4.6 NOISE
4.6.1 EXISTING SETTING
BACKGROUND AND TERMINOLOGY
This section provides the environmental setting and impact assessment for noise in the City of
San Mateo. This includes the effects of noise from future development allowed by the proposed
General Plan, both new noise sources and increased traffic.
A summary of the noise and vibration analysis related to the redesignation of Fifth Avenue to a
collector street is provided here while the impact analysis is detailed in the Traffic and Circulation
section of the EIR.
Basic Concepts of Environmental Noise
Noise is commonly defined as unwanted sound. Environmental noise is a part of modern society,
such as noise from transportation vehicles, machinery, and amplified sound. People can tolerate
a certain amount of noise, but excessive levels become a nuisance and can ultimately result in
hearing impairment. Three dimensions of environmental noise are important in determining
subjective response. These are:
•
•
•
The intensity or level of the sound
The frequency spectrum of the sound
The time-varying character of the sound
Noise level or intensity is measured in decibels (dB), and ranges from 0 dB, which is the threshold
of hearing, to 120 dB, which is the threshold of pain.
The “frequency” of a sound refers to the number of complete pressure fluctuations per second in
the sound. The unit of measurement is the cycle per second (cps) or hertz (Hz). Most sounds that
we hear in the environment do not consist of a single frequency, but rather of a broad band of
frequencies, differing in level. The combination of the frequency and level content of a sound is
called its sound spectrum. A sound spectrum for engineering purposes is typically described in
terms of octave bands, which separate the audible frequency range (for human beings, from
about 20 to 20,000 Hz) into ten segments.
Many rating methods have been devised to permit comparisons of sounds having quite different
spectra. Surprisingly, the simplest method correlates with human response practically as well as
more complex methods. This simple method consists of evaluating all of the frequencies of a
sound in accordance with a “weighting” that progressively de-emphasizes the importance of
frequency components below 1000 Hz and above 5000 Hz. This frequency weighting reflects the
fact that human hearing is less sensitive at low frequencies and at extreme high frequencies
than at mid-range frequencies.
The weighting system described above is called “A”-weighting, and the level so measured is
called the “A-weighted sound level” or “A-weighted noise level.” The unit of A-weighted sound
level is abbreviated “dB”; all noise levels presented are A-weighted. In practice, the sound level
is conveniently measured using a sound level meter that includes an electrical filter
corresponding to the A-weighting spectrum. All U.S. and international standard sound level
meters include such a filter. Typical sound levels found in the environment and in industry are
shown in Figure 4.6-1.
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4.6 NOISE
FIGURE 4.6-1
SOUND LEVEL IN A-WEIGHTED DECIBELS (DB)
HOW LOUD IS LOUD?
Jet takeoff (at 200')
120
Rock music band
110
Jackhammer (at 25')
100
Motorcycle accelerating (at 25')
90
Power lawn mower (at 20')
80
Steady urban traffic (at 25')
70
Normal conversation (at 3')
60
Daytime street, no nearby traffic
50
Inside average residence
40
Inside quiet home
30
Rustling leaves
20
Mosquito (at 3')
10
0
Threshold of pain
Threshold of hearing
Every increase of 10 dB doubles the perceived loudness of noise. For example, a motorcycle accelerating (90 dB) seems twice as loud as
a power lawn mower (80 dB).
Although a single-number sound level system might adequately describe environmental noise at
any instant in time, community noise levels vary continuously throughout the day. Most
environmental noise is a conglomeration of distant noise sources, which results in a relatively
steady background noise having no identifiable source. These distant sources might include
street traffic, wind in trees, industrial activities, etc. As natural forces change or as human activity
follows its daily cycle, the sound level can vary slowly from hour to hour. Superimposed on this
slowly varying background is a succession of identifiable noisy events of brief duration. These
may include nearby activities such as individual vehicle passbys, aircraft flyovers, etc. that cause
the environmental noise level to vary from instant to instant.
To describe the time-varying character of environmental noise, statistical noise descriptors were
developed. “L10” is the A-weighted sound level equaled or exceeded during 10 percent of a
stated time period. The L10 is considered a good measure of the maximum sound levels caused
by discrete noise events. “L50” is the A-weighted sound level that is equaled or exceeded 50
percent of a stated time period; it represents the median sound level. The “L90” is the A-weighted
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4.6 NOISE
sound level equaled or exceeded during 90 percent of a stated time period and is used to
describe the background noise level.
As it is often cumbersome to quantify the noise environment with a set of statistical descriptors, a
single-number metric called the average sound level or “Leq” is now widely used. The term “Leq”
originated from the concept of a so-called “equivalent” sound level that contains the same
acoustical energy as a varying sound level during the same time period. In simple but accurate
technical language, the Leq is the average A-weighted sound level in a stated time period. The
Leq is particularly useful in describing the subjective change in an environment where the source
of noise remains the same but there is change in the level of activity. Widening roads and/or
increasing traffic are examples of this kind of situation.
In determining the daily measure of environmental noise, it is important to account for the
different response of people to daytime and nighttime noise. During the nighttime, exterior
background noise levels are generally lower than in the daytime; however, most household
noise also decreases at night, thus exterior noise intrusions again become noticeable. Further,
most people are trying to sleep at night and, hence, are more sensitive to noise. To account for
human sensitivity to nighttime noise levels, a special descriptor was developed. The descriptor is
called the Ldn or DNL (Day-Night Average Sound Level), which represents the 24-hour average
sound level with a penalty for noise occurring at night. The Ldn computation divides the 24-hour
day into two periods: daytime (7:00 am to 10:00 pm); and nighttime (10:00 pm to 7:00 am). The
nighttime sound levels are assigned a 10 dB penalty prior to averaging with daytime hourly
sound levels.
Another 24-hour noise descriptor is the CNEL (Community Noise Equivalent Level). This descriptor
is similar to the Ldn, but includes a 5 dB penalty for noise occurring between the hours of 7:00 pm.
to 10:00 pm in addition to the 10 dB nighttime penalty. Typically, there is less than 1 dB of
difference between Ldn and CNEL levels.
For suburban/rural highways and most roadways, the average noise level during the peak traffic
periods (i.e., rush hour) is approximately equal to the Ldn. For urban highways, the Ldn is typically
one to two dB higher than the peak hour Leq.
Noise Attenuation
Noise from stationary “point” sources, including stationary mobile sources such as idling vehicles,
attenuates (lessens) at a rate of 6 dB to 7.5 dB per doubling of distance from the source,
depending upon environmental conditions (e.g., ground absorption, atmospheric conditions).
Widely distributed noises, such as a large industrial facility spread over many acres or a street
with moving vehicles (a “line” source), would typically attenuate at a lower rate, approximately
3 to 4.5 dB per doubling of the distance from the source, again, depending upon environmental
conditions (Caltrans, 1998). Noise from large construction sites would have characteristics of
both point and line sources, so attenuation would generally range between 4.5 and 7.5 dB per
doubling of distance.
Noise levels may also be reduced by intervening structures. For example, a single row of
buildings between the receptor and the noise source reduces the noise level by about 5 dB to
10 dB. Structures also act to insulate people inside these structures from exterior noise. Older
home construction methods generally provide a reduction of exterior-to-interior noise levels of
about 20 dB with closed windows, while the reduction in newer homes is generally 30 dB or
more.
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4.6 NOISE
EFFECTS OF NOISE ON PEOPLE
The effects of noise on people are summarized below:
•
Annoyance is the most difficult of all noise responses to describe. Annoyance is a very
individual characteristic and can vary widely from person to person. What one person
considers acceptable can be intolerable to another of equal hearing capability. For
example, some people like the sound of trains, while others do not.
•
Physiological responses are those measurable noise effects on the human body, such as
changes in pulse rate, blood pressure, etc. While such effects can be induced and
observed, the extent to which these physiological responses cause harm or are a sign of
harm is not known.
•
Sleep interference is a major concern with respect to transportation-generated noise.
Sleep disturbance studies have identified interior noise levels attributed to transportation
noise as a key factor of sleep disturbance. However, sleep disturbance does not
necessarily equate to awakening from sleep; rather, it can refer to disruption of the sleep
pattern and stages of sleep. Train and aircraft noise is a major source of complaint.
