the some manner as was used for the hour long sample studies in pre-
vious sections. Figure 2 illustrates the results of these measurements for the five
locations. it is immediately seen from this data that the daytime levels for the whole
day at every location monitored was between 70 and 80 decibels and each location is
reasonably stable within its own range. it may also be seen that areas where heavy
traffic does not decrease during the evening and nrighttime hours, the noise does not
drop as it does in the outlying and residential areas. Thus, while the hourly levels at
the comer of Pacific Coast Highway and Dover are never extremely high, the heavy
weighting applied to nighttime noise causes a high daily average or CNEL. Conditions
at Newport Boulevard and Hospital Road, high traffic, many trucks, and all night
operation, combine to produce a very high CNEL at curbside for that location.
SEASONAL VARIATION OF COMMUNITY NOISE EXPOSURE LEVEL
The seasonal variation of the CNEL cannot be evaluated without extensive measure-
ments of the seasonal variations of the traffic data. It is possible to make good esti-
mates of seasonal variations where estimates of traffic flow may be compared with the
traffic flow tabulated in Table 11 and by use of the data of Table V taken from Refer-
ence 1.
Table V
Residual Noise Level With Changes in Traffic Flow
Change in
Residual Noise Level
dB(A)
Increase density of heavy trucks by factor of 4 +2
Increase passenger car density by factor of 2 +4
Increase density of all sources by factor of 2 +5
Increase passenger car density by factor of 4 +8
I I
80
60
Jamboree at Ford Road CN EL 75.3
70
60
�E
Pacific Coast Highway at Boyside CNEL 77.9
z
C4 0
4)
-F I 1 11
70 ,,,4,H+
N 0' Z;—O
2 60
Pacific Coast Highway at Dover CNEL 77.2
0^
70 000�
601 1 1 1 1 1 1 1 1 1 T1 -- I
Newport Blvd. at Hospital Road CNEL 80.5
80
70
F
60
8 8 8 8
Time of Day in Hours
Irvine at Francisco CNEL 75.6
Figure 2. Dolly Variations of,Nolse-at'Five'Lacatlons
12
These data indicate that drastic increases of traffic flow must occur before large
changes can occur in the residual noise levels. Not so obvious is the fact that if all
sources increased by a factor of 2, there would be no 45 decibel contour between
Jamboree Road and Irvine Avenue except as the noise was attenuated by the bluffs.
Isabella Terrace would be exposed to the 59 decibel contour and traffic noise would
be clearly audible above 'other ambient sounds.
AMBIENT NOISE IN QUIET AREAS
Three "quiet" locations within the City were chosen for monitoring of ambient noise
levels. These locations were chosen as being deep in residential areas not affected
by traffic on the main aerterials. The three locations chosen were: (1) San Bernardino
at l5th Street, (2) Seaward Road at*Isabella Terrace, and (3) Amethyst Avenue along
the south Boyfront walkway. In these areas, one hour measurements were made during
the daytime, evening, and nighttime hours to produce a total of nine hours of data.
This data was analyzed in the same manner as was done for all other data reported
above.and the results are tabulated in Table VI.
Table VI
A-Weighted Ambient Noise Level� in Quiet Locations
(dB re 20 IiNlm )
I 5th Street and Isabella Amethyst
San Bernardino Terrace Avenue, South
Daytime 65 33.1 62.3
Evening 60.5 53.9 53.3
Nighttime 49 52.4 49.9
CNEL 63.8 59.5 60.4
The area at Isabella Terrace shows a constant sound I eve[ throughout the day while the
other areas show the normal nighttime reduction. This is due to large numbers of
crickets and other animal noises throughout the measurement periods.
