4.10 NOISE AND VIBRATION

Redwood City New General Plan 4.10 Noise and Vibration

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4.10 NOISE AND VIBRATION This section describes the existing noise environment within the plan area and the potential noise impacts that could occur with the adoption of the New General Plan. Information in this section was derived from studies conducted by Illingworth & Rodkin, Inc.

4.10.1 NOISE MEASUREMENT UNITS Noise is usually defined as any “unwanted sound,” and consists of sounds that may produce physiological or psychological damage and/or interfere with communication, work, rest, recreation, and sleep.

The decibel (dB) is a logarithmic unit of measurement indicating the relative amplitude of a sound. Because decibels are logarithmic units, sound pressure levels cannot be added or subtracted by ordinary arithmetic means. For example, if one automobile produces a sound pressure level of 70 dB when it passes an observer, two cars passing simultaneously would not produce 140 dB; they would, in fact, combine to produce 73 dB. When two sounds of equal sound pressure levels are combined, they will produce a combined sound pressure level that is 3 dB greater than the original sound pressure level. Therefore, sound energy must be doubled to produce a 3 dB increase.

The decibel alone is not a reliable indicator of loudness of a sound because the human ear does not respond uniformly to sounds at all frequencies. For example, the human ear is less sensitive to low and high frequencies than to medium frequencies that more closely correspond with human speech. In response to the human ear sensitivity, the A-weighted noise level, referenced in units of dBA, was developed to better correspond with people’s subjective judgment of sound levels. In general, when similar sounds are combined, the human ear does not typically notice changes in a noise level of less than 3 dBA.1 Some individuals notice changes in level from 3 to 5 dBA. An increase of greater than 5 dBA is readily noticeable to most people, while the human ear perceives a 10 dBA increase in sound level to be a doubling of sound.

Table 4.10-1 shows representative outdoor and indoor sound levels in units of dBA.

Sensitivity to noise increases at night, as the background noise levels are typically limited and the overall ambient noise levels are usually lower than the levels during the day. The Community Noise Equivalent Level (CNEL) is the average noise level during a 24-hour day, weighted to take into account that individuals are usually more sensitive to noise in late evening and early morning hours. CNEL adds 5 dB to noises measured from 7:00 p.m. to 10:00 p.m., and 10 dB to sound levels measured between 10:00 p.m. and 7:00 a.m.

Table 4.10-2 lists and defines other acoustical terminology.

1 USDOT, 1995.


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Table 4.10-1 Common Sound Levels and their Noise Sources

Noise Source

A-Weighted Sound Decibels Noise Environment

Subjective Evaluations

Human Breathing 0 Very Faint

Rustling Leaves 20 Very Faint

Soft Whisper 30 Faint

Average Residence Without Stereo Playing 40 Faint

Large Transformer 45 Quiet

Light Traffic; Soft Radio Music in Apartment 50 Quiet ¼ as loud

Suburban Street 55 Moderate

Average Office 60 Moderate ½ as loud

Near Freeway Auto Traffic 70 Moderately Loud

Busy Restaurant 75 Moderately Loud

Pneumatic Drill; Vacuum Cleaner 80 Moderately Loud 2 times as loud

Freight Cars; Living Room Music 85 Moderately Loud

Garbage Disposal 90 Very Loud 4 times as loud

Ambulance Siren; Food Blender 95 Very Loud

Pile Driver; Noise Urban Street/ Heavy City Traffic 100 Very Loud 8 times as loud

Accelerating Motorcycle at a few feet away 110 Very Loud 16 times as loud

Hard Rock Band 120 Threshold of Feeling 32 times as loud

Civil Defense Siren 130 Threshold of Pain 64 times as loud

Jet Engine in close proximity 140 Deafening 128 times as loud

Source: Illingworth & Rodkin, 2008.


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Table 4.10-2 Definitions of Acoustical Terms

Acoustical Term Definition

Decibel, dB A unit describing the amplitude of sound, equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound measured to the reference pressure, which is 20 micropascals (20 micronewtons per square meter).

Frequency, HZ The number of complete pressure fluctuations per second above and below atmospheric pressure.

A-Weighted Sound Level, dBA The sound pressure level in decibels as measured on a sound level meter using the A-weighting filter network. The A-weighting filter de-emphasizes the very low and very high frequency components of the sound in a manner similar to the frequency response of the human ear, and correlates well with subjective reactions to noise. All sound levels in this report are dBA, unless reported otherwise.

L01, L10, L50, L90 The dBA noise levels that are exceeded 1%, 10%, 50%, and 90% of the time during the measurement period.

Equivalent Continuous Noise Level, Leq The average dBA noise level during the measurement period.

Community Noise Equivalent Level, CNEL The average dBA noise level during a 24-hour day, obtained after the addition of 5 decibels in the evening from 7:00 p.m. to 10:00 p.m., and after the addition of 10 decibels to sound levels measured in the night between 10:00 p.m. and 7:00 a.m.

Day/Night Noise Level, Ldn The average dBA noise level during a 24-hour day, obtained after addition of 10 decibels to levels measured in the night between 10:00 p.m. and 7:00 a.m.

Lmax, Lmin The maximum and minimum dBA noise level during the measurement period.

Ambient Noise Level The composite of noise from all sources near and far. The normal or existing level of environmental noise at a given location.

Intrusive That noise that intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends on its amplitude, duration, frequency, and time of occurrence, and tonal or informational content as well as the prevailing ambient noise level.


Groundborne Vibration Fundamentals Railroad trains within the plan area are potential sources of substantial ground vibration depending on the distance, the type and the speed of trains, and the type of railroad track. People’s response to ground vibration has been correlated best with the vibration velocity level. The vibration velocity level is expressed on the decibel scale. The abbreviation “VdB” is used in this document for vibration decibels to reduce the potential for confusion with sound decibels.


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Typical background vibration levels in residential areas are usually 50 VdB or lower, well below the threshold of perception for most humans. Perceptible vibration levels inside residences are attributed to the operation of heating and air conditioning systems, door slams, and foot traffic. Construction activities, train operations, and street traffic are some of the most common external sources of vibration that can be perceptible inside residences. Table 4.10-3 identifies some common sources of vibration and the association to human perception or the potential for structural damage.