•
Speech/learning interference is one of the primary concerns associated with
environmental noise. Normal conversational speech is in the range of 60 to 66 dB; steady
noise above 45 dB or intermittent noise above 55 dB can interfere with speech and
learning. Depending on the distance between the speaker and the listener, raised voice
levels may be required to overcome the background (e.g., transportation induced)
noise.
•
Potential hearing loss is commonly associated with occupational exposures in heavy
industry or very noisy work environments. Noise levels in neighborhoods, even near very
noisy airports, are not sufficiently loud to cause hearing loss.
The sound levels associated with environmental noise usually only produce effects in the first four
categories. Unfortunately, there has never been a completely predictable measure for the
subjective effects of noise nor of the corresponding reactions of annoyance and dissatisfaction.
This is primarily because of the wide variation in individual thresholds of annoyance and
habituation to noise over time.
Thus, an important factor in assessing a person's subjective reaction is to compare the new noise
environment to the existing noise environment. In general, the more a new noise exceeds the
existing noise environment, the less acceptable the new noise will be judged to be.
With regard to increases in noise level, knowledge of the following relationships will be helpful in
understanding the quantitative sections of this analysis:
•
Except in carefully controlled laboratory experiments, an increase of only 1 dB in sound
level cannot be perceived.
•
Outside of the laboratory, a 3 dB increase is considered a just-noticeable difference.
•
An increase in level of at least 5 dB is required before any noticeable change in
community response would be expected.
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4.6 NOISE
•
A 10 dB increase is subjectively heard as approximately a doubling in loudness, and
would almost certainly cause an adverse community response.
These relationships occur because of the logarithmic nature of sound and the decibel system.
The human ear perceives sound in a non-linear fashion; hence, the decibel scale was
developed. Because the decibel scale is based on logarithms, two noise sources do not
combine in a simple additive fashion, rather they combine logarithmically. For example, if two
identical noise sources produce noise levels of 50 dB, the combined sound level would be 53 dB,
not 100 dB.
EXISTING NOISE CONDITIONS IN THE PLANNING AREA
Noise exposure in the City of San Mateo is dominated by traffic on highways and major arterial
roads and trains on the Southern Pacific (SPRR)/Caltrain rail line. Aircraft activity associated with
San Francisco International Airport does not significantly affect noise levels in San Mateo,
although some neighborhoods in the northeastern portion of the City are impacted by the
airport approach path. Localized noise sources include the San Mateo County Fairgrounds,
when events are being held. Generally, noise created by manufacturing uses does not have a
major impact on the community, although occasional complaints are received from neighbors
immediately adjacent to the manufacturing sites.
Traffic Noise
Traffic noise levels depend primarily on the speed of the traffic and the volume of trucks. The
primary source of noise from automobiles is high-frequency tire noise, which increases with
speed. Trucks and older automobiles produce engine and exhaust noise, and trucks can also
generate wind noise. Tire noise from cars is produced at ground level (i.e., where the tire
contacts the road), whereas truck noise can be generated at a height of ten to fifteen feet
above the road, depending on the height of the exhaust pipe(s) and engine. As a result, sound
walls are not as effective at reducing truck noise unless they are very tall.
In San Mateo, the primary sources of traffic noise are US 101, Highway 92, El Camino Real,
Hillsdale Boulevard, Alameda de las Pulgas, South Delaware Street, Peninsula Avenue, Poplar
Avenue, 3rd Avenue/4th Avenue/J Hart Clinton Drive, and Norfolk Street.
The Federal Highway Administration’s Highway Traffic Noise Model (FHWA-RD-77-108) was used
to predict traffic noise levels along major arterials and freeways in San Mateo. Table 4.6-1
provides a summary of the traffic data and distance to the Ldn 60 dB and Ldn 70 dB noise
contours for the present day condition. Where feasible, the calculated noise levels were crosschecked with the measured noise levels provided in the Community Noise Survey section of this
analysis. Figure 4.6-2 illustrates the present day traffic noise contours.
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4.6 NOISE
TABLE 4.6-1
PRESENT DAY TRAFFIC VOLUMES AND DISTANCES TO LDN TRAFFIC NOISE CONTOURS
Street Name
Segment
Volume
Speed
Truck
(peak hour)
(mph)
Percentage
Ldn at
50
Feet
Distance, in feet,
(dB)
70 dB
60 dB
to Ldn Noise
Contours
North/South Streets
1
El Camino Real
North of 2nd Avenue
2752
35
2.00%
69.6
47
220
2
El Camino Real
South of 2nd Avenue to 17th/Bovet
2551
35
2.00%
69.3
45
209
3
El Camino Real
South of 17th-Bovet to 28th Avenue
3457
35
2.00%
70.6
55
256
4
El Camino Real
South of 28th Avenue to Hillsdale Boulevard
3199
35
2.00%
70.3
52
243
5
El Camino Real
South of Hillsdale Boulevard to 42nd Avenue
2247
35
2.00%
68.8
41
192
6
El Camino Real
South of 42nd Avenue
2572
35
2.00%
69.4
45
210
7
Delaware St.
North of Poplar Street
624
25
2.00%
61.2
13
60
8
Delaware St.
South of Poplar Street to 3rd Avenue
962
25
2.00%
63.1
17
81
9
Delaware St.
South of 3rd Avenue to 9th Avenue
1219
25
2.00%
64.1
20
94
10
Delaware St.
South of 9th Avenue to 19th Avenue
1269
25
2.00%
64.3
21
97
11
Delaware St.
South of 19th Avenue to 25th Avenue
1591
25
2.00%
65.3
24
113
12
Delaware St.
South of Saratoga Avenue
1389
25
2.00%
64.7
22
103
13
Alameda de las Pulgas
North of 20th Avenue
1733
30
2.00%
67.0
32
147
14
Alameda de las Pulgas
South of 20th Avenue
2368
30
2.00%
68.4
39
181
15
US-101
All of San Mateo (with ten-foot tall sound walls)
16800
55
3.74%
84.9
296
2042
16
Highway 280
All of San Mateo
11400
65
1.70%
84.1
433
2011
17
3rd Avenue
East of Mariners Island Boulevard
1277
30
2.00%
65.7
26
120
18
3rd Avenue
East of Norfolk Street to Mariners Island Boulevard
2402
30
2.00%
68.4
39
183
19
3rd Avenue
East of Humboldt Street to Norfolk Street
1666
30
2.00%
66.9
31
143
20
3rd Avenue
East of Delaware Street to Humboldt Street
637
30
2.00%
62.7
16
75
21
3rd Avenue
East of El Camino Real to Delaware Street
801
30
2.00%
63.7
19
88
22
3rd Avenue
West of El Camino Real
703
30
2.00%
63.1
17
81
East/West Streets
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4.6 NOISE
TABLE 4.6-1
PRESENT DAY TRAFFIC VOLUMES AND DISTANCES TO LDN TRAFFIC NOISE CONTOURS
Street Name
Volume
(peak hour)
Segment
Speed
(mph)
Truck
Percentage
Ldn at
50
Feet
(dB)
Distance, in feet,
to Ldn Noise
Contours
70 dB
60 dB
23
4th Avenue
East of Humboldt Street
1503
30
2.00%
66.4
29
134
24
4th Avenue
East of Delaware Street to Humboldt Street
995
30
2.00%
64.6
22
102
25
4th Avenue
East of El Camino Real to Delaware Street
1225
30
2.00%
65.5
25
117
26
4th Avenue
West of El Camino Real
598
30
2.00%
62.4
16
72
27
9th Avenue
East of Delaware Street
549
25
2.00%
60.7
12
55
28
9th Avenue
West of Delaware Street
372
25
2.00%
59.0
9
43
29
31st Avenue
West of El Camino Real
446
25
2.00%
59.8
10
48
31
42nd Avenue
West of El Camino Real
1037
25
2.00%
63.4
18
85
33
Hillsdale Blvd.