13
PROPAGATION OF HIGHWAY NOISE INTO THE COMMUNITY
The decay of traffic noise with distance from the highway has been extensively studied
and reported upon in Reference 1. Figure 3 is taken from that report and shows the
expected attenuation of A-weighted noise levels with distance for sounds propagating
over level ground. This figure shows considerably heavier weighting associated with
diesel trucks than has been used in this report for Newport Beach. This is because of
the small number of such heavy trucks traveling the highways of the City. With the
exception of Newport Boulevard and, to a lesser extent, the Pacific Coast Highway,
heavy diesel trucks are relatively rare in the City, since through traffic of this type
uses the Son Diego.Freeway. Figure 3 shows a decay of 6 decibels per doubling of
distance for decay of noise sources of this type for"the first 500 feet. At greater dis-
tancesr excess attenuation due to ground absorption, refraction, air absorption and
other factors causes an increase in the decay rate. It must be noted that the data of
Figure 3 has been extrapolated to very low levels (30 decibels) and that measurements
of actual noise cannot be made at such low levels because other noises in the vicinity
of the microphone mask the traffic noise.
The Single Event Noise Exposure Level (SENEL) can be derived from the data of Figure
3 by use of Equation 4.
SENEL = L i(R) + 10 Log
A 12 V] dB (4)
where
L A(R) = A-weighted noise level at the distance R
R = Distance in feet
V = Speed of vehicle in feet/second
Since, for a given vehicular speed, the ratio of P'/V doubles every time R doubles,
the second term of Equation 4 increases by 3 decibels with each doubling of distance.
14
90
Oaq�'-
S
80 Light Helicopter
z
0 "'
Diesel
I ruck
70
>
60 .......
0
W
z Newport
W
Passenger Car Blvd.
A
50
40
II I...............................
10 100 1000
Distance in Feet
Figure 3. Variation in Typical Noise Levels vs. Distances
For Several Transportation System Categories
1.5
The first term decreases by 6 decibels in this same doubling of distance so that the net
result is a 3 decibel decrease in SENEL for each doubling of distance. Thus, the total
energy intercepted by a receiver at distance does not decay as rapidly as does the
sound pressure.
Decay measurements were conducted within the City to verify the known data repre-
sented by Figure 3 and to evaluate the effects of perturbations imposed on the sound
path by buildings, hills, and cliffs characteristic to Newport Beach. Measurements of
of real traffic noise are difficult as mentioned above because of local noise sources
masking the street noise. However, one such measurement was made at the corner of
Newport Boulevard and Hospital Road, moving west on Hospital Road. Figure 4 is a
photograph of the area studied and it shows a second branch of Newport Boulevard
approximately 160 feet west of the main highway. The measurements were made by
recording five-minute samples of noise at varying distances from the curb of the main
highway and performing the same .integration techrkique to obtain the total energy level
as has been used before. This technique tends to minimize the contributions of local
noise sources so that the traffic noise under study dominates to greater distances. This
data is also imposed upon Figure 3 and shows general agreement.with the other data
of that figure except at 160 feet where the secondary road becomes a major source of
interference.
The interference caused by local noise sources necessitated the use of another tech-
nique for studying attenuation of sound from traffic noise. Accordingly, an impulse
noise source was constructed to simulate the traffic noise. This source was designed to
periodically discharge a high voltage capacitor through the voice coil of a standard
hom loudspeaker. The size of the capacitor and voltage applied was adjusted to
produce a pulse having a spectral output which closely approximates the spectrum of
automobile traffic when it is modified by "A" weighting of the sound level meter.
Figure 5 shows a comparison of the one-third octave spectrum of the pulse generated
with the octave spectrum of automobile traffic as modified by A-weighting. Both
spectra have been matched at 1000 Hertz. The actual level radiated by the impulse
16
Ist
IR FOODS
Figure 4. Intersection of Newport Boulevard and Hospital Road
17
'0"
Auto Traffic
(Octaves)—\_
10 dB
I mplil, nerator
(1/3 Octaves)
100 2 5 1 600 2 5 WOO 2
Frequency in Hertz
Figure 5. Spectral Output of Impulse Sound Generator
Compared with A Weighted Automobile Traffic
VAU LABORMU�
18
generator is considerably higher than the traffic noise with peak levels of 146 decibels
(re: 20 IAN/m 2) four feet from the source. Such levels are sufficiently high so that a
meter designed to respond to impulse noise is fully capable of tracing the signal from
146 to 80 or even 70 decibels. It is thus possible to determine decay rates at manly
locations where traffic noise would be lost in the ambient noise. A total of 32 differ-
ent locations within the City were examined by this method to determine decay rates
In the presence of various obstacles. Table VII 'lists these locations with remarks
concerning them.