Table 4.10-3 Typical Levels of Groundborne Vibration

Human/Structural Response Velocity Level, VdB Typical Events

(50-foot setback)

Threshold, minor cosmetic damage 100 Blasting, pile driving, vibratory

compaction equipment

Heavy tracked vehicles (Bulldozers, cranes, drill rigs)

Difficulty with tasks such as reading a video or computer screen

90 Commuter rail, upper range

Residential annoyance, infrequent events 80 Rapid transit, upper range

Residential annoyance, occasional events 80

Commuter rail, typical Bus or truck over bump or on rough roads

Residential annoyance, frequent events 70 Rapid transit, typical

Approximate human threshold of perception to vibration 70 Buses, trucks and heavy street

traffic

60 Background vibration in residential settings in the absence of activity

Lower limit for equipment ultra-sensitive to vibration 50

Background vibration in residential settings in the absence of activity


4.10.2 ENVIRONMENTAL SETTING

Existing Noise Conditions Ground transportation, which includes vehicular traffic and railroad trains, is the dominant source of noise and vibration within the plan area. Local traffic is the most significant source of community noise in the plan area because it occurs everywhere and the sources are in close proximity to the sensitive receptors (i.e., residences, schools, hospitals and parks). Freeway noise can affect larger geographical areas because of the high volumes of traffic and high speeds. Railroad trains are the source of the highest regularly occurring instantaneous maximum noise and vibration levels in the


M a y 2 0 1 0 D r a f t E I R 4.10-5

community. Aircraft operations in the vicinity of the San Carlos Airport are also a source of noise within the plan area.

Other noise and vibration sources such as industry, mechanical equipment on buildings, and recreational activities contribute, although to a lesser degree, at particular locations throughout the plan area.

A comprehensive noise monitoring survey was conducted in July 2008 in anticipation of the New General Plan. The City selected noise measurement locations to provide information on the distribution of noise levels along the streets and highways, and to determine the level of baseline ambient noise levels in residential neighborhoods. Noise measurement locations were also selected to measure noise levels generated by railroad trains, and stationary sources including industrial and commercial businesses.

Based on familiarity gained through numerous noise studies previously prepared for the City, a review of aerial photos, and discussions with City staff, 11 long-term noise measurement sites and 14 short-term noise measurement sites were identified for the noise analysis. Figure 4.10-1 shows the noise measurement locations.

Long-term noise sampling consisted of hourly noise measurements over a period of 48 hours. Short-term sampling consisted of noise measurements every minute over a period of 10 minutes. Long term measurements provided the hourly distribution of noise levels and the CNEL. Short term measurements with concurrent traffic counts were used to calibrate the traffic noise model; Figure 4.10-2 shows noise exposure contours developed from this information for the entire plan area.

Previous noise study reports were reviewed for recent projects (labeled in red in Figure 4.10-1) where noise data, collected since 2005, were utilized in reconnaissance for the New General Plan. Table 4.10-4 summarizes the long-term noise measurement results. Table 4.10-5 summarizes the short-term noise measurement results. Existing noise conditions in the plan area are further discussed below. A full discussion of the daily trend in noise levels for the long-term noise measurements is included in Appendix H.

Freeways and Expressways

U.S. 101, Interstate 280 (I-280), El Camino Real (State Route 82), and Woodside Road (State Route 84) are the major north-south transportation corridors transecting the plan area.

As shown in Figure 4.10-1, noise measurements were made adjacent to U.S. 101 at sites LT-2, LT-3, and ST-1. Existing noise levels adjacent to the highway are approximately 67-76 dBA CNEL. Highway traffic noise levels vary dramatically depending on the proximity of the receiver to the highway and presence or lack of shielding. Noise measurement LT-8 was made adjacent to I-280. Noise levels along the I-280 corridor are approximately 62-64 dBA CNEL. Noise measurement LT-7 was located on the west side of Woodside Road. The average noise level at this location was calculated to be 67-70 dBA CNEL. Noise measurement site LT-11 was made along El Camino Real, south of Woodside Road, where noise levels were approximately 70-73 dBA CNEL.


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Table 4.10-4 Long-Term Noise Measurement Results

Receiver ID

AM/PM Measurement Location, Date Measured Noise Levels, dBA Calculated CNEL, dBA

Primary Noise Source

Leq L10 L50 L90

LT-1 AM About 25 feet from the Centerline of Redwood Shores Parkway (07/10/08-07/14/08)

56-78 65-89 46-60 39-53 62 - 67 Redwood Shores

Parkway PM 47-61 47-64 41-51 39-47

LT-2 AM At 1399 Shoreway Road - 150 feet from the edge of U.S. 101 (07/10/08-07/14/08).

65-76 67-75 64-73 62-71 74-76 U.S. 101

PM 61-72 65-74 60-72 54-70

LT-3 AM In the parking lot of mobile homes at 3015 East Bayshore Road - 100 feet from the edge of U.S. 101 (07/10/08-07/14/08).

59-72 61-73 57-67 54-62 67-72 U.S. 101

PM 54-72 56-73 51-66 45-63

LT-4 AM In the parking lot of Seaport Center (07/16/08-07/18/08) 53-65 55-67 52-64 50-61 62 Seaport Boulevard

PM 49-60 50-61 47-60 45-58

LT-5 AM Fair Oaks Avenue between 7th Avenue and 8th Avenue, across from Caltrain Station (07/16/08-07/18/08)

54-66 54-66 46-58 44-55 61 Caltrain/Fair Oaks

Avenue PM 41-63 39-61 38-46 36-43

LT-6 AM On Glendale Avenue between Amherst Avenue and 5th Avenue, across from Caltrain Station (07/16/08-07/18/08)

59-71 51-61 48-58 45-55 69-70 Caltrain/distant

traffic PM 40-68 41-54 36-48 35-44

LT-7 AM 30 feet from the center of Woodside Road (07/18/2008-07/22/2008)

61-72 65-73 56-69 43-64 67-70 Woodside Road

PM 50-67 46-70 34-63 32-51

LT-8 AM 45 feet from the center of Farm Hill Boulevard (07/18/08-07/22/08)