East of Norfolk Street
3724
35
2.00%
71.0
58
269
34
Hillsdale Blvd.
East of US-101 to Norfolk Street
2746
35
2.00%
69.6
47
219
35
Hillsdale Blvd.
East of Saratoga Drive to US-101
2370
35
2.00%
69.0
43
199
36
Hillsdale Blvd.
East of El Camino Real to Saratoga Drive
2620
35
2.00%
69.4
46
213
37
Hillsdale Blvd.
East of Alameda de las Pulgas to El Camino Real
2346
35
2.00%
69.0
43
198
38
Hillsdale Blvd.
East of Campus Drive to Alameda de las Pulgas
1990
35
2.00%
68.2
38
177
39
Hillsdale Blvd.
West of Campus Drive
1342
35
2.00%
66.5
29
136
40
Peninsula Ave.
East of Delaware Street
1309
30
2.00%
65.8
26
122
41
Peninsula Ave.
West of Delaware Street
1430
30
2.00%
66.2
28
129
42
Poplar Ave.
East of Delaware Street
878
25
2.00%
62.7
16
76
43
Poplar Ave.
West of Delaware Street
909
25
2.00%
62.9
17
78
44
Highway 92
101 to San Mateo Bridge
11400
55
4.50%
83.3
383
1777
45
Highway 92
El Camino to 101
8900
55
2.40%
81.4
289
1342
46
Highway 92
Ralston to El Camino Real
7000
55
4.55%
81.1
276
1283
47
Highway 92
280 to Ralston
8100
55
4.55%
81.8
306
1419
Source: Hexagon Transportation Consultants, 2008; Caltrans, 1998; Charles M Salter Associates Inc., 2009.
Note: Noise levels do not take into account noise attenuation provided by intervening buildings.
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4.6 NOISE
Rail Noise
The Southern Pacific Railroad Line runs adjacent to El Camino Real in the southern portion of the
City and jogs east slightly at Hillsdale Boulevard and runs along the western border of Bay
Meadows. North of Bay Meadows, the tracks run adjacent to Railroad Avenue until the northern
portion of the City, where they run between North San Mateo Drive and North Claremont Street.
Currently, there are 92 Caltrain commuter trains that pass through San Mateo each weekday.
There are also two freight trains per day that operate six times a week between 7:00 p.m. and
10:00 p.m. from Sunday to Friday. The freight trains originate in South San Francisco and travel to
San Jose and back each evening. There is limited Caltrain activity on the weekends (e.g.,
ballpark trains).
Noise levels for the rail line were calculated using the methodology contained in the Federal
Transit Administration’s Transit Noise and Vibration Impact Assessment manual. It was assumed
that the train’s warning horn was blown within ¼ mile of all grade crossings and stations. Due to
the numerous grade crossings and stations in San Mateo, the train horn dominates the existing
train noise contours shown in Figures 4.6-2.
Aircraft Noise
The northeastern part of the City is somewhat affected by aircraft activity due to nearby San
Francisco International Airport. Typically, aircraft are on approach (i.e., landing) over San
Francisco Bay just to the east of San Mateo. The City is located outside of the Airport’s CNEL
65 dB noise contour.
Other Noise Sources
There is some noise from the industrial/manufacturing land uses situated along the rail line and
occasional noise from the San Mateo County Fairgrounds during events. These sources are
minor, as they are intermittent and only affect adjacent residents. In addition, there are
localized noise sources such as building mechanical equipment and loading docks.
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4.6 NOISE
FIGURE 4.6-2: PRESENT DAY NOISE CONTOURS
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Community Noise Survey
A noise measurement survey was conducted in San Mateo during September 2008 to determine
noise levels throughout the community. The noise survey consisted of long-term (i.e., 24-hour)
noise measurements at ten different locations along major roadways. The noise monitors were
installed at a height of twelve feet above grade. Table 4.6-2 summarizes the noise measurement
locations and measured Ldn; Figure 4.6-3 illustrates the noise measurement locations.
TABLE 4.6-2
NOISE MEASUREMENT LOCATIONS AND RESULTS
Location
No.
Location Description
Dominant Noise Source(s)
Measured Ldn
(dB)
1
Along Bayshore Drive, just north of Rogell
Avenue, 110 feet east of US-101
Traffic on US-101
75
2
170 feet west of El Camino Real centerline at
Notre Dame Avenue
Traffic on El Camino Real
64
3
130 feet south of Highway 92, 850 feet west
of El Camino Real
Highway 92
67
4
20 feet north of the West 20th Avenue
centerline, 860 feet west of El Camino Real
Traffic on West 20th Avenue
67
5
35 feet west of Alameda de las Pulgas
centerline, at Beresford Park
Auto and bus traffic on
Alameda de las Pulgas
67
6
In the southwest Bay Meadows parking lot,
125 feet from the Caltrain tracks
Caltrain passbys and El
Camino Real traffic
72
7
60 feet southwest of the Saratoga Drive
centerline, northwest of Yates Way and east
of Bay Meadows Racetrack
Traffic along Saratoga Drive
65
8
25 feet north of Hillsdale Boulevard
centerline, 375 feet west of Edison Street
Traffic on Hillsdale Boulevard
69
9
End of Oakwood Drive, 220 feet east of
Highway 92
Highway 92
55
10
35 feet northeast El Camino Real centerline,
just north of 41st Avenue
Traffic on El Camino Real and
Caltrain passbys
76
Source: Charles Salter Associates, 2008.
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4.6 NOISE
FIGURE 4.6-3
NOISE MEASUREMENT LOCATIONS
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4.6 NOISE
4.6.2 REGULATORY FRAMEWORK
Federal, state, and local agencies regulate different aspects of environmental noise. Federal
and state agencies generally set noise standards for mobile noise sources such as aircraft and
motor vehicles, while regulation of stationary noise sources associated with industrial,
commercial, and construction activities is left to local agencies. Local regulation of noise
involves implementation of general plan policies and noise ordinance standards. Local general
plans identify general principles intended to guide and influence development plans; local noise
ordinances establish standards and procedures for addressing specific noise sources and
activities.
FEDERAL
Generally, the federal government sets noise standards for transportation-related noise sources
closely linked to interstate commerce. These include aircraft, locomotives, and trucks. The
relevant regulations are summarized below:
Code of Federal Regulations: Federal regulations establish noise limits for medium and heavy
trucks (more than 4.5 tons, gross vehicle weight rating) under 40 CFR [Code of Federal
Regulations], Part 205, Subpart B. The federal truck passby noise standard is 80 dB at 15 meters
(approximately 50 feet) from the vehicle pathway centerline. These controls are implemented
through regulatory controls on truck manufacturers.
Federal regulations for railroad noise are contained in 40 CFR, Part 201 and 49 CFR, Part 210.
Noise limits for locomotives manufactured during or after 1980 are as follows: stationary
locomotives (at idle throttle setting) are not to exceed 70 dB at 15 meters from the track
pathway centerline. Stationary locomotives (at all other throttle settings) are not to exceed
87 dB at 15 meters, and moving locomotives are not to exceed 90 dB at 15 meters. These noise
limits are implemented through regulatory controls on locomotive manufacturers.
Federal Highway Administration: In addition to noise standards for individual vehicles, under
regulations established by the U.S. Department of Transportation’s Federal Highway
Administration, noise abatement must be considered for certain federal or federally funded
projects. Abatement is an issue for new highways or significant modification of an existing
freeway. The agency must determine if the project would create a substantial increase in noise
or if the predicted noise levels approach or exceed the Noise Abatement Criteria. Under the
regulations, a substantial increase is defined as an increase in Leq of 12 dB during the peak hour
of traffic. The Noise Abatement Criteria differ among various activity categories. For noisesensitive uses – such as residences, schools, churches, parks, and playgrounds – the Noise
Abatement Criteria is Leq 57 dB (interior) and Leq 67 dB (exterior) during the peak hour of traffic
noise.