The results of the impulse noise tests are illustrated in Figures 6, 7, and 8. The 32
sites have been subjectively divided into three general groups to reflect three differ-
ent types of terrain. Figure 6 includes all sites judged to be flat and straight so that
there was no obstruction of line-of-sigkt between the source and receiver. Figure 7
groups those sites where the source could not always be seen from the receiver, but
there were no abrupt changes. A gentle hill or curve would be reported in this group.
Figure 8 shows the results of tests which included going around a sharp corner or over
the brow of a sharp embankment or behind a'building. Thus, site 19 (Crown Drive at
Mac Arthur Boulevard) involved an embankment at the road and two wooden fences
quite close to Mac*Arthur so the sound from the generator decreased 60 decibels
between four feet and 100 feet. On the other extreme, it was possible to trace the
signal for 1000 feet north on Marigold Street from the Pacific Coast Highway.
The band average shown in Figure 6 was converted to a,SEN EL average by use of
Equation 4 and this was used to plot most of the contours on Figure I. Where geo-
graphical features such as highway cuts (such as Mac Arthur Boulevard at Port West-
bourne and Newport Boulevard at Hospital Road) dictated that more severe attenuation
was in order, the curves of Figures 7 and 8 were used to modify the contours.
The contours for high levels are seen to be very close to the road. Lower level contours
spread.on an antilogorithmic scale as would be expected so that the distance between
45 and 50 dB contours is much greater than the distance between 65 and 70 dB contours.
19
MMMMMM M M
+20
+10
PC,
0
:2 -10
Ix
Design Curve
-20
t>
Site
4A, B
13
-30 — o 3
2 A, B
I A, B
13 00
-40 _ 17 A, B I>
t> 12 A, B
V 11
-50 10 A, B
10 Distance, Feet 100 1000
Figure 6. Attenuation of Simulated A-Weighted Traffic Noise in Open Generally Flat Areas
+20
El
A
+10
El
V
0
I>
Design Curve
-10
A
V
Ln Site
El
-20 0 5 A, B
6 A, B V V
E3
A 7 A A
0
-3o - o 15
0 13
0
16 A, B El V 0
-40 - V 14 Ar B VO
18
El 9 A, B El 0
V
-50 , 1 1 1 -- 1
1 10 Distance, Feet 100 1000
Figure 7. Attenuation of Simulated A-Weighted Traffic Noise in Gently Sloping or Curving Areas
+2 01
0
+10
13
0 0
0
0 U Design Curve
0
-10
-20
0 0
-30 — Site #
c3 7 B 0
0 8
-40 — A 19 0
0 20
-501
1 10 Distance, Feet 100 1000
Figure 8. Attenuation of Simulated A-Weighted Traffic Noise in.Areas Having Sharp Curves and Bluffs
Table VII
List of Sites Chosen for Measurement of Sound Decay in Newport Beach
Site Location Remarks
IA Balboa Boulevard and Alvarado Street,
going south
1B Balboa Boulevard and Alvarado Street,
going north
2A Balboa Boulevard at 14th Streett Near grammar school
going south
2B Balboa Boulevard at l4th Street,,
going north
3 City,Hall — Newport Boulevard at - Near City Hall
32nd Street, going west
4A Balboa Boulevard at 38th Street,
going southwest
4B Balboa Boulevard at 38th Street,
going northeast
5A Pacific Coast Highway at Lugonia,
going south
5B Pacific Coast Highway at Lugonia, Near edge of town
going north
6A Hospital Road and Newport Boulevard,
going east
6B Hospital Road and Newport Boulevard, Near hospital
going west
7A Cliff Drive at Irvine, going north Includes knol I
7B Cliff Drive at King Road, going south Right angle turn
8 Irvine Avenue and Francisco Drive, Residential
southwest
9A Morning Canyon Road and Pacific Residential —curves
Coast Highway, going south
9B Morning Canyon Road and Pacific Residential — curves
Coast Highway, going north
IOA Marigold and Pacific Coast Highway, 1000 foot measurement
north
23
Table VII (Continued)
Site Location Remarks
10B Marigold and Pacific Coast Highway,
south
11 Pacific Coast Highway and Begonia, Residential
going south
12A Pacific Coast Highway and Patolita, Open plowed ground
going north
12B Pacific Coast Highway and Patolitat Residential
going south
13 Dover at 17th Street, going east Parking lot
14A Jamboree and San Joaquin Hills, Apartment
going east
14B Jamboree and San Joaquin Hills, Climbing Hill
going west
15. Pacific Coast Highway and Dover,
going north
16A Bayside and Pacific Coast Highway,
going south
16B Boyside and Pacific Coast Highway, Trailer park
going north
17A Jamboree and Eastbluff Drive, Residential
going north
17B Jamboree and Ford Road, going west Open space
18 Jamboree and Bison Avenue, Residential
going east
19 Mac Arthur Boulevard and Crown Residential
Drive, going west
20 Mac Arthur Boulevard and Port Clear, then residential
Westbourne, going west
24
Thus, while the data of Figure 2 show very high levels at curbside, the levels only a few
feet from the roadways becomes quite tolerable so that the contours of the highway
noise near Isabella Terrace drop to as low as 50 decibels while the animal noises are
slightly higher (Table V).