56-66 59-69 39-64 32-56 62-64

Farm Hill Boulevard/distant traffic PM 42-60 26-65 24-53 23-43

LT-9 AM 20 feet from the center of Alameda de las Pulgas – 30 feet from the edge of James Avenue (07/23/08-07/28/08)

57-66 59-70 41-64 38-52 64-66 Alameda de las

Pulgas PM 43-61 37-65 36-51 36-43

LT-10 AM Front of 1503 Whipple Avenue, about 25 feet from the center of the road (07/23/08-07/28/08)

62-71 67-72 50-68 41-61 68-70 Whipple Avenue

PM 52-66 41-70 30-60 28-48

LT-11 AM 25 feet from the center of El Camino Real, South of Woodside Boulevard (07/23/08-07/28/08)

64-75 68-77 59-69 49-62 70-73 El Camino Real

PM 55-69 57-72 44-63 41-56

Note: AM = 7:00 a.m.-10:00 p.m.; PM = 10:00 p.m. to 7:00 a.m. Source: Illingworth & Rodkin, 2008.


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Table 4.10-5 Short-term Noise Measurement Locations

Receiver ID

Date (Time)

Measurement Location, Date Measured Noise Levels, dBA

Calculated CNEL, dBA

Primary Noise Source

Leq L10 L50 L90

ST-1 07/10/08 (2:56 to 3:06 p.m.)

In front of 3232 Rolison Road - 15 feet from the center of the road 68 71 64 62 70 U.S. 101/Rolison Road

ST-2 07/10/08 (3:28 to 3:38 p.m.)

On Bridge Parkway - 75 feet from the center of Redwood Shores Parkway 62 64 57 51 66 Redwood Shores Parkway

ST-3 07/10/08 (4:00 to 4:10 p.m.)

About 25 feet from the center of Marine Parkway - 200 feet from the edge of Shell Parkway 56 60 52 47 60 Marine Parkway

ST-4 07/15/08 (2:06 to 2:16 p.m.)

Fair Oaks Avenue - 15 feet from the center of the road 58 62 53 50 63 Fair Oaks Avenue

ST-5 07/15/08 (2:27 to 2:37 p.m.)

About 20 feet from the center of Marsh Avenue - 100 feet from the edge of Florence Street 72 75 69 60 76 Marsh Avenue

ST-6 07/15/08 (3:42 to 3:52 p.m.)

About 25 feet from the center of Middlefield Road 72 75 67 62 75 Woodside Road / Middlefield Road

ST-7 07/18/08 (11:03 to 11:13 a.m.)

About 30 feet from the center of Seaport Boulevard 71 75 65 57 75 Trucks along portion of Seaport Boulevard

ST-8 07/18/08 (1:34 to 1:44 p.m.)

About 20 feet from the center of Farm Hill Road near McGarvey Avenue 62 67 57 44 58 Farm Hill Road

ST-9 07/18/08 (2:05 to 2:15 p.m.)

On Santa Clara Avenue near Idyllwild Drive 61 63 46 40 61 Santa Clara Avenue

ST-10 07/23/08 (11:36 to 11:46 a.m.)

About 2,000 feet from I-280, on Woodside Way near Glencrag Way 49 47 43 41 49 Distant traffic

ST-11 07/28/08 (10:32 to 10:42 a.m.)

25 feet from the center of El Camino Real near Claremont Street 69 72 66 62 68 El Camino Real

ST-12 07/28/08 (10:59 to 11:09 a.m.)

Off Brewster Street - 25 feet from the center of the road, near King Street 60 64 53 44 60 Brewster Street

ST-13 07/28/08 (11:18 to 11:28 a.m.)

Hudson Street between Jefferson Avenue and Madison Avenue 63 68 55 46 63 Hudson Street

ST-14 07/28/08 (11:38 to 11:48 a.m.)

15 feet from the center of Valota Avenue between Redwood Avenue and Oak Avenue 59 63 54 46 60 Hudson Street

Source: Illingworth & Rodkin, 2008

Redwood City General Plan EIR FIG 4.10-1Noise Receiver Locations

Geografika Consulting 07.01.09

LegendShort-term Measurement ReceiverLong-term Measurement ReceiverExisting Noise Data Location


NORTH

0 3,000 6,000Feet

1 inch equals 6,000 feet

NOTE: Calculations assume an acoustically hard ground surfaceand do not take shielding from structures or barriers into account.Railroad noise levels are substantially higher near at-gradecrossings as a result of train warning whistles.

Redwood City General Plan EIR FI

G 4.10-2Existing Noise Contours in Plan Areafor Major Roadways and Railroads


Legend


NORTH

SCALE


CNEL Noise Levelin dB(A)

< = 5555 < < = 6060 <65 <70 <75 <

< = 65< = 70< = 75

0 1250 2500 5000Feet


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Local Arterial Roadways

Whipple Avenue, Alameda de las Pulgas, Jefferson Avenue, Redwood Shores Parkway, Marine Parkway, Farm Hill Boulevard, Middlefield Road, Broadway, Veterans Boulevard, and Seaport Boulevard are some of the major local arterial roadways in the plan area. Measurements at sites LT-1, LT-9, and LT-10 indicate that existing noise levels in residential areas near these major arterial roadways typically range from about 60-70 dBA CNEL.

Railroads

Railroads are a significant source of transportation-related noise and vibration in the plan area. Noise measurements made at sites LT-5 and LT-6 provided the daily average noise levels and the instantaneous maximum noise levels resulting from train passbys, near grade crossings where railroad train horns are normally sounded, and away from grade crossings. Average daily noise levels along the railroad lines ranged from 61-70 dBA CNEL. Maximum noise levels from train passbys ranged from 85 to 95 dBA at 40 feet from site LT-6. Near at-grade crossings, where train-warning whistles are sounded to warn pedestrians and motorists of oncoming trains, maximum noise levels range from about 90 to 100 dBA at 40 feet from the tracks.