Swift Rail Development Act: The sounding of locomotive horns or whistles in advance of highway
and street at-grade crossings has been used as a safety precaution by railroads since the late
1880s. The manner in which horns have been sounded (two longs, one short, and one long) was
standardized in 1938. In response to a growing national trend towards local restrictions on the
use of locomotive horns, which caused a related increase in collisions, Congress passed the Swift
Rail Development Act, which directed the Federal Railroad Administration (FRA) to develop rules
addressing this issue. In January 2000, the FRA published a proposed rule requiring use of the
horns or whistles on approaches to every public road/rail grade crossing. An exception is made
in approved quiet zones, where supplementary safety measures have been installed or adopted
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4.6 NOISE
by the state or locality. The proposed rule would also establish an upper limit for the loudness of
train horns. Quiet zones are adopted by local governments, and then approved by the FRA.
Federal Aviation Regulations: Part 150 of the Federal Aviation Regulations addresses airport
noise compatibility planning. The regulations include a system for measuring airport noise
impacts and present guidelines for identifying incompatible land uses. All land uses are
considered compatible with noise levels of less than Ldn/CNEL 65 dB. At higher noise levels,
selected land uses are also deemed acceptable, depending on the nature of the use and the
degree of noise reduction provided by the building structure.
STATE
California Department of Transportation: The State establishes noise limits for vehicles licensed to
operate on public roads. For heavy trucks, the state passby standard is consistent with the
federal limit of 80 dB. The state passby standard for light trucks and passenger cars (less than 4.5
tons, gross vehicle rating) is also 80 dB at 15 meters from the centerline. These standards are
implemented through controls on vehicle manufacturers and by state and local laws enforced
against vehicle operators. For new roadway projects, the California Department of
Transportation (Caltrans) employs the Noise Abatement Criteria, discussed above in connection
with the Federal Highway Administration.
California Code of Regulations, California Building Code: The State has established noise
insulation standards for new multi-family residential units, hotels, and motels that would be
subject to relatively high levels of transportation-related noise. These requirements are
collectively known as the California Noise Insulation Standards, California Code of Regulations,
Title 24. The noise insulation standards set forth an interior limit of Ldn 45 dB for any habitable
room. They also require an acoustical analysis demonstrating how dwelling units have been
designed to meet this interior standard where such units are proposed in areas subject to noise
levels greater than Ldn 60 dB. If windows must be in the closed position to meet the interior noise
level standard, the project design must include a ventilation or air-conditioning system to
provide fresh air to the habitable interior environment. Title 24 standards are typically enforced
by local jurisdictions through the building permit application process.
LOCAL
General plans recognize that different types of land uses have different sensitivities toward the
surrounding noise environment. Residential areas are generally considered to be the most noisesensitive type of land use, and industrial/commercial areas are generally considered to be the
least sensitive. Local noise ordinances typically set forth standards related to construction
activities, nuisance-type noise sources (e.g., car alarms), and property line noise levels.
Existing General Plan Noise Element: The City’s 1990 General Plan Noise Element stipulates
policies for noise and land-use compatibility, exterior and interior noise level standards for noisesensitive spaces, enforcement of the City’s noise ordinance, and mitigation of new noise
sources.
Noise Ordinance: San Mateo’s noise ordinance is contained in Title 7, Section 30 of the San
Mateo Municipal Code. The noise ordinance is designed to reduce nuisance noise in the
community. The ordinance stipulates property line noise limits for various land-use types (e.g.,
residential, commercial, industrial), establishes noise limits for interior spaces at multi-family or
multi-tenant properties, and limits construction activity to designated days and times. The
ordinance also regulates amplified sound, unruly gatherings, and other nuisances.
City of San Mateo
July 2009
General Plan Update
Draft Environmental Impact Report
4.6-13
4.6 NOISE
4.6.3 IMPACTS AND MITIGATION MEASURES
STANDARDS OF SIGNIFICANCE
Implementation of the proposed General Plan would have a potentially significant noise impact
if it would result in:
•
Exposure of persons to or generation of noise levels in excess of standards established in
the local general plan or noise ordinance, or applicable standards of other agencies.
•
Exposure of persons to or generation of excessive groundborne vibration or groundborne
noise levels.
•
A substantial temporary, permanent, or periodic increase in ambient noise levels in the
project vicinity above levels existing without the project.
•
For a project located within an airport land-use plan or, where such a plan has not been
adopted, within two miles of a public airport public-use airport, expose people residing or
working in the project area to excessive noise levels.
Given that the City of San Mateo is not located within the CNEL 65 dB noise contour of San
Francisco International Airport or San Carlos Airport, no significant aircraft noise impacts are
expected. Thus, this issue is not further addressed in the EIR.
A project might have a significant effect on the environment if it will substantially increase the
ambient noise levels in the area or expose people to severe noise levels. A change in noise level
of less than 3 dB is not discernible to the general population, while an increase in transportationgenerated noise level of 3 to 5 dB is discernible to most people (California Department of
Transportation, 1991). An increase in the noise environment from transportation noise sources of 5
dB or greater is considered the minimum required increase for a change in community reaction
(U.S. Department of Transportation, 1990). Based on this and the existing Noise Element policies,
for noise-sensitive receivers, a significant increase is an increase in the existing Ldn of at least 3 dB.
Noise-sensitive receivers include residences, hotels/motels/lodging, long-term care facilities,
hospitals, schools, and multi-family common open-space areas.
Based on the City’s existing Noise Element, a project would also be considered to have a
significant impact if it generates noise levels above Ldn 60 dB at noise-sensitive receivers and
above Ldn 65 dB in commercial areas.
METHODOLOGY
This analysis evaluates the noise effects of full implementation of the proposed General Plan.
Because noise is a highly localized impact, detailed analyses are more appropriate at a project
level. Individual projects that may be proposed in the future under the new General Plan would
undergo project-level environmental review to determine whether they could generate noise
impacts specific to their site, hours of operation, and project description. These project-specific
environmental assessments would determine the magnitude of noise and vibration impacts and
potential mitigations for each project.
General Plan Update
Draft Environmental Impact Report
City of San Mateo
July 2009
4.6-14
4.6 NOISE
Transit Noise
Traffic and rail noise impacts are assessed by comparing both the existing noise levels and
standards of significance to the predicted noise levels of the proposed General Plan. Traffic
noise levels were predicted using the Federal Highway Administration’s noise prediction
algorithm. This algorithm calculates traffic noise levels based upon total traffic volumes,
percentage of medium and heavy truck traffic, and average traffic speeds. The calculated
noise levels are generally conservative, as they do not take into noise attenuation provided by
barriers or intervening buildings.
The train noise predictions were based on the Federal Transit Administration’s rail noise prediction
algorithm. This algorithm calculates Ldn noise levels based upon the number of daytime and
nighttime trains, train speed, track type, and number of cars. Again, the calculated noise levels
are conservative as they do not take into account the noise attenuation provided by barriers or
intervening buildings.
Fixed Noise Sources
There are a variety of fixed noise sources associated with implementation of the proposed
General Plan which have the potential to create noise levels in excess of City standards or result
in annoyance at existing and future noise-sensitive receivers. Some of these fixed noise sources
include mechanical equipment, industrial processes, and loading docks.
Construction Noise
Adoption of the proposed General Plan would result in development projects with associated
temporary construction noise impacts. These noise impacts would increase noise levels at
adjacent properties. In addition to typical construction activities, there is noise generated by
increased truck traffic associated with material delivery to and hauling from the construction
site. Table 4.6-3 provides typical construction noise levels. Typical hourly Leq constructiongenerated noise levels are about 81 dB to 89 dB measured at a distance of 50 feet from the
center of the site.
City of San Mateo
July 2009
General Plan Update
Draft Environmental Impact Report
4.6-15
4.6 NOISE
TABLE 4.6-3
NOISE MEASUREMENT LOCATIONS AND RESULTS
Equipment
Noise Level (dB) at 50 Feet
Earthmoving
Front Loader
79
Backhoe
85
Dozer
80
Tractor
80
Scraper
88
Grader
85
Paver
89
Materials Handling
Concrete Mixer
85
Concrete Pump
82
Crane
83
Stationary
Pump
76
Generator
78
Impact
Drilled Piles
85*
Impact Pile Driver
101
Jack Hammer
88
Pneumatic Tools
86
Other
Framing
95
Saw
78
Vibrator
76
Source: Source: U.S. Environmental Protection Agency, 1971.