The noise contours are continued on a theoretical basis down to 45 decibels near
schools and' hospitals. These contours are extended well beyond any actual measure-
ment capability, but they represent reasonably good extrapolations of the noise that
might be expected. These theoretical spreading losses have also been modified where
large geographical perturbations exist. The contours near the Corona del Mar High
School are unmodified by geographical considerations until the 45 decibel contour
intersects the backbay bluff and then the curve follows the bluff line. A similar
situation exists at the Hoag Memorial Hospital where the 60 decibel curve tends to
follow the top edge of the bluff there. Beyond this edge, the contours are seen to show
a rapid reduction in noise level. Thus, the hospital grounds are protected from the
full impact of the heavy traffic on Newport Boulevard. The upper stories of the
hospital are exposed to this noise, however.
Contours between Jamboree Road and MacArthur Boulevard, north of Ford Road, have
been continued down to 55 decibels to illustrate, in a small area, the natural exten-
sion of contours for the entire area. it is also illustrated that there is no point within
this area where the traffic noise drops to as low as 50 decibels. It is probable that
isolated points within the area may be found where traffic noise does become inaudible,
but the general area is al I above 50 dB.
HELICOPTER NOISE
Police Helicopter
The Newport Beach Police Department operates a helicopter in the normal course of
police duties over the City. The helicopter patrols a varying route at varying speeds,
25
with occasional high speed runs for emergency work. For this reason, it is not possible
to determine accurate duration weighted sound pressure levels over any given area of
the City. Table WI tabulates data taken by the Newport Beach Police Department at
several different locations in, the City and at several different altitudes. This parti-
cular helicopter has been treated for reduced noise emission so that the levels measured
are considerably lower than those reported in Figure 3 for average unmuffled light
helicopters.
Table VIII
A-Weighied Noise Measurements from Police Helicopter
Tuesday, 2/13/73, Wind Velocity 3 Knots from the North/Northwest
a. 16th Street and Dover Drive (open area). Ambient Noise Level 54 dB(A)
NBPD Helicopter 500 feet altitude 69 dB(A)
NBPD Helicopter 800 feet altitude 65 dB(A)
b. Shorecliffs Drive at Easit End (residential area, close in and near the
canyon). Ambient Noise Level 55 dB(A).
NBPD Helicopter 500 feet altitude 70 dB(A)
NBPD Helicopter 800 feet altitude 66 dB(A)
Wednesday, 2/14/73, Wind Velocity 4 Knots from the Southwest
0. 16th Street and Dover Drive. Ambient Noise Level 55 dB(A)
NBPD Helicopter 500 feet altitude 71 dB(A)
NBPD Helicopter 800 feet altitude 65 dB(A)
NBPD Helicopter 1500 feet altitude 61 dB(A)
b. Shorecliff Road at East End. Ambient Noise Level 52 dB(A)
NBPD Helicopter 500 feet altitude 71 dB(A)
NBPD Helicopter 800 feet altitude 64 dB(A)
NBPD Helicopter 1500 feet altitude 60 dB(A)
Both days had scattered clouds, however clear skies in the immediate area
of the tests. All dB(A) readings were taken on a General Radio Company,
Type 1561A Precision Sound Level Meter using the A-weighting scale.