Groundborne vibration occurs in areas adjacent to fixed rail lines when railroad trains pass through the plan area. Vibration levels along the railroad corridors are proportional to the speed and weight of the trains as well as the condition of the tracks and train engine and car wheels. Typically, the setback to the 72 VdB contour along the Caltrain tracks is 100 feet or less from the center of the near track. Recent vibration measurements conducted within the vicinity of the plan area indicate that the 72 VdB contour distances were about 65 feet from the center of the railroad tracks for the maximum measured train vibration level and about 55 feet from the center of the railroad tracks for typical train passbys. As train activity in the plan area is similar to the surrounding areas, it is anticipated that vibration levels would be the same.

Aircraft

Aircraft operations in the vicinity of the San Carlos Airport are also a source of noise within the plan area. Noise measurements were attempted in the vicinity of the airport during the noise monitoring survey, but were not completed at the request of airport security officials. Noise data contained in the 1996 San Mateo County Comprehensive Airport Land Use Plan (CLUP) were then reviewed to identify areas where aircraft noise levels would exceed those considered compatible with noise-sensitive development. Figure 4.10-3 shows projected 1995 noise contours for the airport.

An Aviation Easement Review Area is established in the CLUP identifying the geographic area where aircraft noise exceeds 55 dBA CNEL. The Airport Land Use Commission (ALUC) requests that local agencies grant an aviation easement to the County of San Mateo when new, potentially sensitive developments are proposed for the area within the airport’s 55 dBA CNEL noise contour.

Redwood City General Plan EIR FIG 4.10-3San Carlos Airport Noise Contours


Not To Scale Source: Illingworth & Rodkin, 2009

55 CNEL

55 CNEL

60 CNEL65 CNEL

65 CNEL60 CNEL

55 CNEL


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Other Noise Sources

Noise sources that affect sensitive receptors within the community include industrial land uses, such as the Port of Redwood City (Port) and the associated heavy industrial uses, light industrial production, distribution, and repair (i.e., automobile repair) uses. Commercial and retail activities also serve as noise sources within the community that have the potential to affect sensitive receptors. These include gas stations, car washes, fire stations, air conditioning units, swimming pool pumps, school playgrounds, and public parks. Another source of noise in the plan area relates to intermittent construction activities. Construction noise can be significant for short periods of time at any particular location as a result of public improvement projects, private development projects, remodeling, etc. The implementation of standard controls, through the environmental review and permitting process, is used to regulate construction noise.

Planned/Programmed Improvements

California Department of Transportation Improvements

The California Department of Transportation (Caltrans) is planning for future highway improvements on U.S. 101, including improvements to the U.S. 101 and Woodside Road interchange. Improvements or changes to a major interchange can affect noise levels in surrounding areas. Interchange projects sponsored by the Caltrans are subject to environmental review pursuant to Caltrans and Federal Highway Administration (FHWA) requirements. Noise abatement measures are required if noise levels would approach or exceed the noise abatement criteria established by the FHWA. The noise abatement measures would normally mitigate any noise impacts associated with an interchange improvement project.

Ferry Terminal

The Water Emergency Transportation Authority (WETA) has proposed the development of a ferry terminal in Redwood City with service to San Francisco and the East Bay. The ferry terminal would be located on the north side of U.S. 101 in an industrial/commercial area. Noise sources associated with the ferry terminal include the ferry boats themselves, parking, and vehicular traffic accessing the terminal. Considering the limited noise sensitive land uses located on the north side of U.S. 101 in the plan area, it is not anticipated that the development and operation of a ferry terminal would cause a substantial increase in noise at any noise sensitive receptors in the community. Noise impacts associated with a new ferry terminal would be analyzed in detail as a part of the studies and environmental reviews prepared by WETA regarding a potential ferry service.

4.10.3 REGULATORY SETTING

2007 California Building Code, Title 24 Multi-family housing in the State of California is subject to the environmental noise limits set forth in the 2007 California Building Code (Chapter 12, Appendix Section 1207.11.2). The noise limit is a maximum interior noise level of 45 dBA Ldn/CNEL.


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Generally, interior noise levels for standard residential units are approximately 15 decibels lower than exterior noise levels with the windows partially open. Because of this, the California Building Code requires that when exterior noise levels exceed 60 dBA Ldn/CNEL, a report must be submitted with the building plans describing the noise control measures that have been incorporated into the design of the project to meet the interior noise level limit.

Redwood City Noise Ordinance Chapter 24 (Noise Regulation) of the Redwood City Municipal Code (the Noise Ordinance) sets allowable noise limits for different types of receiving land uses. The noise levels allowed by the Noise Ordinance depend primarily on the background noise level in the area. Section 24.21 prohibits noise increases of 6 decibels above local ambient measured noise at any point within a residential district due to an assembly of three or more people during the hours of 8:00 p.m. and 8:00 a.m. Section 24.32 of the Noise Ordinance establishes that noise levels generated by construction are prohibited between the hours of 8:00 p.m. and 7:00 a.m. weekdays, or at any time on Saturdays, Sundays, and holidays. In addition, Section 24.31 of the Noise Ordinance prohibits noise levels from exceeding 110 dBA for any item of machinery, equipment, or device used during construction in a residential district.

Redwood City Noise Standards The City addresses issues of land use compatibility, transportation noise, and community noise in the Noise Element of the existing General Plan. While the New General Plan would replace the established Noise Guidelines for Land Use Compatibility under the existing General Plan, the thresholds for acceptable noise conditions would generally remain the same for land use categories such as residential, commercial, industrial, and open space. As shown in Figure 4.10-4, normally acceptable noise levels of up to 55 dBA CNEL and conditionally acceptable levels of up to 70 dBA CNEL would be allowed for residential uses. Normally acceptable noise levels of up to 70 dBA CNEL and conditionally acceptable noise levels of up to 75 dBA CNEL would be permitted for commercial uses. Normally acceptable noise levels of up to 75 dBA CNEL would be permitted for industrial uses.

Vibration Criteria Presently, the City does not have any established vibration criteria or vibration limitations that can be used to evaluate the compatibility of sensitive land uses with respect to groundborne vibration related to railroads. While there are no City established vibration standards, both the U.S. Department of Transportation’s Federal Railroad Administration (FRA) and the U.S. Department of Transportation’s Federal Transit Administration (FTA) have developed vibration impact assessment criteria for evaluating vibration impacts associated with transit projects, which are based on maximum overall levels for a single event (i.e., a train passing by).