* Charles M. Salter Associates Inc., Field Measurements, Kaiser Vallejo, 2005
General Plan Update
Draft Environmental Impact Report
City of San Mateo
July 2009
4.6-16
4.6 NOISE
PROJECT IMPACTS AND MITIGATION MEASURES
Traffic Noise Increase Impact
Impact 4.6.1
Increased vehicle traffic resulting from the proposed General Plan Update
land uses will result in increased ambient noise levels on local roadways. This is
a less than significant impact.
Most of San Mateo has existing noise levels that already exceed the normally acceptable levels
for “noise-sensitive” uses. Since the majority of the City is within the “conditionally acceptable”
range of between Ldn 60 dB and Ldn 70 dB, some form of noise mitigation will have to be
incorporated into building and site design for new noise-sensitive land uses. While the State
currently requires that multi-family dwellings in areas exceeding Ldn 60 dB incorporate mitigation
measures to achieve an interior sound level of Ldn 45 dB, the City of San Mateo extended this
requirement to single-family dwellings.
A few of San Mateo's residential neighborhoods that border highways and El Camino Real (SR82), are subject to sound levels exceeding Ldn 70 dB, which is in the “normally unacceptable”
range for noise-sensitive uses.
New development under the proposed General Plan Update will result in population and
employment increases, with a resultant increase in auto and truck trips. This will contribute to
increased traffic noise levels and exposure. Table 4.6-4 summarizes the Year 2030 traffic volumes
and calculated noise levels. Figure 4.6-4 illustrates the Year 2030 noise contours.
The proposed General Plan Update would result in changes of traffic noise levels ranging from a
reduction of 2.5 dB to an increase of 2.3 dB. The reduction in traffic noise along some roadway
segments is due to the construction of new sound walls and the Neighborhood Traffic
Management Program. Speeds are a factor in noise levels; however, posted speeds have not
increased along the major freeways and arterials. The presence of the rail corridor was taken
into account in both 1990 and the updated noise contours. The traffic noise level increases are
considered less than significant because the increases are less than 3 dB, which is the threshold
of significance. The electrification of the Caltrain in the future would make the Caltrain quieter;
however despite the electrification, due to the many grade crossings and stations in Sa Mateo,
the noise from the train horn dominates both existing and future contours.
The proposed General Plan Update policies would require noise studies for new noise-sensitive
developments in areas above Ldn 60 dB and implementation of noise attenuation measures as
necessary.
City of San Mateo
July 2009
General Plan Update
Draft Environmental Impact Report
4.6-17
4.6 NOISE
TABLE 4.6-4
FUTURE 2030 TRAFFIC VOLUMES AND DISTANCES TO LDN TRAFFIC NOISE CONTOURS
Street Name
Segment
Volume
Speed
Truck
(peak hour)
(mph)
Percentage
Ldn at
50
Feet
Increase in
Ldn over
Present Day
(dB)
(dB)
70 dB
60 dB
Distance, in feet, to
Ldn Noise Contours
North/South Streets
1
El Camino Real
North of 2nd Avenue
2362
35
2.00%
69.0
-0.7
43
199
2
El Camino Real
South of 2nd Avenue to 17th/Bovet
2785
35
2.00%
69.7
0.4
48
222
3
El Camino Real
South of 17th/Bovet to 28th Avenue
4257
35
2.00%
71.5
0.9
63
294
4
El Camino Real
South of 28th Avenue to Hillsdale Boulevard
2831
35
2.00%
69.8
-0.5
48
224
5
El Camino Real
South of Hillsdale Boulevard to 42nd Avenue
2533
35
2.00%
69.3
0.5
45
208
6
El Camino Real
South of 42nd Avenue
2817
35
2.00%
69.7
0.4
48
223
7
Delaware St.
North of Poplar Street
783
25
2.00%
62.2
1.0
15
70
8
Delaware St.
South of Poplar Street to 3rd Avenue
1183
25
2.00%
64.0
0.9
20
92
9
Delaware St.
South of 3rd Avenue to 9th Avenue
1478
25
2.00%
65.0
0.8
23
107
10
Delaware St.
South of 9th Avenue to 19th Avenue
1569
25
2.00%
65.2
0.9
24
112
11
Delaware St.
South of 19th Avenue to 25th Avenue
1522
25
2.00%
65.1
-0.2
24
109
12
Delaware St.
South of Saratoga Avenue
1475
25
2.00%
65.0
0.3
23
107
13
Alameda de las Pulgas
North of 20th Avenue
1700
30
2.00%
66.9
-0.1
31
145
14
Alameda de las Pulgas
South of 20th Avenue
2380
30
2.00%
68.4
0.0
39
182
15
US-101
All of San Mateo (with ten-foot tall sound walls)
18487
55
3.74%
85.1
0.2
508
2356
16
Highway 280
All of San Mateo
15804
65
1.70%
85.5
1.4
539
2503
East/West Streets
17
3rd Avenue
East of Mariners Island Boulevard
1116
30
2.00%
65.1
-0.6
24
110
18
3rd Avenue
East of Norfolk Street to Mariners Island Boulevard
2242
30
2.00%
68.1
-0.3
38
175
19
3rd Avenue
East of Humboldt Street to Norfolk Street
943
30
2.00%
64.4
-2.5
21
98
20
3rd Avenue
East of Delaware Street to Humboldt Street
1076
30
2.00%
65.0
2.3
23
107
21
3rd Avenue
East of El Camino Real to Delaware Street
879
30
2.00%
64.1
0.4
20
93
22
3rd Avenue
West of El Camino Real
927
30
2.00%
64.3
1.2
21
97
General Plan Update
Draft Environmental Impact Report
City of San Mateo
July 2009
4.6-18
4.6 NOISE
TABLE 4.6-4
FUTURE 2030 TRAFFIC VOLUMES AND DISTANCES TO LDN TRAFFIC NOISE CONTOURS (CONTINUED)
Street Name
Volume
(peak hour)
Segment
Speed
(mph)
Truck
Percentag
e
Ldn at
50
Feet
(dB)
Increase in
Ldn over
Present Day
(dB)
Distance, in feet, to
Ldn Noise Contours
70 dB
60 dB
23
4th Avenue
East of Humboldt Street
1542
30
2.00%
66.5
0.1
29
136
24
4th Avenue
East of Delaware Street to Humboldt Street
1341
30
2.00%
65.9
1.3
27
124
25
4th Avenue
East of El Camino Real to Delaware Street
1659
30
2.00%
66.8
1.3
31
143
26
4th Avenue
West of El Camino Real
919
30
2.00%
64.3
1.9
21
96
27
9th Avenue
East of Delaware Street
569
25
2.00%
60.8
0.2
12
57
28
9th Avenue
West of Delaware Street
529
25
2.00%
60.5
1.5
12
54
29
31st Avenue
West of El Camino Real
471
25
2.00%
60.0
0.2
11
50
31
42nd Avenue
West of El Camino Real
819
25
2.00%
62.4
-1.0
16
72
33
Hillsdale Blvd.
East of Norfolk Street
4481
35
2.00%
71.8
0.8
66
304
34
Hillsdale Blvd.
East of US-101 to Norfolk Street
3500
35
2.00%
70.7
1.1
56
258
35
Hillsdale Blvd.
East of Saratoga Drive to US-101
2417
35
2.00%
69.1
0.1
43
202
36
Hillsdale Blvd.
East of El Camino Real to Saratoga Drive
2599
35
2.00%
69.4
0.0
46
212
37
Hillsdale Blvd.
East of Alameda de las Pulgas to El Camino Real
2561
35
2.00%
69.3
0.4
45
210
38
Hillsdale Blvd.
East of Campus Drive to Alameda de las Pulgas
1806
35
2.00%
67.8
-0.4
36
166
39
Hillsdale Blvd.
West of Campus Drive
1329
35
2.00%
66.5
0.0
29
135
40
Peninsula Ave.
East of Delaware Street
1392
30
2.00%
66.1
0.3
27
127
41
Peninsula Ave.
