Present measurement data in well -organized tables and figures with a summary and interpretation of measured data. Measurements are often included in the table of measurement sites described in the previous paragraph. In some cases, measurements may be supplemented or replaced by collected data relevant to the noise and vibration characteristics of the area. For example, soil information for estimating ground -borne vibration propagation characteristics may be available from other projects in the area.
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A summary and interpretation of how the collected data define the project setting is fundamental to this section.
2b. Direct Impacts — Include the following in the discussion on direct impacts due to project operation:
• Overview of approach — Provide a targeted summary of relevant information on the assessment procedure for determining noise/vibration impacts as a framework for the following sections. • Estimated noise/vibration levels — Provide a general description of prediction models used to estimate project noise/vibration levels.
Describe any distinguishing features unique to the project, such as source levels associated with various technologies.
Describe the results of the predictions in general terms first, followed by a detailed accounting of predicted noise levels. Supplement this information with tables and illustrate by contours, cross -sections, or shaded mapping. If contours are included in a technical report, it is not necessary to repeat them in this section.
• Criteria for noise/vibration impact — Describe the impact criteria for the project in detail and reference the appropriate section in this manual. Include tables listing the criteria levels or the figures included in this manual.
• Noise/vibration impact assessment — Present the impact assessment in its own section or combined with the section above.
Describe the locations, as identified in the screening procedure, where noise/vibration impact is expected to occur without implementation of mitigation measures, based on the screening results, predicted future levels, existing levels, and application of the impact criteria.
Include inventory tables of impacted noise- and vibration -sensitive sites to quantify the impacts for all noise/vibration-sensitive sites included in the Affected Environment (Existing Conditions) as described in the Existing Conditions section above.
• Noise/vibration mitigation measures — Perhaps the greatest difference between the technical report and the environmental document is with mitigation. The technical report discusses mitigation options and recommendations, while the environmental document provides the vehicle for reaching decisions on appropriate mitigation measures.
Begin this section with a summary of the noise/vibration mitigation measures considered for the impacted locations. Describe the specific measures selected for implementation in detail. Also, include any FEDERAL TRANSIT ADMINISTRATION 191
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applicable, specific noise or vibration policies the project sponsor may have in place.
In cases where it is not possible to commit to a specific mitigation measure in the final environmental document, it may be possible to commit to a certain noise/vibration level. For example, the environmental document could include a commitment to meet or exceed the impact criteria specified in Sections 4. I and 6.2. ■ Unavoidable adverse environmental effects — If it is projected that adverse noise/vibration impacts will result after all reasonable abatement measures have been incorporated, identify these impacts in this section.
2c. Construction Impacts — Discuss construction impacts in the environmental document's section on construction impacts, if present.
If, because of the scale of the project, the environmental document does not have a separate construction impacts section, then the construction impacts should be discussed with the rest of the resource impacts.
When a special section on construction noise/vibration impacts is included in the document, it should be organized according to the comprehensive outline on long-term impacts described above. For projects with relatively minor effects, include a brief summary of impact.
8.2 Technical Report on Noise and Vibration
The technical report is intended to present complete technical data and descriptions in a manner that can be understood by the general public, but is more technical than the information found in the environmental document. All necessary background information should be present in the technical report, including tables, maps, charts, drawings, and references that may be too detailed for the environmental document, but which are important in helping to draw conclusions about the project's noise and vibration impacts and mitigation options.
Include the following major subject headings and key information described below. If both noise and vibration have been assessed, include separate sections for noise and vibration with subsections for key information as described below.
Additional details on documentation requirements for the technical report of non-standard procedures and methodologies are included in Appendix G. ■ Overview — Include a brief description of the project and an overview of the noise/vibration concerns to highlight initial considerations in framing the scope of the study.
■ Inventory of Noise/Vibration-Sensitive Sites — Describe the approach for identifying noise- and vibration -sensitive sites as well as the identified sites and site descriptions. Use sufficient detail to demonstrate completeness. Document results on a map.
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■ Measurements of Existing Noise/Vibration Conditions
▪ Document the basis for selecting measurement sites, including tables of sites coordinated with maps showing locations of sites.
Summarize the measurement approach with justification for the measurement procedures used.
• If the measurement data are used to estimate existing conditions at other locations, include the rationale and the method of estimation.
Describe measurement procedures in detail.
▪ Include tables of measurement instruments documenting manufacturer, type, serial number, and date of most recent calibration by authorized testing laboratory. Document
measurement periods, including the time of day and length of time at each site to demonstrate adequate representation of ambient conditions.
▪ Present measurement data in well -organized tables and figures with a summary and interpretation of measured data.
■ Additional Measurements Related to the Project — Include detailed description of measurements and results for projects that require specialized measurements at noise- and vibration -sensitive sites.
Examples include:
▪ Outdoor -to -indoor noise level reduction of homes
• Transmission of vibration into concert halls and recording studios • Special source -level characterization
■ Predictions of Noise/Vibration from the Project
▪ Describe the prediction model used to estimate future project conditions and specific data used as input to the models. Reference the appropriate section in this manual. Document any change or extension to the models recommended in this manual, so that the validity of the adjustments can be confirmed. See Appendix G for more information.
▪ Describe in detail the modeled scenarios and why the scenarios were chosen.
▪ Tabulate computed levels and illustrate by contours, cross -sections, or shaded mapping. Illustrate noise/vibration impacts with base maps at a scale with enough detail to provide reference for the location. ■ Noise/Vibration Criteria
• Describe the impact criteria for the project in detail and reference the appropriate section in this manual. Include tables specifying the criteria levels or the figures included in this manual. • If construction noise and/or vibration assessments were conducted, include the construction criteria in a separate section with the construction assessment details. See below for more information.
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■ Noise/Vibration Impact Assessment
▪ Describe the impact assessment according to the appropriate noise and/or vibration impact assessment sections in this manual. ▪ If an alternatives analysis was conducted, present a resulting impact inventory for each alternative mode or alignment in a format that allows comparison among alternatives.
• Tabulate the inventory according to the different types of affected noise- and vibration -sensitive sites. Present the results of the assessment both before and after mitigation.
• Noise/Vibration Mitigation
• Begin this section with a summary of all treatments considered, including those not carried to final consideration.
• Consider final candidate mitigation treatments separately and provide a description of the features of the treatment, including costs, expected benefit in reducing impacts, locations where the benefit would be realized, and a discussion of the practicality of alternative treatments.
▪ Include enough noise and vibration impact information to allow the project sponsor and FTA to reach decisions on mitigation prior to issuance of an environmental decision document.
• Construction Noise/Vibration Impacts
▪ Describe criteria adopted for construction noise or vibration if construction noise and/or vibration assessments were conducted. ▪ Describe the method used for predicting construction noise or vibration and include inputs to the models such as equipment roster by construction phase, equipment source levels, assumed usage factors, and other assumed site characteristics.
▪ Present predicted levels for noise- and vibration -sensitive sites and identify short-term impacts.
• In cases where construction impacts are identified, discuss feasible abatement methods using enough detail to allow construction contract documents to include mitigation measures.
• References — Provide references for all criteria, approaches, and data used in the analyses, as well as other reports related to the project that may be relied on for information, e.g., geotechnical reports.
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Appendix A: Glossary of Terms
Terminology used through the manual is defined in this appendix.(49)(72) A -weighting
A standardized filter used to alter the sensitivity of a sound level meter with respect to frequency so that the instrument is less sensitive at low and high frequencies where the human ear is less sensitive. Abbreviated as dBA.
Absolute Noise
Impact
Noise that interferes with activities independent of existing noise levels and is expressed as a fixed level threshold.
Accelerometer
A transducer that converts vibratory motion to an electrical signal proportional to the acceleration of that motion.
Ambient
The pre -project background noise or vibration level, which is often used interchangeably with "existing noise" in this manual.
Amplitude
Difference between the extremes of an oscillating signal.
Alignment
The horizontal location of a railroad or transit system as described by curved and tangent track.