G 4.10-4Redwood City Noise Guidelinesfor Land Use Planning


Source:

Redwood

City

General

Plan, 2009


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Policy Consistency Analysis Compliance with Title 24 is a matter of law and any new development within the plan area would be required to maintain consistency with the California Building Code standards and Title 24 noise limitations. Regardless of New General Plan adoption, residential development projects in the plan area would be required to comply with the building code to ensure that interior noise levels would remain below 45 dBA Ldn/CNEL.

Additionally, New General Plan policies and implementation plans identified in Section 4.10.5, such as implementing building construction techniques and noise control measures, would ensure acceptable indoor and outdoor noise levels and would avoid, minimize, or reduce potential impacts to noise sensitive land uses, thus representing consistency with Sections 24.21, 24.31, and 24.32 of the Noise Ordinance.

In regards to the City’s noise regulations, with or without adoption of the New General Plan, the City’s noise standards, Noise Ordinance, and state regulatory requirements would be implemented for new development within the City at the time of preliminary development plans and tentative map applications. The noise environment in many portions of the plan area currently exceed the City’s noise level goal for exterior noise in residential areas(65 dBA CNEL) as a result of existing vehicular traffic noise sources within the plan area. However, New General Plan Policies PS-13.1 through PS-13.5 would require the establishment of noise level standards appropriate for all land uses, would revise the City’s Noise Ordinance to establish comprehensive noise control measures, and would strive to provide acceptable noise environments near noise-sensitive land uses, including schools, hospitals, and residential developments, which would further maintain noise standards within the plan area.

Although the City has no established vibration regulations, the New General Plan policies and implementation programs would employ vibration standards and would require the evaluation of sensitive land uses with respect to groundborne vibration. Program PS-65 requires the consideration of adoption of vibration standards and the codification of acceptable vibration levels within the City. As such, the City would consider the adoption of vibration criteria which would be considered and applied for all new development within the plan area. Additionally, Policy PS-13.7, although unrelated to railroad/transit sources, would require that mixed use structures be designed to minimize transfer of noise and vibration from commercial/retail to residential use.

4.10.4 THRESHOLDS OF SIGNIFICANCE Redwood City has not established local CEQA significance thresholds as described in Section 15064.7 of the State CEQA Guidelines. Therefore, significance determinations are from Appendix G of the CEQA Guidelines. A significant noise or vibration impact could occur if development allowed by the New General Plan would:

a) Expose people to or generate noise levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies.

b) Expose people to or generate excessive groundborne vibration or groundborne noise levels.


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c) Create a substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project.

d) Create a substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project.

e) 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 or public use airport, expose people residing or working in the project area to excessive noise levels.

f) For a project within the vicinity of a private airstrip, expose people residing or working in the project area to excessive noise levels.

4.10.5 ENVIRONMENTAL IMPACTS AND MITIGATION MEASURES The noise analysis is based on a comparison between existing and predicted noise levels and provides an evaluation of predicted noise levels relative to City noise standards. Noise impacts would be considered significant if either existing or proposed noise sensitive land uses would be exposed to noise or vibration levels in excess of the applicable standards. Significant effects could also occur if adoption of the New General Plan would substantially increase ambient noise levels or result in noise or vibration levels in excess of those listed in Section 4.10.3.

Issues Not Discussed Further Exposure to Excessive Noise Levels Within the Vicinity of a Private Airstrip

There are no private airstrips known to be located within or in the near vicinity of the plan area. The closest airport to the plan area is the San Carlos Airport, which is a public general aviation facility located along U.S. 101 near Redwood Shores. As such, the allowed development and the associated increase in population would not be exposed to excessive noise levels generated by a private airstrip.

Project Impacts Impact 4.10-1: Existing and future noise levels at the locations of proposed residences and other noise sensitive developments allowable under the New General Plan could exceed the City’s noise thresholds of acceptability. (Less than Significant)

Single-family residential development, schools, libraries, hospitals, convalescent homes, and places of worship are considered the most noise-sensitive land uses because of the quiet nature of onsite operations. Existing and future noise levels along many roadways in the plan area currently exceed “normally acceptable” exposure levels for these types of land uses, as shown in Figure 4.10-4. As such, noise levels at the locations of proposed residential developments and other noise sensitive land uses allowed under the New General Plan could exceed the City’s noise thresholds of acceptability. Figure 4.10-5 displays the projected 2030 noise contours in the plan area.

NOTE: Calculations assume an acoustically hard ground surfaceand do not take shielding from structures or barriers into account.Railroad noise levels are substantially higher near at-gradecrossings as a result of train warning whistles.


G 4.10-52030 Noise Contours in Plan Areafor Major Roadways and Railroads


Legend


NORTH

SCALE


CNEL Noise Levelin dB(A)

< = 5555 < < = 6060 <65 <70 <75 <

< = 65< = 70< = 75

0 1250 2500 5000Feet


M a y 2 0 1 0 D r a f t E I R 4.10-18

Existing and future traffic noise levels are shown in Table 4.10-6. As shown Figure 4.10-5 and as noted in Table 4.10-6, the areas receiving the most noise center around major roadways and the railroad.

Table 4.10-6 Existing and Future Noise Levels Along Roadways

Roadway Segment Speed (mph)