West of Delaware Street
1473
30
2.00%
66.3
0.1
28
132
42
Poplar Ave.
East of Delaware Street
899
25
2.00%
62.8
0.1
17
77
43
Poplar Ave.
West of Delaware Street
1074
25
2.00%
63.6
0.7
19
87
44
Highway 92
101 to San Mateo Bridge
14136
55
4.50%
84.2
1.0
444
2062
45
Highway 92
El Camino to 101
11036
55
2.40%
82.4
1.0
335
1556
46
Highway 92
Ralston to El Camino Real
8680
55
4.55%
82.1
1.0
320
1485
47
Highway 92
280 to Ralston
10044
55
4.55%
82.8
1.0
355
1647
Source: Hexagon Transportation Consultants, 2008; Caltrans, 1998; Charles Salter Associates, 2009.
Note: Noise levels do not take into account noise attenuation provided by intervening buildings.
City of San Mateo
July 2009
General Plan Update
Draft Environmental Impact Report
4.6-19
4.6 NOISE
FIGURE 4.6-4: FUTURE 2030 NOISE CONTOURS
General Plan Update
Draft Environmental Impact Report
City of San Mateo
July 2009
4.6-20
4.6 NOISE
Proposed General Plan Policies that Reduce the Impact
Policy N 1.1:
Interior Noise Level Standard. Require submittal of an acoustical analysis and
interior noise insulation for all “noise-sensitive” land uses listed in Table 4.6-5
that have an exterior noise level above Ldn 60 dB, as shown on Figure 4.6-2.
The maximum interior noise level shall not exceed Ldn 45 dB in any habitable
rooms.
Policy N 1.2:
Exterior Noise Level Standard. Require an acoustical analysis for new parks,
play areas, and multi-family common open space (intended for the use and
the enjoyment of residents) that have an exterior noise level above Ldn 60 dB,
as shown on Figure 4.6-2. Require an acoustical analysis that uses peak-hour
Leq for new parks and play areas. Require a feasibility analysis of noise
reduction measures for public parks and play areas. Incorporate necessary
mitigation measures into residential project design to minimize common open
space noise levels. Maximum exterior noise should not exceed Ldn 67 dB for
residential uses and should not exceed Leq 65 dB during the noisiest hour for
public park uses.
The above policies that require an acoustical analysis for new noise sensitive developments and
implementation of noise attenuation measures as necessary would ensure a less than significant
impact.
Implementation of Policies N 1.1 and N 1.2: Interior and Exterior Noise Level Standards
As part of the development review process, an acoustical analysis is required for all new project
types listed in Table 4.6-5 when the site noise levels exceed the noise level standards established
in the General Plan. Mitigation measures to reduce both exterior and interior noise to
acceptable levels are required as part of the analysis, and are incorporated into the conditions
of project approval.
Lead: Planning Division reviews General Plan and consults with Building Division on scope of
analysis. Building Division approves content of final report and administers conditions of project
approval.
City of San Mateo
July 2009
General Plan Update
Draft Environmental Impact Report
4.6-21
4.6 NOISE
TABLE 4.6-5
NOISE-SENSITIVE LAND-USE COMPATIBILITY GUIDELINES FOR COMMUNITY NOISE ENVIRONMENTS
Day-Night Average Sound Level (Ldn), in dB
Normally
Acceptable2
Conditionally
Acceptable3
Normally
Unacceptable4
Single-Family Residential
50 to 59
60 to 70
Greater than 70
Multi-Family Residential
50 to 59
60 to 70
Greater than 70
Hotels, Motels, and Other
Lodging Houses
50 to 59
60 to 70
Greater than 70
Long-Term Care Facilities
50 to 59
60 to 70
Greater than 70
Hospitals
50 to 59
60 to 70
Greater than 70
Schools
50 to 59
60 to 70
Greater than 70
Multi-Family Common Open
Space Intended for the Use and
Enjoyment of Residents
50 to 67
--
Greater than 67
Land-Use Category
Noise Guidelines For Outdoor Activities
Peak Hour Leq, in dB
Land Use Category
Parks, Playgrounds
Normally
Acceptable2
Conditionally
Acceptable3
Normally
Unacceptable4
50 to 65*
--
Greater than 65*
1
These guidelines are derived from the California Department of Health Services, Guidelines for the Preparation and Content
of the Noise Element of the General Plan, 2003. The State Guidelines have been modified to reflect San Mateo's preference
for distinct noise compatibility categories and to better reflect local land-use and noise conditions. It is intended that these
guidelines be utilized to evaluate the suitability of land-use changes only and not to determine cumulative noise impacts.
Land uses other than those classified as being “noise sensitive” are exempt from these compatibility guidelines.
2
Normally Acceptable – Specified land use is satisfactory, based upon the assumption that any buildings involved are of
normal conventional construction, without any special noise insulation requirements.
3
Conditionally Acceptable – New construction should be undertaken only after a detailed analysis of the noise reduction
requirement is conducted and needed noise insulation features included in the design.
4
Normally Unacceptable – New construction should be discouraged. If new construction or development does proceed, a
detailed analysis of the noise reduction requirements must be made and needed noise insulation features included in the
design.
Source: City of San Mateo General Plan, 1990.
Policy N 2.2:
Minimize Noise Impact. Protect all “noise-sensitive” land uses listed in Table
4.6-5 from adverse impacts caused by the noise generated on site by new
developments. Incorporate necessary mitigation measures into development
design to minimize noise impacts. Prohibit long-term exposure increases in the
Ldn of 3 dB or greater at the common property line, or new uses that generate
noise levels of Ldn 60 dB or greater at the property line, excluding existing
ambient noise levels.
Policy N 2.3:
Minimize Commercial Noise. Protect land uses other than those listed as noise
sensitive” in Table 4.6-5 from adverse impacts caused by the on-site noise
generated by new developments. Incorporate necessary mitigation
measures into development design to minimize noise impacts. Prohibit new
uses that generate noise levels of Ldn 65 dB or above at the property line,
excluding existing ambient noise levels.
General Plan Update
Draft Environmental Impact Report
City of San Mateo
July 2009
4.6-22
4.6 NOISE
The above policies that require an acoustical analysis for new noise sensitive developments and
implementation of noise attenuation measures as necessary would ensure a less than significant
impact.
Implementation of Policies N 2.2 and N2.3: Minimize Noise
Where the potential exists for noise impacts inconsistent with these policies, a noise report
identifying noise impacts and mitigation measures is required as part of the development review
process. Mitigation measures are then incorporated as conditions of the project approval.
Lead: Planning Division reviews the General Plan and consults with the Building Division on the
scope of the analysis. The Building Division approves the content of the final report and
administers the conditions of project approval.
Policy N 2.4:
Traffic Noise. Recognize projected increases in ambient noise levels resulting
from traffic increases, as shown on Figure 4.6-4. Promote the installation of
noise barriers along highways where “noise-sensitive” land uses listed in Table
4.6-5 are adversely impacted by unacceptable noise levels (Ldn 60 dB or
above). Require adequate noise mitigation to be incorporated into the
widening of SR-92 and US-101. Accept noise increases on El Camino Real at
existing development, and require new multi-family development to provide
common open space having a maximum exterior noise level of Ldn 67 dB.
The above policies that require an acoustical analysis for new noise sensitive developments and
implementation of noise attenuation measures as necessary would ensure a less than significant
impact.
Implementation N 2.4: Traffic Noise
Sound walls have been constructed along US-101. Preliminary design work has not yet started on
the widening of SR-92; however, the issue of sound walls will be addressed during both the
design and environmental review phases of the project. Noise standards for development along
El Camino Real are imposed on a case-by-case basis consistent with this policy's guidelines. New
multi-family developments are required to comply with exterior noise standards as part of the
development review process for consistency with the State Building Code.
Lead: The Public Works Department coordinates sound wall construction with Caltrans. Planning
and Building Divisions coordinate the review and application of conditions of approval for new
development regarding compliance with this policy.
Mitigation Measures
None required.