At -grade
Tracks on the ground surface.
Automated Guideway
Transit (AGT)
Guided steel -wheel or rubber -tired transit passenger vehicles operating singly or in multi -car trains with a fully automated system on fixed -guideways along an exclusive ROW. AGT includes personal rapid transit, group rapid transit, and automated people mover systems.
Auxiliaries
The term applied to a number of separately driven machines, operated by power from the main engine or electric generation. They include the air compressor, radiator fan, traction motor blower, and air conditioning equipment.
Ballast mat
A 2- to 3 -inch -thick elastomer mat placed under the normal track ballast on top of a rigid slab or packed sub -grade.
Ballast
Granular material placed on the trackbed for the purpose of holding the track in line and at surface.
Bus Rapid Transit
(BRT)
A type of limited -stop bus operation that relies on technology to help speed up the service. Buses can operate on exclusive transitways, high -occupancy -vehicle lanes, expressways, or ordinary streets.
Catenary
On electric railroad and LRT systems, the term describing the overhead conductor that is contacted by the pantograph or trolley, and its support structure.
Commuter rail
Conventional passenger railroad serving areas surrounding an urban center. Most commuter railroads utilize locomotive -hauled coaches, often in push-pull configuration.
Consist
The total number and type of cars, locomotives, or transit vehicles in a trainset.
Continuous welded
rail
A number of rails welded together to form unbroken lengths of track without gaps or joints.
Corrugated rail
A rough condition of alternating ridges and grooves which develops on the rail head in service.
Crest factor
The ratio of peak particle velocity to maximum RMS amplitude in an oscillating signal.
Criteria
Plural form of "criterion," the relationship between a measure of exposure (e.g., sound or vibration level) and its corresponding effect.
Cross tie
The transverse member of the track structure to which the rails are spiked or otherwise fastened to provide proper gage and to cushion, distribute, and transmit the stresses of traffic through the ballast to the trackbed.
Crossover
Two turnouts with the track between the frogs arranged to form a continuous passage between two nearby and generally parallel tracks.
Cumulative
The summation of individual sounds into a single total value related to the effect over time.
Cut
A terrain feature typically created to allow for a trackbed to be at a lower level than the surrounding ground.
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dB
See Decibel.
dBA
See A -weighting.
Decibel
The standard unit of measurement for sound pressure level and vibration level.
Technically, a decibel is the unit of level which denotes the ratio between two quantities that are proportional to power; the number of decibels is I 0 times the logarithm of this ratio. Abbreviated as dB.
DMU
Diesel -powered multiple unit. See Multiple Unit.
DNL
See Ld,,.
Electrification
A term used to describe the installation of overhead wire or third rail power distribution facilities to enable operation of trains.
Embankment
A bank of earth, rock, or other material constructed above the natural ground surface.
Equivalent level
The level of a steady sound, which, in a stated time period and at a stated location, has the same sound energy as the time -varying sound. Also, written as Leq.
Event
A passby of a vehicle (e.g., train, bus, or car) of any size consist.
Ferry boat
A transit mode comprised of vessels to carry passengers and/or vehicles over a body of water.
Fixed guideway
A public transportation facility with a separate ROW for the exclusive use of public transportation and other high -occupancy vehicles.
Flange
The vertical projection along the inner rim of a wheel that serves, together with the corresponding projection of the mating wheel of a wheel set, to keep the wheel set on the track.
Floating slab
A special track support system for vibration isolation, consisting of concrete slabs supported on resilient elements, usually rubber or similar elastomer.
Force density
Force density is the force per root distance along the track in Ib/ft"2. The force density level is the level in decibels of the force density relative to I lb/ft' and describes the vehicle force that excites the soil/rock surrounding the transit structure.
Frequency
The number of times that a periodically occurring quantity repeats itself in a specified period. With reference to noise and vibration signals, the number of cycles per second.
Frequency spectrum
Distribution of frequency components of a noise or vibration signal.
Frog
A track structure used at the intersection of two running rails to provide support for wheels and passageways for their flanges, thus permitting wheels on either rail to cross the other.
Gage (of track)
The distance between the rails on a track.
Grade crossing
The point where a rail line and a motor vehicle road intersect at the same vertical elevation.
Guideway
Supporting structure to form a track for rolling or magnetically -levitated vehicles.
Head -End Power
(HEP)
A system of furnishing electric power for a complete railway train from a single generating plant in the locomotive.
Heavy rail
See Rail Rapid Transit.
Hertz (Hz)
The unit of acoustic or vibration frequency representing cycles per second.
Hourly average sound
level
The time -averaged A -weighted sound level, over a I -hour period, usually calculated between integral hours. Abbreviated as L(Ih).
Hybrid Bus
A rubber -tired vehicle that features a hybrid diesel-electric propulsion system. A diesel engine runs an electric generator that powers the entire vehicle including electric drive motors that deliver power to the wheels.
Idle
The speed at which an engine runs when it is not under load.
Intermediate Capacity
Transit (ICT)
A transit system with less capacity than rail rapid transit (RRT), but more capacity than typical bus operations. Examples of ICT include bus rapid transit (BRT), automated guideway transit (AGT), monorails, and trolleys.
Intermodal facility
Junction of two or more modes of transportation where transfers may occur.
Jointed rail
A system of joining rails with steel members designed to unite the abutting ends of contiguous rails.
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L(Ih)
See Hourly Average Sound Level.
Ldp
Day -Night Sound Level. The sound exposure level for a 24 -hour day calculated by adding the sound exposure level obtained during the daytime (7 a.m. to I 0 p.m.) to I 0 times the sound exposure level obtained during the nighttime (10 p.m. to 7 a.m.).
This unit is used throughout the United States for environmental impact assessment.
Also, written as DNL.
Leg('hr) time
Equivalent Sound Level. The metric for cumulative noise exposure over a specific interval is the equivalent sound level
Light Rail Transit
(LRT)
A mode of public transit with tracked vehicles in multiple units operating in mixed traffic conditions on streets as well as sections of exclusive ROW. Vehicles are generally powered by electricity from overhead lines.
Locomotive
A self-propelled, non -revenue rail vehicle designed to convert electrical or mechanical energy into tractive effort to haul railway cars. See also Power Unit.
Main line
The principal line or lines of a railway.
Maglev
Magnetically -levitated vehicle; a vehicle or train of vehicles with guidance and propulsion provided by magnetic forces. Support can be provided by either an electrodynamic system wherein a moving vehicle is lifted by magnetic forces induced in the guideway or an electromagnetic system wherein the magnetic lifting forces are actively energized in the guideway.
Maximum sound level
The highest exponential -time -average sound level, in decibels, that occurs during a stated time period. Abbreviated as Lmax. The standardized time periods are 1 second for Lmax, slow, and 0.125 second for Lm,., fast.
Metric
Measurement value or a quantitative descriptor used to identify a specific measure of sound level.
Monorail
Guided transit vehicles operating on or suspended from a single rail, beam, or tube.
Multimodal Project
In this manual, the term multimodal project is used to describe a project that includes changes to both transit and highway components in segments of the project.
Multiple Unit (MU)
A term referring to the practice of coupling two or more diesel -powered or electric - powered passenger cars together with provision for controlling the traction motors on all units from a single controller.
Noise
Any disagreeable or undesired sound or other audible disturbance.
Octave band
A standardized division of a frequency spectrum in which the interval between two divisions is a frequency ratio of 2.
One-third octave
band
A standardized division of a frequency spectrum in which the octave bands are divided into thirds for more detailed information. The interval between center frequencies is a ratio of 1.25.
Pantograph
A device for collecting current from an overhead conductor (catenary), consisting of a jointed frame held up by springs or compressed air and having a current collector at the top.
Park -and -ride facility
A parking garage and/or lot used for parking passengers' automobiles while they use transit agency facilities and vehicles.
Peak factor
See Crest factor.