26
The data of Table VIII shows a consistent roll-off with distance- For example, if
the helicopter passed over a given point at a height of 800 feet of a speed of
60 miles per hour once per hour, it would produce -a SENEL of 80.5 or an HNL of 45
dB. If more flights were made, the HNL would increase by 3 decibels each time the
number of flights was doubled. Such a flight during nighttime hours would carry a
10 dec'ibel penalty bringing the line directly below the flight path to an HNL of 55
dB. This is,comparable with the ambient levels found in many areas of the City. A
point one-half mile from the flight path would experience a weighted HNL of 50 dB
and a SENEL of 75 dB. This is comparable with that of an automobile passing once
each hour.
Military Helicopter
An attempt was made to determine the effects of military helicopters flying over the
City. Contact was made with the military authorities with the intention that several
military helicopters would fly over a specified location within the City in a specified
time period. A monitoring station was set up under the planned flight path at the
northwest comer of Big Canyon Reservoir. During the appointed two-hour period, a
single military helicopter flew within range of the microphone, but on a path that
was several hundred yards to the east of the monitoring point. Distance and speed
could not be estimated. This one recording showed a peak level of 78 decibels and a
duration of 13 seconds (at the 10 dB down points) for a SENEL of approximately 86
decibels. One flight per hour would contribute 51 decibels to the local HNL, This
would not be a large contribution to the HNL of even the quieter areas of the City
(Table VI), but 10 flights in one hour would contribute a great deal. If these flights
occurred at nighttime, they would be cause for great concern.
METHODS AND EFFECTS OF NOISE REDUCTION
1. Barriers
It has been seen during this program that the consideration of barriers as a
method of reducing the intrusion of highway noise into residential areas can be
27
of some use. At points where highways go through narrow deep cuts, the con-
tours of Figure I are sharply compressed, and this has been particularly true
around the Hoag Memorial Hospital. Reference 2 has investigated,barriers to
traffic noise and has shown that considerable reductions may be gained through
the use of such barriers. However, the actual reductions obtained were any-
where from 6 to 10 decibels less than those which might be expected from theo-
retical considerations. This is because of scattering of sound by wind turbulence
and other atmospheric conditions which affect sound propagation. Again,
barriers comparable in size with the embankments described would have con-
siderable effect, but, unfortunately would be quite unsightly and prohibitively
expensive. Some rock walls have been placed along residential areas on
Jamboree Road and other places where such areas are exposed directly to traffic
noise, 'and these are undoubtedly having a good effect.
2. Vehicular Control
The problems presented by roads such as Irvine Avenue, where high speed
traffic is passing directly through residential areas, do not lend themselves
to the use of barriers. For areas such as Irvine Avenue, it is recommended that
the noise sources be more effectively controlled. This might be accomplished
by stringent enforcement of existing speed limits or even through reduction of
these limits, but the correction factors listed in Table III do not indicate that
large reductions of noise can be accomplished through reduced speeds. It is
suggested, though, that strict enforcement of speed laws, combined with close
supervision of sound control devices on the individual vehicles, would reduce
the noise significantly. It was noted during the gathering of noise data within
the City that large numbers of vehicles have modified exhaust systems which
radiate noise levels in excess of 90 dB(A) and sometimes even 100 dB(A) at
curbside. Conversations with homeowners who volunteered information at the
time of data gathering indicate that these people are more sensitive to the high
28
peaks than their time duration would indicate. Even the levels that are exceeded
10 percent of the time (L 10, Table IV) are excessive, but the I percent levels
representr to the homeowners, noise generated by persons who have I ittle or
no regard for the environment. Many of these high peaks are the result of the
modification of exhaust systems in an effort to squeeze the last bit of power
from small engines. Such vehicles attract attention. A primary recommendation
for reduction of present noise level would be more strict control of the small
minority of vehicles generating the highest noise levels. Heavy diesel trucks
might well be restricted from Irvine Avenue to reduce peak levels even though
average levels would be little affected.