Rail Noise Increase Impact
Impact 4.6.2
Increased number of daily trains, from 98 per day to 110 per day, will result in
increased ambient noise levels for adjacent receivers during the
implementation of the General Plan Update. This is a less than significant
impact.
City of San Mateo
July 2009
General Plan Update
Draft Environmental Impact Report
4.6-23
4.6 NOISE
A significant component of the noise produced by Caltrain is from the warning horns blown at
at-grade crossings and when approaching stations. As there are numerous at-grade crossings
and three stations in San Mateo, the use of train horns is frequent. The Joint Powers Authority,
which oversees Caltrain operations, expects the number of trains to increase from 98 per day to
110 per day by the Year 2014 (Caltrain Short Range Transit Plan, 2008). This would result in an
increase in noise level of less than 1 dB, which is considered less than significant.
A few of San Mateo's residential neighborhoods that border the railway line are subject to sound
levels exceeding Ldn 70 dB, which is in the “normally unacceptable” range for “noise-sensitive”
uses. Significant reductions in noise would be achieved as grade crossings are eliminated, since
train operators would no longer sound the train’s horn. Currently, there is no schedule for the
elimination of at-grade crossings; however, the electrification of the Caltrain system and the
proposed high-speed rail system will likely necessitate the removal of the at-grade crossings.
Proposed General Plan Policy that Reduces the Impact
Policy N 2.5:
Railroad Noise. Promote the installation of noise barriers along the railroad
corridor where “noise-sensitive” land uses are adversely impacted by
unacceptable noise levels (Ldn 60 dB or greater). Promote adequate noise
mitigation to be incorporated into any rail service expansion or track
realignment. Study the need of depressing the rail line to eliminate at-grade
crossings or other mitigation measures to decrease noise levels prior to
substantial expansion of the rail service.
Implementation Policy N 2.5: Railroad Noise
The Joint Powers Authority has completed a study of electrification of the rail lines, and has
adopted a policy for its implementation. Electrification of the rail line, in conjunction with the
elimination of at-grade crossings, would greatly reduce railroad noise impacts. Installation of
noise barriers is analyzed on a project-by-project basis for development adjacent to the railroad.
Noise impacts were also considered in the examination of alignment alternatives in the railroad
corridor study.
Lead: The Public Works Department coordinates with the Joint Powers Authority on railroad
alignment. The Planning and Building Divisions coordinate the review and application of
conditions of approval for new development adjacent to the rail corridor regarding noise
impacts.
Mitigation Measures
None required.
Fixed and Other Noise Source Impacts
Impact 4.6.3
Fixed noise sources (e.g., mechanical equipment) and temporary noise
sources such as construction activity and landscaping can cause temporary
or periodic increases in noise in excess of City standards as part of
implementation of the proposed General Plan Update. In addition, new
noise-sensitive land uses could be located adjacent to existing fixed noise
sources. This is a less than significant impact.
General Plan Update
Draft Environmental Impact Report
City of San Mateo
July 2009
4.6-24
4.6 NOISE
Implementation of the proposed General Plan Update could result in the future development of
land uses with mechanical equipment (e.g., rooftop HVAC units, trash compactors, car wash
equipment) that exceed the City’s noise standards. Also, new noise-sensitive land uses might be
located adjacent to existing fixed noise sources.
Construction activities and landscaping activities can cause significant temporary or periodic
increases in noise with the potential for annoyance.
Proposed General Plan Policy that Reduces the Impact
Policy N 2.1:
Noise Ordinance. Continue implementation and enforcement of the City's
existing noise control ordinance: a) which prohibits noise that is annoying or
injurious to neighbors of normal sensitivity, making such activity a public
nuisance, and b) restricts the hours of construction to minimize noise impact.
Implementation of N 2.1: Noise Ordinance
Noise nuisances, as defined in the City's Municipal Code, are abated through a standardized
enforcement process, which includes referral to the Housing and Advisory Appeals Board. This
includes noise generated by building construction and equipment at unauthorized times.
Lead: Code Enforcement Division
Mitigation Measures
None required.
4.6.4 CUMULATIVE SETTING, IMPACTS AND MITIGATION MEASURES
CUMULATIVE SETTING
The City of San Mateo is located within San Mateo County, south of San Francisco and north of
San Jose. The projects summarized in Table 4.0-2, along with projects planned in nearby
communities (e.g., Burlingame, Belmont, Millbrae, San Bruno, Redwood City, San Carlos) may,
cumulatively, cause a significant noise impact in the City of San Mateo.
The following impact analysis was performed to determine the cumulative impact of the
proposed General Plan Update, projects associated with the proposed General Plan Update,
and projects planned in nearby communities. Fixed and other local noise source impacts are
site-specific and are not considered a cumulative impact.
CUMULATIVE IMPACTS AND MITIGATION MEASURES
Cumulative Traffic Noise Impact
Impact 4.6.4
Increased vehicle traffic resulting from the proposed General Plan Update
land uses along with development in adjacent communities will result in
increased ambient noise levels on local roadways. This impact is considered
less than cumulatively considerable.
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4.6 NOISE
Implementation of the proposed General Plan Update and development in adjoining
communities will increase traffic volumes, with resultant traffic noise increases, in the City of San
Mateo. Table 4.6-4 shows the expected future traffic volumes on major roads and provides the
expected noise increases for roads with increasing traffic volumes. The traffic volumes used to
calculate the noise increase take into account both proposed development in the City of San
Mateo and proposed development in nearby cities. Since traffic noise increases will be less than
3 dB, the cumulative noise increases are considered less than significant.
Proposed General Plan Policies that Reduce the Impact
Policy N 1.1:
Interior Noise Level Standard. Require submittal of an acoustical analysis and
interior noise insulation for all “noise-sensitive” land uses listed in Table 4.6-5
that have an exterior noise level above Ldn 60 dB, as shown on Figure 4.6-2.
The maximum interior noise level shall not exceed Ldn 45 dB in any habitable
rooms.
Policy N 1.2:
Exterior Noise Level Standard. Require an acoustical analysis for new parks,
play areas, and multi-family common open space (intended for the use and
the enjoyment of residents) that have an exterior noise level above Ldn 60 dB,
as shown on Figure 4.6-2. Require an acoustical analysis that uses peak-hour
Leq for new parks and play areas. Require a feasibility analysis of noise
reduction measures for public parks and play areas. Incorporate necessary
mitigation measures into residential project design to minimize common open
space noise levels. Maximum exterior noise should not exceed Ldn 67 dB for
residential uses and should not exceed Leq 65 dB during the noisiest hour for
public park uses.
The above policies that require an acoustical analysis for new noise sensitive developments and
implementation of noise attenuation measures as necessary would ensure a less than significant
impact
Implementation of Policies N 1.1 and N 1.2: Interior and Exterior Noise Level Standards
As part of the development review process, an acoustical analysis is required for all new project
types listed in Table 4.6-5 when the site noise levels exceed the noise level standards established
in the General Plan. Mitigation measures to reduce both exterior and interior noise to
acceptable levels are required as part of the analysis and are incorporated into the conditions
of project approval.
Lead: Planning Division reviews General Plan and consults with Building Division on scope of
analysis. Building Division approves content of final report and administers conditions of project
approval.
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July 2009
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4.6 NOISE
TABLE 4.6-5
NOISE-SENSITIVE LAND USE COMPATIBILITY GUIDELINES FOR COMMUNITY NOISE ENVIRONMENTS
Day-Night Average Sound Level (Ldn), in dB
Normally
Acceptable2
Conditionally
Acceptable3
Normally
Unacceptable4
Single-Family Residential
50 to 59
60 to 70
Greater than 70
Multi-Family Residential
50 to 59
60 to 70
Greater than 70
Hotels, Motels, and Other
Lodging Houses
50 to 59
60 to 70
Greater than 70
Long-Term Care Facilities
50 to 59
60 to 70
Greater than 70
Hospitals
50 to 59
60 to 70
Greater than 70
Schools
50 to 59
60 to 70
Greater than 70
Multi-Family Common Open
Space Intended for the Use and
Enjoyment of Residents
50 to 67
--
Greater than 67
Parks, Playgrounds
50 to 65*
--
Greater than 65*
Land-Use Category
1
These guidelines are derived from the California Department of Health Services, Guidelines for the Preparation and Content
of the Noise Element of the General Plan, 2003. The State Guidelines have been modified to reflect San Mateo's preference
for distinct noise compatibility categories and to better reflect local land-use and noise conditions. It is intended that these
guidelines be utilized to evaluate the suitability of land-use changes only and not to determine cumulative noise impacts.