Plan -and -profile
Mapping used by transportation planners that shows two-dimensional plan views (x - and y- axes) on the same page as two-dimensional profiles (x- and z-axes) of a road or track.
Peak Particle Velocity
(PPV)
The peak signal value of an oscillating vibration velocity waveform. Usually expressed in inches/second in the United States.
Peak -to -Peak (P -P)
Value
Of an oscillating quantity, the algebraic difference between the extreme values of the quantity.
Power unit
A self-propelled vehicle, running on rails and having one or more electric motors that drive the wheels and thereby propel the locomotive and train. The motors obtain electrical energy either from a rail laid near, but insulated from, the track rails, or from a wire suspended above the track. Contact with the overhead wire is made by a pantograph mounted on top of the unit.
Project segment
Portions of a project with similar characteristics.
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Pure tone
Sound of a single frequency.
Radius of curvature
A measure of the severity of a curve in a track structure based on the length of the radius of a circle that would be formed if the curve were continued.
Rail
A rolled steel shape, commonly a T -section, designed to be laid end to end in two parallel lines on cross ties or other suitable supports to form a track for railway rolling stock.
Rail Rapid Transit
(RRT)
Often called "Heavy Rail Transit." A mode of public transit with tracked vehicles in multiple units operating in exclusive rights -of -way. Trains are generally powered by electricity from a third rail alongside the track.
Receiver
A stationary far -field position at which noise or vibration levels are specified.
Relative Noise Impact
Noise increase above existing levels.
Resonance frequency
The phenomenon that occurs in a structure under conditions of forced vibration such that any change in frequency of excitation results in a decrease in response.
Right -of -Way
Abbreviated as ROW. Lands or rights used or held for railroad or transit operation.
Root Mean Square
(rms)
The square root of the mean -square value of an oscillating waveform, where the mean -square value is obtained by squaring the value of amplitudes at each instant of time and then averaging these values over the sample time.
RMS Velocity Level
(LV)
See Vibration Velocity Level.
SEL
See Sound Exposure Level.
Sound Exposure Level
The level of sound accumulated over a given time interval or event. Technically, the sound exposure level is the level of the time -integrated mean square A -weighted sound for a stated time interval or event, with a reference time of one second.
Abbreviated as SEL.
Sound
A physical disturbance in a medium that is capable of being detected by the human ear.
Spectrum
See Frequency Spectrum.
Sub -ballast
Any material of a superior character, which is spread on the finished subgrade of the roadbed and below the top -ballast, to provide better drainage, prevent upheaval by frost, and better distribute the load over the roadbed.
Subgrade
The finished surface of the roadbed below the ballast and track.
Suburban bus
A bus similar to an intercity bus with high-backed seats but no luggage compartment, often used in express mode to city centers from suburban locations.
Switch
A track structure used to divert rolling stock from one track to another.
Tangent track
Track without curvature.
Track
An assembly of rail, ties, and fastenings over which cars, locomotives, and trains are moved.
Traction motor
A specially designed direct current series -wound motor mounted on the trucks of locomotives and self-propelled cars to drive the axles.
Trainset
A group of coupled cars including at least one power unit.
Transducer
Device designed to receive an input signal of a given kind (motion, pressure, heat, etc.) and to provide an output signal of a different kind (electrical voltage, amperage, etc.) in such a manner that desired characteristics of the input signal appear in the output signal for measurement purposes.
Transfer mobility
Transfer mobility is the complex velocity response produced by a point force as a function of frequency and represents the relationship between a vibration source that excites the ground and the resulting vibration of the ground surface.
Transit center
A fixed location where passengers interchange from one route or vehicle to another.
Trolley bus
A rubber -tired, electrically -powered bus operating on city streets drawing power from overhead lines.
Truck
The complete assembly of parts including wheels, axles, bearings, side frames, bolster, brake rigging, springs, and all associated connecting components, the function of which is to provide support, mobility, and guidance to a railroad car or locomotive.
Trunk line
See Mainline. The mainline of a commuter railroad where the branch line traffic is combined.
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Turnout
An arrangement of a switch and a frog with closure rails, by means of which rolling stock may be diverted from one track to another.
VdB
See Vibration Velocity Level.
Vibration Velocity
Level (LV)
Ten times the common logarithm of the ratio of the square of the amplitude of the RMS vibration velocity to the square of the amplitude of the reference RMS vibration velocity. The reference velocity in the United States is one micro -inch per second.
Abbreviated as VdB.
Vibration
An oscillation wherein the quantity is a parameter that defines the motion of a mechanical system.
Wheel flat
A localized flat area on a steel wheel of a rail vehicle, usually caused by skidding on steel rails, causing a discontinuity in the wheel radius.
Wheel squeal
The noise produced by wheel -rail interaction, particularly on curves where the radius of curvature is smaller than allowed by the separation of the axles in a wheel set.
Additional, relevant acoustic terminology and formulas are defined in ANSI SI.I-1994 (49).
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Appendix B: Fundamentals of Noise
Noise is generally considered to be unwanted sound. Sound is what we hear when our ears are exposed to small pressure fluctuations in the air. There are many ways in which pressure fluctuations are generated, but typically they are caused by vibrating movement of a solid object. This manual uses the terms noise and sound interchangeably because there is no physical difference between them. Noise can be described in terms of three variables: amplitude (loud or soft); frequency (pitch); and time pattern (variability).
B. I Amplitude
The loudness of a sound is described by the sound wave's amplitude of pressure fluctuations above and below atmospheric pressure. Pressure is measured in Pascals. The mean value of the positive and negative pressure fluctuations is the static atmospheric pressure and is not a useful metric of sound.
However, the effective magnitude of the sound pressure in a sound wave can be expressed by the rms of the oscillating pressure. See Figure B- I for an illustration of the rms pressure.
The rms pressure is calculated according to Eq. B-1. The values of sound pressure are squared and time - averaged to smooth out variations. The rms pressure is the square root of this time -averaged value. where:
Prms
Pi
N
i=1
Prms
N
N P`
i=1
= sound pressure
= individual sound pressure
= number of samples
= index of summation
Eq. B- I
Figure B -I RMS Pressure Illustration
Most humans with typical or average hearing can perceive sounds ranging from approximately 20 microPascals to 20 million microPascals or more. Because of the difficulty in dealing with such an extreme range of numbers, acousticians use a logarithmic scale to describe sound levels. Acousticians use a compressed scale based on logarithms of the ratios of the sound energy contained in the wave related to the square of sound pressures instead of the sound pressures themselves, resulting in the "sound pressure level" in decibels (dB). The 'B' in dB is always capitalized because the unit is named after Alexander Graham Bell, a leading I 9th century innovator in communication.
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Sound pressure level (LP) is defined as:
Prms
Lp = 101og10 ( 2 ); or
Pref
where
Lp
Prms
Pref
Lp = 201og10(Prms) dB
Pref
= sound pressure level, dB
= RMS sound pressure
= 20 microPascals
Eq. B-2
Inserting the range of sound pressure values mentioned above into Eq. B-2 results in a typical quietest sound at 20 microPascals at 0 dB. A typical loudest sound of 20 million microPascals is 120 dB.
B. I. I Decibel Addition
The combination of two or more sound pressure levels at a single location requires decibel addition, which is the addition of logarithmic quantities of sound energy (Prrms).
To add sound energy from multiple, unique sources, add the sound energy as shown Eq. B-3. where
P12+P22+...+Pn2
Lp = 101oYio( 2
Pref
Lp
P1, P2,Pn
Pref
)
= sound pressure level, dB
= individual source RMS sound pressures to add
= 20 microPascals
Eq. B-3
A doubling of identical sound sources results in a 3 -dB increase, as shown mathematically below.