3. Zoning Chaiiges
Most construction along the heaviest traveled streets, such as the Pacific Coast
Highway, is commercial . Residencas behind this commercial construction are
therefore protected from the higher noise levels of these streets. However, it
would be considered a drastic step to encourage commercialism along these
streets and it is not compatible with overall land use plans. A more practical
zoning approach to transportation noise reduction is possible by requiring
sufficient noise reduction in external wall construction of single and multi-family
dwellings facing on busy highways.
29
REFERENCES
1 Wyle Laboratories, "Transportation Noise and Noise From Equipment Powered
by Internal Combusion Engines, " for the Environmental Protection Agency,
Washington, D.C., NTID 300.13, December 31, 1971 .
2. Scholes, W.E., et al, "Barriiers and Traffic Noise Peaks," Applied Acoustics,
Vol. 5, 1972, pp 205-222.
30
APPENDIX A
DERIVATION OF THE HOURLY NOISE LEVEL PER AUTOMOBILE
Table III of the report does not clearly indicate the process used for progressing from
the HNL data measured to the levels that may be expected to be generated by a single
cutom;bile passing once in each hour or HNL*. The physical process involved is to
accumulate the total acoustic energy emitted by the cars passing a given point (really
the energy intercepted by a given microphone) and divide the total number by the
number of cars passing the point to normalize the level to that of a single vehicle. it
must be admitted that this average does not represent any of the possible extremes,
but it has been found to be useful.
When a number is given as a "level," it.has been converted to a decibel scale. That
is, the figure given is equal to ten times the logarithm of the total energy involved.
Thus, a Sound Pressure Level or an Hourly Noise Level has been "logged." A quick
review of logarithms will reveal that if a level is divided by a number of events, the
n th root of the total energy will result, rather than a simple factor. It is necessary,
therefore, either to convert the level back into a number, or convert the number of
events into a level. If we have a traffic count of 1000 cars, then we may say that we
have a traffic level of ten times the logarithm of 1000 or TL = 10 Log TC = 30 dB
(spoken as traffic level equals 10 Log traffic count). Given the traffic level, then,
it may be simply subtracted from the sound level to obtain the level that would result
from a single automobile.
It can be shown that a heavy diesel truck traveling at freeway speeds will generate
almost ten times the acoustic energy that an automobile will generate under similar
conditions. However, for traffic conditions existing in Newport Beach, most trucks
are small and speeds are low. For these reasons, an arbitrary factor of two is used to
relate the noise of a truck to that of a standard automobile. That is, one truck equals
two cars. At this point, it is possible to obtain a traffic count consisting of the number
of cars plus two times the number of trucks, take the logarithm of it, and multiply by
ten. An equation may be written to describe this action:
A-]
HNL* = HNL - 10 Log (N C + 2N t + C I
where
HNL* = Normalized HNL corrected for the number of events
N c = Number of automobiles passing a given point
Nt = Number of trucks passing a given point
C I = Constant chosen to normalize road conditions (see Table A-1
and notes)
Table A-1 is an expansion of Table III, listing the' HNL, 10 Log(Nc + 2N d, the
corrections (C,) applied, and the final HNL* obtained. The correction factor (C,)
would be zero if all the sites were similar; however, some of the sites involved stop
signs, hills, high speed, and other conditions that would dictate change. Thus, a set
of correction factors was derived to increase the average if it represented cars
operating at less than normal speeds on level ground, or to decrease the average if it
represented cars operating at high speeds, climbing grades, or otherwise generating
more than normal noise.
These correction terms are listed in the notes of Table A-1 and are applied as Column
5 of Table A-1 to the averages of Column 4, giving Column 6. A simple average of
the numbers obtained in Column 6 gives the final value of 40.7 or approximately 41
decibels representing the HNL* that would result from passage of a single car in the
one hour under standard conditions. Under the assumptions of this derivation, one
truck passing each two hours would give the some average level.
The data of Table A-] may be used in reverse to obtain the HNL for any given hour of
traffic count. It may be used in either of two different ways. It is possible to use the
location data of Column 4, Table A-1, to determine the HNL*. This column would be
used where a location listed corresponded closely to the location under investigation.