CNEL at 75 ft, dBA*

From To 2009 Existing 2030 Project

Alameda de las Pulgas

Woodside Rd Massachusetts Ave

30 63 63

Edgewood Rd Whipple Ave 30 65 65

Bay Rd Woodside Rd 5th Ave 30 67 69

Blomquist St Seaport Blvd Maple St 25 71 72

Brewster Ave Hudson St Broadway 25 63 63

Winslow St Veterans Blvd 30 68 68

Broadway Brewster Ave El Camino Real 30 64 64

Jefferson Ave Main St 30 68 68

Chestnut St Woodside Rd 30 69 70

Woodside Rd 5th Ave 30 72 72

Canyon Rd Oak Knoll Dr Farm Hill Blvd 25 57 57

Edgewood Rd Cordilleras Rd I-280 30 63 63

El Camino Real Woodside Rd 5th Ave 30 70 70

Whipple Ave City Limits 30 70 71

Farm Hill Blvd Mc Garvey Ave I-280 30 62 63

Hopkins Ave Hudson St Broadway 25 62 62

Hudson St Oak Ave Woodside Rd 25 62 63

Jefferson Ave Roosevelt Ave 30 63 64

Industrial Way Whipple Ave City Limits 35 73 74

Jefferson Ave Farm Hill Blvd Highland Ave 35 59 60


M a y 2 0 1 0 D r a f t E I R 4.10-19


CNEL at 75 ft, dBA*


Hudson St El Camino Real 25 68 68

Main St Broadway Middlefield Rd 30 67 68

Maple St El Camino Real Main St 25 71 71

Marine Pkwy Bridge Dr Shearwater Pkwy 35 64 66

Massachusetts Ave Alameda de las Pulgas

Woodside Rd 25 64 64

Mc Garvey Ave Farm Hill Blvd Alameda de las Pulgas

30 64 64

Middlefield Rd Woodside Rd 5th Ave 35 68 69

Redwood Shores Pkwy

US 101 Bridge Dr 35 69 70

Roosevelt Ave Alameda de las Pulgas

Valota Rd 30 63 63

Seaport Blvd Blomquist St Chesapeake Dr 35 68 70

Valota Rd Oak Ave Woodside Rd 30 60 60

Veterans Blvd Whipple Ave Brewster Ave 35 72 73

Whipple Ave Hudson St El Camino Real 35 66 67

Veterans Blvd Industrial Way 35 70 70

Winslow St Broadway Brewster Ave 30 67 68

Woodside Rd I-280 Alameda de las Pulgas

35 69 70

Alameda de las Pulgas

Massachusetts Ave

35 70 72

El Camino Real Middlefield Rd 35 71 72

Bay Rd Broadway 35 72 73

US 101 Willow Rd Marsh Rd 65 82 83

Marsh Rd Woodside Rd 65 82 83


M a y 2 0 1 0 D r a f t E I R 4.10-20


CNEL at 75 ft, dBA*


Woodside Rd Whipple Ave 65 81 82

Whipple Ave Holly St 65 83 84

Holly St Ralston Ave 65 81 82

I-280 Woodside Rd Farm Hill Blvd 65 81 81

Farm Hill Rd Edgewood Rd 65 81 82

Edgewood Rd SR 92 65 81 81

Note: Noise levels for major roadways are given at a distance of 75 feet from the center of the roadway. Noise levels for US 101 and I-280 are given at a distance of 75 feet from the center of the near travel lane. Source: Illingworth & Rodkin, 2010.

Mixed use development projects often include residential uses located above or in proximity to commercial uses. In the New General Plan, new, allowable mixed use development would be focused largely in areas served by rail and bus transit along major roadways and the railroad corridor. Among these areas are the El Camino Real/Caltrain (Union Pacific) railroad corridor, where noise exposure levels exceed those considered normally acceptable for residential uses.

Commercial development also contributes to noise at mixed use developments. Noise sources associated with commercial uses could include mechanical equipment operations, public address systems, parking lot noise (e.g., opening and closing of vehicle doors, people talking, car alarms), delivery activities (e.g., use of forklifts, hydraulic lifts), trash compactors, and air compressors. These elevated noise levels, which have the potential to be generated by commercial uses within mixed use developments, could expose nearby noise sensitive land uses to noise levels that exceed the City’s noise standards.

Additionally, industrial uses, if in close proximity to mixed use development, can contribute to noise impacts to sensitive receptors. In particular, the proposed Mixed Use – Waterfront Neighborhood under the New General Plan would be within close proximity to the Port and the associated industrial uses. Noise associated with Port activities, such as ship and machinery noise and truck traffic on Seaport Boulevard, could expose the nearby neighborhood to future noise levels beyond the City’s standard. Conversely, the industrial uses could be subject to new noise standards to ensure noise level compatibility with nearby residential and mixed use neighborhoods. The industrial uses, including those within the Port, could be subject to new limitations for noise intensive activities to keep noise levels at nearby residential and mixed use neighborhoods within City noise level standards.


M a y 2 0 1 0 D r a f t E I R 4.10-21

Where exterior transportation noise levels could exceed 60 dBA CNEL in new residential development, interior noise levels may exceed 45 dBA CNEL, in excess of what is permitted under Title 24. Interior noise levels within residential units with the windows partially open are approximately 15 decibels lower than exterior noise levels, assuming typical California Building Code construction methods. Interior noise levels are approximately 20-25 decibels lower than exterior noise levels with the windows closed, assuming typical California Building Code construction methods. Where exterior noise levels are 60 to 70 dBA CNEL, interior noise levels can typically be maintained below 45 dBA CNEL with the incorporation of an adequate forced air mechanical ventilation system in the residential units to allow residents the option of controlling noise by keeping the windows closed. In areas exceeding 70 dBA CNEL, the inclusion of windows and doors with high Sound Transmission Class (STC) ratings, and the incorporation of forced-air mechanical ventilation systems, may be necessary to meet 45 dBA CNEL.

The policies and implementation programs within the Public Safety Chapter of the New General Plan, listed in Appendix A, minimize the impacts of noise sources in the plan area through the establishment of noise level standards, noise regulation enforcement, and limiting hours of operation at all noise generation sources that are adjacent to noise sensitive areas. Adherence to the New General Plan policies would require the adoption and enforcement of noise level standards appropriate for all land use types. The policies would also prohibit allowing new development in areas where noise impacts could not be mitigated to an acceptable level. Additionally, the New General Plan would require the implementation of noise control measures that could ensure acceptable indoor and outdoor noise levels and avoid, minimize, or reduce potential impacts to noise sensitive land uses, as detailed in Policies PS-13.1 through PS-13.5, PS-13.9, PS-13.10, PS-14.1, PS-14.4, PS-14.5, and PS-14.6.

The New General Plan implementation programs require acoustical analyses for future development, require noise generating sources to be compatible with adjacent land uses, impose maintenance equipment restrictions, motor vehicle noise standards, and allowing for the appropriate enforcement of all noise regulations, including fines for violations. Noise impact analyses could be required for all new development within areas identified as currently having ambient noise levels above 60 dB CNEL. Additionally, the New General Plan would implement noise consultations with other governmental agencies to minimize transportation-related noise from freeways, major arterials, rail lines, and airports, as defined in Programs PS-59, PS-60, PS-61, PS-66, PS-67, PS-68, PS-71, PS-72, PS-73, and PS-75.