Lp = 101Og10 (2 PrPrms )e
f
Prms
= 10loglo ( 2 ) + 101°910 (2)
Pre f
P7 -ms
= 101ogio( 2 ) + 3
Pref
To add decibel levels (instead of sound energy) use the following equation:
N
Lp = 101°910(10(Lt/1o) )
i=1
where
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Lp
N
Li
Lp
L1, L2,Ln
= sound pressure level, dB
= number of samples
= index of summation
= individual sound pressure levels, dB
= sound pressure level, dB
= individual source sound pressure levels to add
The equation above can be rewritten as follows:
L1 L2 Ln
Lp = 10log10(1010 + 1010 + •••+ 1010) Eq. B-4
where
L1, L2,Ln = individual source sound pressure levels to add Decibel addition can be quickly approximated using Figure B-2. a)
.0
a)
O
a)
E
a)
0 C
0 0 2 4 6 8 10 12 14
Difference in Decibels
Between Two Levels To Be Added
16 Figure B-2 Graph for Approximate Decibel Addition
18 20
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Example B- I Decibel Addition — Identical Buses
Decibel Addition
What is the combined sound pressure level of two identical buses if the noise from one bus resulted in a sound pressure level of 70 dB?
Since a doubling of identical sound sources results in a 3 -dB increase:
Lp = 70+3
= 73 dB
Example B-2 Decibel Addition - Two Sources
Decibel Addition
What is the combined sound pressure level of 64 dB and 60 dB? Using Eq. B-4:
Lp = 10logio(1064/10 + 1060/10)
= 65.5 dB
Using Figure B-2:
The x-axis values represent the difference between the two sound levels, 64 and 60 dB. The difference between the sound levels in this example is 4. The point on the curve corresponding to 4 on the x-axis is 1.5. The y-axis values represent the increment that is added to the higher level.
Lp = 64 + 1.5
= 65.5 dB
B.I.2 Frequency
Sound is a fluctuation of air pressure. The number of times the fluctuation occurs in one second is called its frequency. In acoustics, frequency is quantified in cycles per second, or Hertz (Hz). The hearing for a typical human covers the frequency range from 20 Hz to 20,000 Hz.
Some sounds, like whistles, are associated with a single frequency; this type of sound is called a pure tone. However, most often, noise is made up of many frequencies, called a spectrum. Analyzing a noise spectrum allows for identification of dominant frequency ranges and can assist in identifying noise sources. Often a frequency spectrum is divided into standardized frequency bands for analysis. Most commonly, the frequency bands for transit analyses are octave bands (where the interval between two divisions is a frequency ratio of 2) and one-third octave bands (where the interval between center frequencies is a ratio of I .25).(73)
If the spectrum associated with a transit noise source is dominated by many low -frequency components, the noise will have a characteristic like the rumble of thunder; this is often associated with noise from a subway. Mid -range frequencies are often associated with wheel/rail noise, and high frequencies may be associated with wheel squeal due to sharp curves on a track.
The spectrum in Figure B-3 illustrates the full range of acoustical frequencies that can occur near a transit system. In this example, the noise spectrum was measured near a train on an elevated steel structure with a sharp curve.
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120
1/3 Octave Band Sound Pressure Level -- dB Re 20uPa
110
100
90 80
70 60
50 Rumble Roar Squeal
31.5 63 125 250 500 1000 2000 4000 8O00
ai C,
Octave Band of Transit Train on Elevated Structure -- Hz Figure B-3 Noise Spectrum of Transit Train on Curve and Elevated Structure The human auditory system does not respond equally to all frequencies of sound. For sounds normally heard in our environment, low frequencies below 250 Hz and frequencies above 10,000 Hz are generally considered less audible than the frequencies in between. This is because our ears are less sensitive in those areas. To better represent human hearing, frequency response functions were developed to characterize the way people respond to different frequencies. These are referred to as A-, B-, and C - weighted curves and represent human auditory response to normal, very loud, and extremely loud sound levels, respectively. Environmental noise is generally considered to be in the normal sound level range; and, therefore, the A -weighted sound level is considered best to represent the human response.
The A -weighting curve is shown in Figure B-4. This curve illustrates that sounds at 50 Hz would have to be amplified by 30 dB to be perceived as loud as a sound at 1000 Hz at normal sound levels.
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Relative Response (dB)
10 0
-10
-20
-30
-40
-50
2 10 2 5 100 2 5 1000
Frequency (Hz)
Figure B-4 A -Weighting Curve
5 10,000
Low frequencies have longer wavelengths of sound (cycles are less frequent) and, conversely, high frequencies have shorter wavelengths (cycles are more frequent). The size of the wavelength in feet is dependent on frequency and speed of sound as follows:
where
f2 = c
f = frequency in cycles per second, Hz
A = wavelength, ft
c = speed of sound, ft/sec
Eq. B-5
The speed of sound in air varies with temperature; but at standard conditions, it is approximately 1000 ft per second. Therefore, at standard conditions, a frequency of 1000 Hz has a wavelength of I foot and a frequency of 50 Hz has a wavelength of 20 ft. The scale of these waves explains, in part, the reason humans perceive sounds of 1000 Hz better than those of 50 Hz. A wavelength of I foot is similar to the size of a person's head; whereas, a wavelength of 20 ft is similar to dimensions associated with a house, which is why low -frequency sounds (such as those from an idling locomotive) are sometimes not attenuated by walls and windows of a home. These sounds transmit indoors with relatively little reduction in strength.
B.I.3 Time Pattern
The third important characteristic of noise is its variation in time. Environmental noise is considered to be a combination of all outdoor noise sources. When combined, sources such as distant traffic, wind in trees, and distant industrial or farming activities often create a low-level background noise in which no particular individual source is identifiable. Background noise is often relatively constant from moment to moment, but varies slowly over time as natural forces change or as human activity follows its daily cycle.
In addition to this low-level, slowly varying background noise, a succession of identifiable noisy events of relatively brief duration may be added. These events may include single -vehicle passbys, aircraft flyovers, FEDERAL TRANSIT ADMINISTRATION 205
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screeching of brakes, and other short-term events, which all cause the noise level to substantially fluctuate from moment to moment.
It is possible to describe these fluctuating noises in the environment using single -number metrics to allow for manageable measurements, computations, and impact assessment. The search for adequate single -number noise metrics has encompassed hundreds of attitudinal surveys and laboratory experiments in addition to decades of practical experience with many alternative metrics.
B.I.4 Noise Metrics
The noise metrics referred to in this manual are described in the sections below.
B. I.4. I A -weighted Sound Level: The Basic Noise Unit The basic noise unit for transit noise is the A -weighted sound level and is described in ANSI S1.1-1994 (49). It describes the noise level at the receiver at any moment in time and can be read directly from noise -monitoring equipment when frequency weighting is set to A -weighting. Figure B-5 shows examples of typical A -weighted sound levels for both transit and non -transit sources, ranging from approximately 30 dBA (very quiet) to 90 dBA (very loud).
The unit dBA denotes the decibel level is A -weighted. The letter "A" indicates that the sound has been filtered to reduce the strength of very low and very high -frequency sounds to emulate the human response to sound levels as described in Appendix B. I.2. This allows for events that are out of the range of human hearing, such as high -frequency dog whistles and low -frequency seismic disturbances, to be filtered out. On average, each A -weighted sound level increase of I 0 dB corresponds to an approximate doubling of subjective loudness.
A -weighted sound levels are adopted as the basic noise unit for transit noise impact assessments because they:
• Can be measured easily,
• Approximate the human ear's sensitivity to sounds of different frequencies, • Match attitudinal -survey tests of annoyance better than other basic units, • Have been in use since the early 1930s, and
• Are endorsed as the proper basic unit for environmental noise by most agencies concerned with community noise throughout the world.
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Transit Sources
Rail Transit on Old Steel Structure.