Land uses other than those classified as being “noise sensitive” are exempt from these compatibility guidelines.
2
Normally Acceptable – Specified land use is satisfactory, based upon the assumption that any buildings involved are of
normal conventional construction, without any special noise insulation requirements.
3
Conditionally Acceptable – New construction should be undertaken only after a detailed analysis of the noise reduction
requirement is conducted and needed noise insulation features included in the design.
4
Normally Unacceptable – New construction should be discouraged. If new construction or development does proceed, a
detailed analysis of the noise reduction requirements must be made and needed noise insulation features included in the
design.
Source: City of San Mateo General Plan, 1990
Policy N 2.2:
Minimize Noise Impact. Protect all “noise-sensitive” land uses listed in Table
4.6-5 from adverse impacts caused by the noise generated on site by new
developments. Incorporate necessary mitigation measures into development
design to minimize noise impacts. Prohibit long-term exposure increases in the
Ldn of 3 dB or greater at the common property line, or new uses that generate
noise levels of Ldn 60 dB or greater at the property line, excluding existing
ambient noise levels.
Policy N 2.3:
Minimize Commercial Noise. Protect land uses other than those listed as noise
sensitive” in Table 4.6-5 from adverse impacts caused by the on-site noise
generated by new developments. Incorporate necessary mitigation
measures into development design to minimize noise impacts. Prohibit new
uses that generate noise levels of Ldn 65 dB or above at the property line,
excluding existing ambient noise levels.
The above policies that require an acoustical analysis for new noise sensitive developments and
implementation of noise attenuation measures as necessary would ensure a less than significant
impact.
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4.6 NOISE
Implementation of Policies N 2.2 and N2.3: Minimize Noise
Where the potential exists for noise impacts inconsistent with these policies, a noise report
identifying noise impacts and mitigation measures is required as part of the development review
process. Mitigation measures are then incorporated as conditions of the project approval.
Lead: Planning Division reviews the General Plan and consults with the Building Division on the
scope of the analysis. The Building Division approves the content of the final report and
administers the conditions of project approval.
Policy N 2.4:
Traffic Noise. Recognize projected increases in ambient noise levels resulting
from traffic increases, as shown on Figure 4.6-4. Promote the installation of
noise barriers along highways where “noise-sensitive” land uses listed in Table
4.6-5 are adversely impacted by unacceptable noise levels (Ldn 60 dB or
above). Require adequate noise mitigation to be incorporated into the
widening of SR-92 and US-101. Accept noise increases on El Camino Real at
existing development, and require new multi-family development to provide
common open space having a maximum exterior noise level of Ldn 67 dB.
The above policies that require an acoustical analysis for new noise sensitive developments and
implementation of noise attenuation measures as necessary would ensure a less than significant
impact.
Implementation N 2.4: Traffic Noise
Sound walls have been constructed along US-101. Preliminary design work has not yet started on
the widening of SR-92; however, the issue of sound walls will be addressed during both the
design and environmental review phases of the project. Noise standards for development along
El Camino Real are imposed on a case-by-case basis consistent with this policy's guidelines. New
multi-family developments are required to comply with exterior noise standards as part of the
development review process for consistency with the State Building Code.
Lead: The Public Works Department coordinates sound wall construction with Caltrans. Planning
and Building Divisions coordinate the review and application of conditions of approval for new
development regarding compliance with this policy.
Mitigation Measures
None required.
Cumulative Rail Noise Impact
Development in surrounding communities is not expected to increase rail traffic along the
Caltrain/Southern Pacific rail line over that discussed in Section 4.6.2 above. No additional
analysis is necessary.
Fixed and Other Noise Sources
Fixed and other local noise source impacts are site-specific and are not considered a
cumulative impact. No additional analysis is necessary.
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July 2009
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4.6 NOISE
FIFTH AVENUE RECLASSIFICATION
Charles M. Salter Associates Inc., provided additional information and analysis related to the
redesignation of Fifth Avenue to a collector street. While the impact analysis is detailed in the
Traffic and Circulation section of the EIR, a summary of the findings of the noise and vibration
analysis is provided below:
Based on the traffic volumes provided by Hexagon Transportation Consultants (found in the
Traffic and Circulation section of the DEIR) the future condition assumes that there will be an
increase in truck volume due to the proposed reclassification of Fifth Avenue. The noise from
additional trucks using Fifth Avenue will increase the noise levels at the adjacent residence by
up to 1 dB; however, this increase is not considered significant.
The Technical Noise Supplement dated October 1998, published by the California Department
of Transportation states, “It is widely accepted that the average healthy ear, however, can
barely perceive noise level changes of 3 dBA.”
Table 4.6-6 below summarizes the traffic data and the expected increase in noise levels of 1dB
along Fifth Avenue. The City’s General Plan considers increases of less than Ldn 3 dB to not be
significant.
TABLE 4.6-6
TRAFFIC VOLUMES AND NOISE LEVEL INCREASE
Average Daily
Car Volume
Average Daily
Truck Volume
Truck
Percentage
Fifth Avenue,
between Humboldt Street
and Idaho Street
Present – 1314
Present – 74
Present – 5%
Future – 1314
Future – 280
Future – 18%
Fifth Avenue,
between Idaho Street and
Amphlett Boulevard
Present – 1314
Present – 74
Present – 5%
Future – 1314
Future – 280
Future – 18%
Segment
Change in
Existing Future
Noise
Ldn
Ldn
Level (dB)
(dB)
(dB)
(dB)
Significant
Increase?
(>3 dB)
64
65
+1
No
68
68
-
No
According to the Federal Transit Administration, a vibration level of 65 VdB is considered to be
the threshold of human perception, while 72 VdB is considered the threshold for residential
annoyance from “frequent” events (i.e., more than 70 events per day).
Existing vibration levels for six truck passbys varied from 52 VdB to 59 VdB. These measured
vibration levels are below the level of human perception. Since truck passbys are not
perceptible to occupants in the residences, additional truck traffic will not create a vibration
impact.
Bumps and pavement irregularities were observed along Fifth Avenue. These bumps and
irregularities can increase noise and vibration levels during truck passbys. The scheduled overlay
to Fifth Avenue will mitigate these bumps and irregularities, and the noise and vibration levels
should decrease.
Vibration levels from truck passbys are below the level of human perception; additional truck
traffic would continue to be below the level of perception and therefore would not be a
vibration impact.
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July 2009
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4.6 NOISE
REFERENCES
California Department of Transportation (Caltrans). 1998. A Technical Supplement to the Traffic
Noise Analysis Protocol.
Charles M. Salter Associates. 2005. Measurements of Pile Driving at Kaiser Vallejo.
Charles M. Salter Associates. 2008. Environmental Noise Measurements Conducted at Ten
Locations in San Mateo.
Charles M. Salter Associates. 2009. Fifth Avenue Reclassification Noise and Vibration Study.
City of San Mateo. 1990. City of San Mateo General Plan.
City of San Mateo. 2004. City of San Mateo Municipal Code. San Mateo, CA.
Federal Highway Administration. 1977. Highway Traffic Noise Prediction Model FHWA-RD-77-108.
Hexagon Transportation Consultants. 2008. Present (2005) and Future (2030) Traffic Volumes
provided via email from Jill Hough.
Peninsula Corridor Joint Powers Board. 2008. Caltrain Short Range Transit Plan.
United States Department of Transportation. 1990. Urban Mass Transportation Administration,
Guidance Manual for Transportation Noise and Vibration Impact Assessment.
United States Environmental Protection Agency (USEPA). 1971. Noise from Construction
Equipment and Operations, Building Equipment and Home Appliances.
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July 2009
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