With adherence to these New General Plan policies and implementation programs, New General Plan impacts to noise sensitive land uses and areas would be less than significant at the program level. No additional mitigation is required. Individual developments within the plan area will be required to undergo project-specific environmental review. If individual projects within the plan area would result in the exceedance of the established noise standards, specific project-level mitigation measures will be required under CEQA.


M a y 2 0 1 0 D r a f t E I R 4.10-22

Impact 4.10-2: Ground vibration levels resulting from railroad train operations at the setback of proposed residences could exceed appropriate vibration thresholds and could expose people to groundborne vibration. (Less than Significant with Mitigation)

The New General Plan would not immediately result in the construction of any new vibration sensitive development. However, adoption of the New General Plan could result in the construction of buildings where known vibration sources exist, primarily along the existing active railroad corridor.

At this time, the City does not have its own standards for determining the severity of a vibration impact. However, vibration from railroad trains passing through the plan area could exceed the guidelines set forth by the FRA and/or FTA if new buildings are constructed within 100 feet of the railroad tracks. Under the New General Plan, a new mixed use residential land use designation is allowed on the El Camino Real Corridor. Some of the designation would be applied to lands within 100 feet of the Caltrain (Union Pacific) corridor. Residential development in this area, whether free-standing or part of a mixed use development, could result in ground vibration levels that would be noticeable and potentially adverse to residents of such developments.

Policy PS-13.7 of the New General Plan minimizes the impacts of groundborne vibration in the plan area by requiring that mixed use structures be designed to minimize the transfer of vibration from commercial to residential use. Program PS-65 encourages the City to adopt of City-wide vibration standards, that if adopted would ensure vibration effects are addressed more comprehensively.

While the New General Plan policies and implementation programs could minimize the transfer of vibration from commercial to residential use, New General Plan program PS-65 would only consider the adoption of vibration standards, rather than requiring implementation, and would not address vibration transfer from transportation infrastructure, such as the Caltrain (Union Pacific) corridor. Thus, Mitigation Measure 4.10-1 would be required, in addition to the New General Plan policies and implementation programs, to ensure that program-level vibration impacts are reduced to a less than significant level.

In addition, the City will require that individual development projects undergo project-specific environmental review. If project-level significant vibration impacts are identified, specific mitigation measures will be required under CEQA.

Mitigation Measure 4.10-1: The City shall revise the New General Plan to include a new policy and implementation program that requires vibration-sensitive buildings (including but not limited to residential buildings) to be sited at least 100 feet from the centerline of railroad tracks, whenever feasible. The policy and implementation program shall also require the preparation of a site-specific vibration study for any residential or vibration-sensitive development proposed within 100 feet of the centerline of the railroad tracks. The study shall include recommended measures to reduce vibration to meet City-side vibration standards, as defined per Program PS-65 of the New General Plan. Potential measures to reduce vibration include, but are not limited to, modifications in sit planning or building construction. The City shall


M a y 2 0 1 0 D r a f t E I R 4.10-23

include the recommendation(s) of site-specific vibration studies as conditions of any subsequent project approvals involving potentially significant vibration impacts.

Significance After Mitigation: With the implementation of Mitigation Measure 4.10-1, which would require buffers between vibration-sensitive buildings and vibration sources and site-specific vibration studies, potential vibration impacts would be reduced to less than significant at the programmatic level.

Impact 4.10-3: Estimated increased vehicular traffic and transportation and infrastructure improvements allowed for by the New General Plan could result in a permanent increase in ambient noise levels. (Less than Significant)

The increased development allowed under the New General Plan would result in an increase in vehicular traffic, which would increase traffic noise in the plan area. To determine how changes in vehicular traffic volumes and flow would affect noise levels in the plan area, traffic noise levels were modeled for future development conditions allowed under the New General Plan for the year 2030. The traffic projections included in this analysis assumed traffic growth due to the allowed development under the New General Plan, as well as other planned development in surrounding areas. The following future transportation and infrastructure improvements in the plan area were also considered when modeling future traffic flow conditions.

Blomquist Extension

The Blomquist extension from Maple Street to the East Bayshore Road/Bair Island Road intersection would provide a two-lane collector street serving nearby businesses and industries. Sensitive land uses allowed for the area of the Blomquist extension include mixed use waterfront neighborhoods. However, based on the data presented in Table 4.10-6, the Blomquist extension would not increase noise levels by more than 1 dBA in the area proposed for mixed use waterfront neighborhoods. As such, the General Plan would not affect the noise environment at any noise sensitive receptors in the surrounding areas. Impacts related to the development of sensitive land uses in areas already exceeding applicable noise standards are discussed under Impact 4.10-1.

Grade Separations at Rail Crossings

The plan area includes a number of at-grade rail crossings along the Caltrain (Union Pacific) rail corridor. Grade separations are anticipated to occur where the Caltrain tracks intersect with Whipple Avenue, Hopkins Avenue, Brewster Avenue, Broadway, Depot Circle, Maple Street, Main Street, and Chestnut Street. The City’s future grade separations will maintain roadway grade; tracks will be fully depressed or fully elevated. Along these lines, Policy BE-29.8 calls for consideration of the replacement of the existing grade separation near El Camino Real/Woodside Road with a solution that would allow the roadway to remain at grade and require the railroad to be depressed or bridge over the roadway.

Given the range of possibilities, it is difficult to quantitatively evaluate changes in roadway traffic noise and railroad train noise as a result of these grade separations. However, qualitatively, the grade separations can be expected to result in a substantial


M a y 2 0 1 0 D r a f t E I R 4.10-24

reduction in railroad train noise because the railroad trains would not be required to sound their warning horns. Overall, grade separations are anticipated to result in a positive impact on the plan area’s noise environment.

Pedestrian Enhanced Designs

The New General Plan allows for a reduction in the number and/or width of lanes along several roadways in the plan area. These Pedestrian Enhanced Designs (PEDs) can serve as an important tool in traffic calming that normally leads to reductions in vehicular traffic noise. The traffic noise reductions and improvements occur as a result of a reduction in vehicular traffic speed and a smoothing of the traffic noise, which results from the more continuous flow of traffic along the roadways. The PEDs would be expected to improve the plan area’s noise environment.