50 mph
Rail Transit Horn
Rail Transit on Modern Concrete
Aerial Structure. 50 mph
Rail Transit At -Grade. 50 rapt;,
City Pus. Riling
Rail Transit in Station
All at 50 t1
dBA Non -Transit Sources
Outdoor Indoor
Rock Drill
Jack Hammer
Concrete Mixer
Alr Compressor
Lawn Mower
Lawn Tiller
Air Cond toner
All at 50 fl
Figure B-5 Typical A -weighted Sound Levels
Shop Tools, In use
Shop Tools. Idling
Food Blender
Clothes Washer
Air Conditioner
Refrigerator
All at 3 tt
B. I.4.2 Maximum Sound Level (Lm,x) During a Single Noise Event As a transit vehicle approaches, passes by, and then recedes into the distance, the A -weighted sound level rises, reaches a maximum, and then fades into the background noise. The maximum A -weighted sound level reached during this passby is called the maximum sound level, (49) abbreviated here as Lmax.
Lmax is illustrated in Figure B-6 where time is plotted horizontally, and A -weighted sound level is plotted vertically.
Although Lora,, is commonly used in vehicle -noise specifications,xvi it is not used for transit environmental noise impact assessment. Lma, does not include the number and duration of transit events, which are important for assessing people's reactions to noise. It also cannot be normalized to a one -hour or 24 -hour cumulative measure of impact, and therefore, is not conducive to comparison among different transportation modes. For example, cumulative noise metrics commonly used in highway noise assessments are Leq(Ihr) and L10, the noise level exceeded for '0 percent of the peak hour. xv, For noise compliance tests of transient sources, such as moving transit vehicles under controlled conditions with smooth wheel and rail conditions, Lmax is typically measured with the sound level meter's time weighting set to "fast." However, for tests of continuous or stationary transit sources, it is usually more appropriate to use the "slow" setting. When set to "slow," sound level meters ignore some of the very -transient fluctuations, which are negligible when assessing the overall noise level.
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.r 90 _
cn
V
ai
a.)
a 80
U)
V
a)
a)
i 70 _
0 Lmax = 88
SEL-89.6
4 8 12 16 20 24 28 Seconds
Figure B-6 Typical Transit -Vehicle Passby
B. I.4.3 Sound Exposure Level (SEL): Exposure from a Single Noise Event
Sound exposure level, abbreviated here as SEL, is the cumulative noise exposure from a single noise event, normalized to one second (49). SEL contains the same overall sound energy as the actual varying sound energy during the event. It is the primary metric for the measurement of transit vehicle noise emissions and an intermediate metric in the measurement and calculation of both Leq(Ihr) and Ldp. The SEL metric is A -weighted and is expressed in the unit dBA.
This concept is illustrated in Figure B-6 and Figure B-7 where the shaded regions are the sound exposure during and event. The example in Figure B-6 is a transit -vehicle passby and Figure B-7 is an example of a fixed -transit facility as a transit bus is started, warmed up, and then driven away. For this event, the noise exposure is large due to duration of the event.
SEL is an A -weighted cumulative measure that is referenced to one second. Louder events have greater SELs than quieter events, and events of longer duration have greater SELs than shorter events. This is generally consistent with community response to noise. Noise events of longer duration are considered more disruptive than events of shorter duration with equal maximum A -weighted sound levels.
A -Weighted Sound Level, dBA
90 80
70 _
0 SEL = 89.6
Lmax = 82
ifliPVAMIV 41/11\
8 12 16 20 24 28 Seconds
Figure B-7 Typical Fixed -Facility Noise Event
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Conceptually, the sound exposure level can be expressed as:
SEL = 101og10(Total sound energy )
during the event
Mathematically, the sound exposure level is computed as follows:
N
where
SEL = 101°910(11 0(Li/10) )
SEL
N
Li
i=1
= Sound exposure level, dBA
= number of samples
= index of summation
= individual A -weighted sound level, dBA
Eq. B-6
The events shown in Figure B-6 and Figure B-7 are compared graphically in Figure B-8 using a logarithmic vertical scale. The shaded zones in these figures indicate noise exposure over time. The actual event shows the noise exposure over the time of the event, and the equivalent SEL shows the total noise exposure normalized to one second. Note that events I and 2 in Figure B-8 have different time periods and noise levels throughout the event, but the same resulting SEL.
SEL is used in transit noise analyses because it:
I. Accounts for both the duration and amplitude of an event,
2. Allows a uniform assessment method for both transit -vehicle passbys and fixed -facility noise events, and
3. Can be used to calculate the one -hour and 24 -hour cumulative metrics for comparison across different transportation modes.
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A -Weighted Sound Level, d8A
o
85 80
75 Zero Energy 70
Event 1: Loud Noise for
Event 2: Lower Maximum Level
Short Duration for Longer Duration
Squeezed SEL
Actual Event
Squeezed SEL
Actual Event
0 4 8 12 16 20 24 — 'r— 0 4 8 12 16 20 24
Time Axis 1 sec.
Figure B-8 An Energy View of Noise
B. I.4.4 Equivalent Sound Level (Leq(t))
Time Axis 1 sec.
Events
The metric for cumulative noise exposure over a specific time interval is the equivalent sound level (49).
It is a single decibel value that accounts for total sound energy from all sound levels over a specified time interval (or time period). The time period associated with the equivalent sound level metric can vary for different types of analyses. This metric is abbreviated as Leq(c), where "t" is the duration of the time period. Leq(,) represents a hypothetical constant sound level and contains the same overall sound energy as the actual varying sound energy during the time period "t". For most transit noise analyses, an A - weighted, hourly equivalent sound level is used, abbreviated here as Leq(Ihr). Leq(Ihr) is expressed in the unit, dBA.
Figure B-9 shows examples of typical unmitigated hourly Leq(Ihr) 's, both for transit and non -transit sources ranging from 40 (quiet) to 80 dB (loud). Note that these Leq(Ihr) 's depend upon both the number of events during the hour as well as each event's duration, which is affected by vehicle speed. For example, doubling the number of events during the hour will increase the Leq( I hr) by 3 decibels, as will doubling the duration of each individual event.
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Transit Sources Lpr, Non -Transit Sources
Commuter Trains at 50 mph,
6 per Hour with Horn Blowing —I"
Commuter Trains al 50 mph
6 per Hour
Rail Transit Trains at 40 mph
12 per Hour
Rail Transit Trains at 20 mph
12 per Hour
All at 50 ft
10 90
&0
70 60
50 40
— 8 -Lane Highway
- 6 -Lane Highway
.— 4 -Lane Urban Arterial Road
-4— 2 -Lane Suburban Arterial Road
All at 50 ft
Figure B-9 Typical Hourly Leg(' hr)
An example of sound levels over time for a single noise event such as a train passing on nearby tracks is illustrated in the top frame of Figure B- I O. As the train approaches, passes by, and then recedes into the distance, the A -weighted sound level rises, reaches a maximum, and then fades into the background noise. The equivalent sound level is shown for three different time periods Figure B -I O. The area under the curve in this top frame is the noise that reaches the receiver (noise exposure) over this five-minute period. The center frame of the figure shows sound levels over the one -hour period, including the five- minute period from the top frame. The area under the curve represents the noise exposure for one hour. The bottom frame shows sound levels over a full 24 -hour period and is discussed in Appendix B.I.4.5.
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5 Minutes
00 85 a-
80 -
4 75
-70
Uy
c�
55 50
Sound Level, dBA
45 -
40 Lmax (86 dBA)
Leq (5 min) = 65 dBA
Leq(1 sec)
15:25 -' 1525
90 85
15:27 15:20 15:29 _. 1530
-.--� 1 Hour
00-
75 70
65 60
55 50
45 Leq(1 hr) = 61 dBA
1 • •
40 J.: •
Leq(5 sec)
15:00 f57T--. 15.10 15:15 1520 7525 15:31; 15:35 15:40 15:45 15:50 155 .- 16:03 45 00 00
02:00
04:00
06:00
0s:00
1500
280
1430
18:00
0:00
20:00
22:09
Ldn = 62 dBA
Leq(24 hr) = 57 dBA
Typical A -weighted Sound Level Variation over a 24 -Hour Period Figure B -I0 Example A -weighted Sound Level Time Histories Conceptually, the equivalent sound level can be expressed as:
Total Sound Energy
Leg(t) = 101og10( Time Period )
24 Hours
241+0
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Mathematically, the equation is as follows:
N
Leq(t) = 1010 1I 10(Lt/1o))
91o(T
i=1
where
Leq(t)
T
N
Li
= equivalent sound level of time period "t", dBA
= time period, sec (3600 for an hourly Leq(Ihr))
= number of samples, sec (3600 for an hourly Leq(Ihr))
= index of summation
= individual A -weighted sound level, dBA
The equation above can be rewritten as follows for a one -hour time period:
Lea(1h) = 101og10[Total Sound Energy in 1 hr] — 35.6
where
35.6 = numerical adjustment for a time period of I hour (I Ologio(t)) Eq. B-7
The sound energy is totaled over a full hour (3600 seconds) and is accumulated for all noise events during that hour. When computing the equivalent sound level for a time period other than one hour, T is modified in the equation to the duration of the time period in seconds. The numerical adjustment (35.6) accounts for time period of interest, in this case, one hour.