A-2
Table A-I
Derivation of HNL*
HNL HNL C HNL*
Location dB 10 Log(NC+2N t dB dB' dB
Pacific Coastflighway and 74 32.7 41.3 -1 40.3
Marigold
Pacific Coast Highway and 76.8 34.2 41.3 0 42.6
Patolita
Pacific Coast Highway and 73.6, 36.5 37. 1 +3 40.1
Bayside
Pacific Coast Highway and 76.2 32.5 43.7 -2 41.7
Dover
Pacific Coast Highway and 73.3 33.6 39.7 0 39.7
Lugonia
Balboa and 14th Street 70.4 30.4 40.0 0 40.0
Balboa and 38th Street 72.4 27.9 44.5 Out -
Newport Boulevard and 79.8 35.6 44.2 -2 42.2
Hospital Road
Irvine and Francisco 73.7 32.2 41.5 0 41.5
Jamboree and Ford Road 76.8 35.0 41.8 -1 40.8
Jamboree and Son Joaquin Hills 73.2 34.7 38.5 0 38.5
Doverand 16th Street 69.6 32.3 37.3 +2 39.3
MacArthur and Port Westbourne 78.2 33.7 44.5 -2 42.5
Average 41.4 40.7
1 HNL* = HNL - 10 Log (Nc + 2 Nt)
cks
Nc Number of Cars, Nt Number of Tru'
Corrections
C 1 +2 dB for low'speed or downhill C 1 -1 dB if cars are climbing a 2%
+3 dB for cars idling for long periods grcide
+10 Log d/20 where distance to traffic -2 dB if many trucks
is greater than 20 feet -1 dB if cars are starting
-2 dB for high speed
A-3
Then, using information from Column 4, an HNL* would then be added to 10 times the
logarithm of the number of cars (and trucks, if applicable) to obtain the expected
Hourly Noise Level for that location at the time of the traffic count. The CNEL or
daily noise level may then be obtained by determining the hourly traffic counts and
HNL's for the entire day, using the proper weighting constants for HNL's obtained
during evening and night hours. The 24-hour total of HNL data is added in accordance
with Equation 2.
CNEL = 10 Log 1 [ELog-I HNLD + 3 E Log-' HNLE + 10 ELog-I HNLNj (2)
where
HNLD = HNL during daytime hours (0700-1900)
HNLE = HNL during evening hours (1900-2200)
H NLN = H NL during nighttime hours (2200-0700)
Annual CNEL data would, of course, be based upon annual traffic counts and would
consist of adding all daily CNEL's together and subtracting 25.6 (10 Log 365). The
second method would be to use the average number of 40.7 as the HNL* and add the
correction fact6rs of Column 5 (using the opposite algebraic sign) that apply to the
area under study and add 10 times the logarithm of the traffic count.
If Hourly Noise Levels are not desired, it is only necessary to determine the total
traffic counts for the daytime hours (0700-1900), the evening hours (1900-2200), and
the nighttime hours (2200-0700). These counts may then be multiplied by one, three,
and ten respectively and then added together to obtain the total weighted count. This
total may then be operated upon to obtain 10 times the logarithm and this added to the
HNL*. This result must then have 13.8 decibels (10 Log 24) subtracted to give the
CNEL for the day. This operation is detailed in Equation 3.
A-4
CNEL = HNL* + 10 Log [Nd + 3N e + '0 Nn] 13.8 +Corrections (3)
where
N d = Number of cars + 2 times number of trucks during day
N = Number of cars + 2 times number of trucks during evening
e
N = Number of cars + 2 times number of trucks during night
it must be noted that the levels of Columns 4 and 6 of Table A-1, and especially their
averages, do not show great variability from point to point, with or without correc-
tions. Thus, for first order approximations of the traffic noise represented by these
measurements, an HNL* may be taken around 41 decibels at curbside. Even truck
counts may be included as cars if the total number of axles is divided by two to obtain
traffic count. This is considered possible because of the small truck mix obtained.
if trucks become a large percentage of total traffic, they would, of course, have to be
figured separately.
The use of the foregoing data will serve to estimate hourly, daily, and annual noise
levels at curbside along the main streets of Newport Beach through the use of supple-
mentary traffic data.
A-5