Streetcar Network

The New General Plan allows for a fixed route streetcar network consisting of up to three lines that could intersect in downtown. The streetcar system could operate within existing travel lanes, following fixed guideways connected by aerial or catenary wires. Streetcars are potentially a source of noise and groundborne vibration. Typically, at the relatively low speeds that urban streetcar systems operate, these systems can be designed and constructed incorporating controls so as not to cause significant noise or vibration impacts. All such systems are subject to environmental review, including detailed noise and vibration studies. Streetcar systems have been incorporated into numerous communities, including San Jose, with less than significant noise and vibration impacts. A streetcar system, incorporating appropriate controls, would not be expected to have an adverse impact on the community’s noise and vibration environment. If and when more precise plans for a streetcar network are introduced, the City will evaluate these plans under CEQA.

At the program level, the projected year 2030 noise levels were compared to the existing conditions in order to determine whether the project would result in a substantial permanent increase in ambient noise levels in the plan area. A review of the data presented in Table 4.10-6 shows that noise levels in the plan area could typically increase by less than 2 dBA CNEL or less between 2009 and 2030 with adoption of the New General Plan. As previously discussed, the human ear does not typically notice changes in a noise level of less than 3 dBA.

As such, the increase in vehicular traffic resulting from the allowed development would not significantly increase noise levels in the plan area. With adherence to and adoption of New General Plan policies and implementation programs, impacts related to increased noise levels would be less than significant. No additional mitigation is required. Individual developments within the plan area will be required to undergo project-specific environmental review. If significant project-level noise impacts are identified, specific mitigation measures will be required under CEQA.


M a y 2 0 1 0 D r a f t E I R 4.10-25

Impact 4.10-4: Construction noise caused be development allowed under the New General Plan would cause a temporary or periodic increase in noise exposure above ambient levels. (Less than Significant)

Development allowed by the New General Plan could reasonably be expected to generate noise during construction. Construction activities can generate considerable amounts of noise, especially when heavy equipment is used during both construction and demolition activities. While adoption of the New General Plan would not result in any immediate construction, adoption of the New General Plan would allow for an increment of new development over existing levels.

Construction-related noise levels typically range from about 80 to 90 dBA at a distance of 50 feet from the noise source. Pile driving can cause levels up to 100 105 dBA at 50 feet. Typical hourly average construction generated noise levels are about 81 dBA to 89 dBA measured at a distance of 50 feet from the center of the site during busy construction periods. Construction generated noise levels drop off at a rate of about 6 dBA per doubling of distance between the source and receptor.

Several policies and implementation programs within the Public Safety Chapter of the New General Plan, including Policies PS-13.6 and PS-13.8 and Programs PS-62, PS-74, and PS-79, would minimize the impacts of temporary construction noise in the plan area by requiring all exterior noise sources to use noise suppression devices to bring noise levels to an acceptable level, implementing standard construction noise controls, enforcing existing construction and maintenance hours, and educating construction workers and developers regarding noise reduction measures. Refer to Appendix A for a detailed list of the New General Plan policies and implementation programs.

Adherence to the above listed policies and implementation programs would effectively reduce temporary construction noises in the plan area and reduce program level effects to a less than significant level. No additional mitigation is required. Individual developments within the plan area will be required to undergo project-specific environmental review. If project-level impacts are identified and are found to be significant, CEQA requires that these impacts be mitigated.

Impact 4.10-5: Aircraft noise over proposed areas where residential use would be allowed under the New General Plan would exceed City noise thresholds, which could expose individuals living and working within the plan area to excessive noise levels. (Less than Significant with Mitigation)

The New General Plan would allow for an increment of new residential development in areas where aircraft noise levels exceed 55 dBA CNEL, particularly in waterfront neighborhoods. City and County Airport Land Use Plan Guidelines consider such noise levels excessive for new residential development.

Policies and programs in the New General Plan govern new development proposed for areas susceptible to noise associated with the San Carlos Airport. As shown in Appendix A, Policies PS-14.2 and PS-14.3 and Programs PS-63 and PS-64 require that proposed land uses within the identified noise contours of the San Carlos Airport be reviewed by the Airport Land Use Commission, mitigate for potential noise impacts, and


M a y 2 0 1 0 D r a f t E I R 4.10-26

maintain consistency with the aircraft noise/land use compatibility standards in the San Mateo County Airport Land Use Plan. These New General Plan policies and implementation programs would relate to local land use policy actions, such as a General Plan Amendment or zoning amendment. These policies and implementation programs would also require the City to continue to coordinate with the San Mateo County Department of Public Works Airport Division and the Federal Aviation Administration to develop programs to minimize noise impacts from aircraft functions and evaluate the consistency of new development with the San Mateo County Comprehensive Airport Land Use Plan.

While these New General Plan policies and implementation programs would ensure compliance with the local airport land use plans, the New General Plan policies do not provide an objective performance standard or threshold with which new development within the identified aircraft noise area must comply. Thus, Mitigation Measure 4.10-2 would be required to modify the language of New General Plan Policy PS-14.2 to identify a threshold of meeting applicable City noise standards for mitigating potential noise impacts to a less than significant level.

Mitigation Measure 4.10-2: The City shall revise New General Plan Policy PS-14.2 to include a threshold for noise impact mitigation for development within the identified aircraft noise contours. The revision shall be as follows:

Policy PS-14.2: Require that proposed land use policy actions (such as a General Plan Amendment, zoning amendment, or a Precise Plan) within the identified aircraft noise contours for San Carlos Airport are:

Reviewed by the Airport Land Use Commission (C/CAG Board)

Mitigated for potential noise impacts, as appropriate to applicable City noise standards, by the developer;

Consistent with the Aircraft Noise/Land Use Compatibility Standards in the San Mateo County Airport Land Use Plan.”

Significance After Mitigation: Implementation of Mitigation Measure 4.10-2 would reduce noise impacts resulting from potential aircraft noise to a less than significant level.

Documents

4.10 NOISE AND VIBRATION