An alternate way for computing Leq(Ihr)for a series of transit -noise events using sound exposure levels can be expressed conceptually as follows:
L Energy Sum of ) 35.6
eq (1h ) = 1010 910 ( all SELs
Mathematically, the equation is as follows:
where
N
Leq(t) = 101ogio(- 10(set,i/10))
T
i=1
Leq(t)
T
N
SEL
= equivalent sound level of time period "t", dBA
= time period, sec (3600 for an hourly Leq(Ihr))
= number of sample, sec (3600 for an hourly Leq(Ihr))
= index of summation
= individual sound exposure level, dBA
Eq. B-8
Hourly Leq(Ihr) is adopted as the measure of cumulative noise impact for non-residential land uses (those not involving sleep) because Leq(Ihr):
• Correlates well with speech interference in conversation and on the telephone — as well as interruption of TV, radio, and music enjoyment;
• Increases with the duration of transit events;
• Accounts for the number of transit events over the hour, which is also important to people's reactions; and
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■ Is used by the Federal Highway Administration in assessing highway -traffic noise impact.(Thus, this noise metric can be used for directly comparing and contrasting highway, transit, and multimodal alternatives).
B. I.4.5 Day -Night Sound Level (Ldn): 24 -Hour Exposure from All Events
The metric for cumulative 24 -hour exposure is the Day -Night Sound Level, (49) abbreviated here as Ldn.
It is a single, A -weighted decibel value that accounts for total sound energy from all sound sources over 24 hours and is expressed in the unit, dBA. Events between I O p.m. and 7 a.m. are increased by I O dB to account for people's greater nighttime sensitivity to noise.
Figure B- I I shows examples of typical Ldn's, both for transit and non -transit sources, ranging from 50 to 80 dB, where 50 is considered a quiet 24 -hour period and 80 a loud 24 -hour period. Note that these Ldn's depend upon the number of events during day and night separately, including each event's duration, which is affected by vehicle speed.
Transit Sources
Commuter Train with Horn at 40 mph
Loco + 8 Cars
15 Day, 3 Night
Rail Transit at 40 mph
6 -Car Trains
30O Day, 18 Night
Commuter Train at 40 mph
Loco + 8 Cars
15 Day, 3 Night
Rail Transit at 20 mph
2 -Car Trains
300 Day, 18 Night
All at50ft
Lin Background Noise
o
g0
80 70
50 40
- Downtown City
- "Very Noisy" Urban Residential Area
"Quiet" Urban Residential Area
Suburban Residential Area
Small Town Residential Area
Figure B- I I Typical Ldn's
An example of sound level variation over 24 hours is visualized in the bottom frame of Figure B- I O. The area under the curve represents the receiver's noise exposure over the 24 hours. Note that some vehicle passbys occur at night, when the background noise is typically lower and the I O dB adjustment is applied.
Conceptually, the day -night level can be expressed as:
Total Sound EnergyDay nadj,n x Total Sound EnergyNiyht
Ldn = 1010-10(Time PeriodDay (seconds) + Time PeriodNiynr (seconds) FEDERAL TRANSIT ADMINISTRATION 214
Mathematically, the equation is as follows:
N M
Ldn = 10109100 ti x 10(Ld,t/10) + tj x 10((Ln,j+nadjn)/1o)) Td i=1 Tn j=1
where
Ldn
Td
N
ti
Tn
M
j
tj
Ln,1
nad j,n
= cumulative 24 -hour exposure (day -night sound level), dBA = time period during the daytime, between 7 a.m. and 10 p.m. sec (54,000) = number of samples during the daytime (54,000)
= index of summation
= time interval of measurements in seconds (I)
= individual A -weighted sound level during the daytime, dBA = time period during the nighttime, between I O p.m. and 7 p.m. sec (32,400) = number of samples during the nighttime (32,400)
= index of summation
= time interval of measurements, sec (I)
= individual A -weighted sound level during the nighttime, dBA = nighttime noise adjustment (I0 dB)
The equation above can be rewritten as follows:
Ldn = 10loglo[ (15 * Total Sound Energyoay) + (9 * nadj,n * Total Sound EnergyNtyht)] — 49.4 Eq. B-9
The sound energy is totaled over a full 24 hours, and the sound energy is accumulated from all noise events during that time period. The numerical adjustment (49.4) accounts for time period of interest, in this case, 24 hours.
An alternative way of computing Ldp from twenty-four hourly Leq(Ihr) 's can be expressed conceptually as follows:
Energy sum of Energy sum of
daytime, hourly Legs + (nadj,n * nighttime, hourly Legs) Ldn = 101og10( Time period (seconds) )
The equation above can be rewritten as:
Energy sum of Energy sum of
daytime, hourly Legs + (nadj,n * nighttime, hourly Legs) Ldn = 101og10( 86400
(3600)
The equation above can be reduced further and rewritten as:
L — 1010 Energy sum of + n * Energy sum of 13.8
Ldn — -1o(daytime, hourly Legs ( adj,n nighttime, hourly Legs)) Eq. B- I 0
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Ldn due to a series of transit -noise events can also be computed in terms of SEL. The equation below assumes that transit noise dominates the 24 -hour noise environment, where nighttime SELs are increased by I O dB before totaling:
L 10lo = Energy sum of + n * Energy sum of 49.4
dn. glo(all daytime SELs ( adj,n all nighttime SELs--
Eq. B- I I
Ldn is adopted as the measure of cumulative noise impact for residential land uses (those involving sleep), because it:
• Correlates well with the results of attitudinal surveys of residential noise impact • Increases with the duration of transit events
• Accounts for the number of transit events over the full twenty-four hours ■ Accounts for the increased sensitivity to noise at night, when most people are asleep ■ Allows composite measurements to capture all sources of community noise combined • Allow quantitative comparison of transit noise with other community noises • Is the designated metric of choice of other Federal agencies (e.g., HUD, FAA, and EPA) and has wide international acceptance
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Appendix C: Background for Transit Noise Impact
Criteria
The noise criteria presented in Section 4. I of this manual have been developed based on well - documented criteria and research on human response to community noise. The primary goals in developing the noise criteria were to ensure that the impact limits are firmly founded in scientific studies, realistically based on noise levels associated with new transit projects, and represent a reasonable balance between community benefit and project costs. This appendix provides background information on the development of these criteria.
C. I Relevant Literature
The following is an annotated list of the documents that are particularly relevant to the noise impact criteria:
I. U.S. EPA's "Levels Document"(74)
This report identifies noise levels consistent with the protection of public health and welfare against hearing loss, annoyance, and activity interference. It has been used as the basis of numerous community noise standards and ordinances.
2. Committee on Hearing, Bioacoustics and Biomechanics (CHABA) Working Group 69, "Guidelines for Preparing Environmental Impact Statements on Noise"(75) This report was the result of deliberations by a group of leading acoustical scientists with the goal of developing a uniform national method for noise impact assessment. Although the CHABA's proposed approach has not been adopted, the report serves as an excellent resource documenting research in noise effects. It provides a strong scientific basis for quantifying impacts in terms of Ldn.
3. American Public Transportation Association (APTA) Guidelines for Design of Rapid Transit Facilities(76)
The noise and vibration sections of the APTA Guidelines have been used successfully in the past for the design of rail transit facilities. The APTA Guidelines include criteria for acceptable community noise and vibration. Experience has shown that meeting the APTA Guidelines will usually result in acceptable noise levels; but the metric used in the APTA Guidelines is not appropriate for environmental assessment purposes.
The APTA Guidelines criteria are in terms of Lmax for conventional RRT vehicles, and they cannot be used to compare among different modes of transit. Since the APTA Guidelines are expressed in terms of maximum passby noise, they are not sensitive to the frequency or duration of noise events for transit modes other than conventional RRT operations with 5 to 10 minute headways. Therefore, the APTA criteria are questionable for assessing the noise impact of other transit modes that differ from conventional rapid transit with respect to source emission levels and operating characteristics (e.g., commuter rail, AGT, and a variety of bus projects).
4. Synthesis of Social Surveys on Noise Annoyance(77)
In 1978, Theodore J. Schultz, an internationally known acoustical scientist, synthesized the results of a large number of social surveys concerning annoyance due to transportation noise. A group of these surveys were remarkably consistent, and the author proposed that their average FEDERAL TRANSIT ADMINISTRATION 217
results be taken as the best available prediction of transportation noise annoyance. This synthesis has received essentially unanimous acceptance by acoustical scientists and engineers.
The "universal" transportation response curve developed by Schultz (Figure 3-7) shows that the percent of the population highly annoyed by transportation noise increases from zero at an Ldn of approximately 50 dBA to 100% when Ldn is approximately 90 dBA. Most importantly, this curve indicates that for the same increase in Ld", there is a greater increase in the number of people highly annoyed at high noise levels than at low noise levels. For example, a 5 dB increase at low ambient levels (40 - 50 dB) has less impact than at higher ambient levels (65 - 75 dB). A recent update of the original research containing several railroad, transit, and street traffic noise surveys, confirming the shape of the original Schultz curve (12).
5. HUD's Standards(19)
HUD has developed noise standards, criteria, and guidelines to ensure that housing projects supported by HUD achieve the goal of a suitable living environment. The HUD acceptability standards define 65 dB (Ldn) as the threshold for a normally unacceptable living environment (moderate impact for FTA) and 75 dB (Ldn) as the threshold for an unacceptable living environment (severe impact for FTA).
C.2 Basis for Noise Impact Criteria Curves
The lower curve in Figure 4-2 represents the onset of moderate impact and is based on the following considerations:
• The EPA finding that a community noise level of Ldn less than or equal to 55 dBA is "requisite to protect public health and welfare with an adequate margin of safety."(72) ■ The conclusion by EPA and others that a 5 dB increase in Ldn or Leq(Ihr) is the minimum required for a change in community reaction.
• The research concludes that there are very few people highly annoyed when the Ldn is 50 dBA, and that an increase in Ldn from 50 dBA to 55 dBA results in an average of 2% more people highly annoyed (Figure 3-7).
The increase in noise level from an existing ambient level of 50 dBA to a cumulative level of 55 dBA because of a project is found to cause minimal impact, with 2% of people highly annoyed, as described in the bullets above. This is considered the lowest threshold where impact starts to occur. Therefore, for an existing ambient noise level of 50 dBA, the curve representing the onset of moderate impact is at 53 dBA, the combination of which yields a cumulative level of 55 dBA by decibel addition. The remainder of the lower curve in Figure 4-2 was determined from the annoyance curve (Figure 3-7) by allowing a fixed 2% increase in annoyance at other levels of existing ambient noise. As cumulative noise increases, the increment to attain the same 2% increase in highly annoyed people is smaller. While it takes a 5 -dB noise increase to cause a 2% increase in highly annoyed people at an existing ambient noise level of 50 dB, an increase of only I dB causes a 2% increase of highly annoyed people at an existing ambient noise level of 70 dBA.
The upper curve in Figure 4-2 represents the onset of severe impact based on a total noise level, corresponding to a higher degree of impact. The severe noise impact curve is based on the following considerations:
• HUD defines an Ldn of 65 as the onset of a normally unacceptable noise zone (moderate impact for FTA) in its environmental noise standards (19). FAA considers that residential land uses are not compatible with noise environments where Ldn is greater than 65 dBA (20).
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■ An increase of 5 dB in Ldn or Leq(t) is commonly assumed as the minimum required increase for a change in community reaction.
■ The research concludes that an increase of 5 dB in Ldn or Le(*) represents a 6.5% increase in the number of people highly annoyed (Figure 3-7).
The increase in noise level from an existing ambient level of 60 dBA to a cumulative level of 65 dBA caused by a project represents a change from an acceptable noise environment to the threshold of an unacceptable noise environment. This is considered the level at which severe impact starts to occur with a 6.5% increase in the number of people highly annoyed as described in the bullets above.
Therefore, for an existing ambient noise level of 60 dBA, the curve representing the onset of severe impact is at 63 dBA, the combination of which yields a cumulative level of 65 dBA by decibel addition.
The remainder of the upper curve in Figure 4-2 was determined from the annoyance curve (Figure 3-7) by allowing a fixed increase of the 6.5% increase in annoyance at all existing ambient noise levels.
Both curves incorporate a maximum limit for the transit project noise in noise -sensitive areas.
Independent of existing noise levels, moderate impact for land use categories I and 2 is considered to occur whenever the transit Ldn equals or exceeds 65 dBA, and severe impact occurs whenever the transit Ldn equals or exceeds 75 dBA. These absolute limits are intended to restrict activity interference caused by the transit project alone.
Both curves also incorporate a maximum limit for cumulative noise increase at low existing noise levels (below approximately 45 dBA). This is a conservative limit that reflects the lack of social survey data on people's reactions to noise at such low ambient levels. Like the FHWA approach in assessing the relative impact of a highway project, the transit noise criteria include limits on noise increase of I 0 dB and 15 dB for moderate impact and severe impact, respectively, relative to the existing noise level.
Note that due to the types of land use included in category 3, the criteria allow the project noise for category 3 sites to be 5 dB greater than for category I and category 2 sites. This difference is reflected by the offset in the vertical scale on the right side of Figure 4-2. Aside from active parks, which are clearly less sensitive to noise than category I and 2 sites, category 3 sites include primarily indoor activities. Therefore, the criteria account for some noise reduction from the building structure.
C.3 Equations for Noise Impact Criteria Curves
The equations for the noise impact criteria curves shown in Figure 4-2 are included in this section.
These equations may be useful when performing the noise assessment methodology using spreadsheets, computer programs, or other analysis tools. Otherwise, such mathematical detail is generally not necessary to implement the criteria, and direct use of Figure 4-2 is adequate and less time-consuming.
A total of four continuous curves are included in the criteria, creating two threshold curves for moderate and severe impact for category I and 2, and two curves for category 3 (See Table C- I ). Note that for each level of impact, the overall curves for categories I and 2 are offset by 5 dB from category
3. While each curve is graphically continuous, each one is defined by a set of three discrete equations.
These equations are approximately continuous at the transition points. The following is a description of the three equations:
■ The first equation in each set is a linear relationship, representing the portion of the curve in which the existing noise exposure is low, and the allowable increase is limited to 10 dB and 15 dB for moderate impact and severe impact, respectively.
FEDERAL TRANSIT ADMINISTRATION 219
• The second equation in each set represents the impact threshold over the range of existing noise exposure for which a fixed percentage of increase in annoyance is allowed, as described in Appendix C.2. This curve is a third -order, polynomial approximation derived from the Schultz curve(75) and covers the range of noise exposure encountered in most populated areas. This curve is used for determining noise impact in most cases for transit projects. • The third equation represents the absolute limit of project noise imposed by the criteria for areas with high existing noise exposure. For land use category I and 2, the absolute limit is 65 dBA for moderate impact and 70 dBA for severe impact. For land use category 3, the absolute limit is 75 dBA for moderate impact and 80 dBA for severe impact.
Table C -I Threshold of Moderate and Severe Impacts
Threshold of Moderate Impact
Category I and 2
Category 3
11.450 + 0.953LE, LE 71
16.450 + 0.953LE, LE 71
Eq. C- 12
Eq. C- 13
Threshold of Severe Impact
Category I and 2
17.322 + 0.940LE, LE 77
Category 3
22.322 + 0.940LE, LE 77
Eq. C- 14
Eq. C- 15
LE = the existing noise exposure in terms of Lan or Leq(Ihr) [p = the project noise exposure which determines impact in terms of Ldn or Leq(Ihr)) FEDERAL TRANSIT ADMINISTRATION 220
Appendix D: Clustering Receivers of Interest
This appendix supplements the information in Section 4.5 on clustering receivers of interest.
The general approach to selecting noise -sensitive receivers in the study area is included in Section 4.5, Step I. General guidelines are as follows:
• Select the following types of receivers to evaluate individually:
▪ Every major noise -sensitive public building
▪ Every isolated residence
▪ Every relatively small outdoor noise -sensitive area
• Residential neighborhoods and relatively large outdoor noise -sensitive areas can often be clustered and represented by a single receiver.
Clustering similar receivers reduces the number of computations needed later, especially for large-scale projects where a greater number of noise -sensitive sites may be affected. For this approach to be effective, it is essential that the representative receiver accurately represents the noise environment of the cluster.
The major steps in clustering receivers include:
I. First, cluster receivers according to approximately equal exposure to the primary project noise source. These areas typically run parallel to a linear project or circle major stationary sources relative to the proposed project.
2. Next, cluster receivers according to major sources of ambient noise. These areas typically run parallel to or encircle major sources of ambient noise.
3. Then, cluster receivers according to changes in the project layout or operations along the corridor.
4. Finally, select a representative receiver for each cluster.
The major steps are expanded below and include instructions on how to draw cluster boundaries on a map.
I. Boundaries along the proposed project — Draw cluster boundaries along the proposed project as described below to separate clusters based on distance from the project. Draw these cluster boundaries for the project sources listed as major in Table 4-19.
Within both residential and noise -sensitive outdoor areas:
■ Primary project source
Draw cluster boundaries at the following distances from the near edge of the primary project source: 0 ft, 50 ft, 100 ft, 200 ft, 400 ft, and 800 ft. For linear sources, such as a rail line, draw these boundaries as lines parallel to the proposed ROW line. For stationary sources, draw these boundaries as approximate circles around the source, starting at the property line.
Do not extend boundaries beyond the noise study area, identified in the Noise Screening Procedure in Section 4.3 or the General Noise Assessment of Section 4.4.
FEDERAL TRANSIT ADMINISTRATION 221
• Remaining project sources — Repeat the process for the primary project source for all other project listed as major in Table 4-19, such as substations and crossing signals. If several project sources are located approximately together, only consider one source, since the others would produce approximately the same boundary.
It is good practice to optimize the number of clusters for a project to simplify the procedure.
Where rows of buildings parallel the transit corridor:
• Ensure that cluster boundaries fall between the following rows of buildings, counting back away from the proposed project:
▪ Between rows I and 2
• Between rows 2 and 3
• Between rows 3 and 4
• Add cluster boundaries between these rows if not already included.
2. Boundaries along sources of ambient noise — Draw cluster boundaries along all major sources of ambient noise based upon distance from these sources, as described below. • Draw cluster boundaries along all interstates and major roadway arterials at the following distances from the near edge of the roadway: 0 ft, I00 ft, 200 ft, and 500 ft. • Draw cluster boundaries along all other roadways that have state or county numbering at 0 ft and 100 ft from the near edge of the roadway.
• For all major industrial sources of noise, draw cluster boundaries that encircle the source at the following distances from the near property line of the source: 0 ft, 100 ft, 200 ft, and 400 ft.
3. Boundaries based on changes in project layout or operations — Further subdivision is needed to account for changes in project noise where proposed project layout or operating conditions change considerably along the corridor. Draw a cluster boundary perpendicular to the corridor extending straight outward to both sides at the following locations:
• Where parallel tracks previously separated by more than approximately 100 ft are moved closer together
• Approximately where speed and/or throttle are reduced when approaching stations and where steady service speed is reached after departing stations • Approximately 200 ft up and down the line from grade crossing bells • At transitions from jointed to welded rail
• At transitions from one type of cross section to another including on structure, on fill, at -grade and in cut
• At transitions from open terrain to heavily wooded terrain • At transitions between areas free of locomotive horn noise and areas subject to this noise source
• Any other positions along the line where project noise is expected to change considerably, such as up and down the line from tight curves where wheels may squeal
4. Selection of a representative receiver from each cluster — Determine a representative receiver for each cluster boundary drawn in the steps above. • Residential clusters
Select a representative receiver within the cluster at the house closest to the proposed project.
If this receiver is not the clear choice, select the receiver furthest from major sources of ambient noise.
• Outdoor noise -sensitive clusters (e.g., urban park or amphitheater) FEDERAL TRANSIT ADMINISTRATION 222
Select a representative receiver within the cluster at the closest point of active noise -sensitive use. If this receiver is not the clear choice, select the receiver farther from major sources of ambient noise.
Note that some clusters may fall between areas with receivers of interest. This could occur when operational changes or track layouts change in an open, undeveloped area. Retain these clusters. Do not merge them with adjacent clusters. Do not select a representative receiver of interest from them.
Example D- I Clustering Receivers
Receivers of Interest and Clustering Receivers
In this hypothetical situation, a new rail transit line, labeled "new rail line" in Figure D -I, is proposed along a major urban street with commercial land use. A residential area is located adjacent to the commercial strip, located approximately one-half block from the proposed transit alignment. A major arterial, labeled "highway," crosses the alignment.
Cluster Receivers Along the Primary Project Source
Primary Project Source
The primary project source in this example is the new rail line. Boundaries are first drawn at distances of 0 ft from the right -of- way line (edge of the street in this example), 50 ft, 100 ft, 200 ft, 400 ft, and 800 ft, (Figure D-1).
Distances are labeled at the top of the figure.
This is proposed to be a constant speed section of track, so there are no changes in boundaries due to changes in operations along the corridor. Moreover, no other project sources are shown here, but if there had been a station with a parking lot, lines would have been drawn enveloping the station site at the specified distances from the property line.
Rows of Buildings Parallel to the Transit Corridor
This example includes rows of buildings parallel to the transit corridor. The first set of boundary lines satisfies the requirement that cluster boundaries fall between rows I and 2, and between rows 2 and 3, but there is no line between rows 4 and 5. Consequently, a cluster boundary labeled "R" at the top of the figure has been drawn between the 4th and 5th row of buildings.
Cluster Receivers Along the Primary Project Source
The roadway arterial (labeled "highway") is the only major source of ambient noise shown.
Cluster boundaries are drawn at 0 ft, l 00 ft, 200 ft and 500 ft from the near edge of the roadway on both sides.
These lines are shown with distances labeled at the side of the figure.
Select a Representative Receiver from Each Cluster
Representative receivers are shown as filled circles in Figure D -I. Note that the receivers labeled with "REC" are primarily for use in Appendix E.
Locate receiver, "REC 3". Note that this cluster is located at the outer edge of influence from the major source ("highway") where local street traffic is the dominant source for ambient noise (in practice, this would be verified by a measurement).
"REC 3" is chosen to represent this cluster because it is among the houses closest to the proposed project source in this cluster and it is in the middle of the block affected by the dominant local street. Ambient noise levels at one end of the cluster may be influenced more by the highway and the other end may be affected more by the cross street, but the majority of the cluster would be represented by receiver site "REC 3." FEDERAL TRANSIT ADMINISTRATION 223
r RECEIVERS OF INTEREST
CLUSTER BOUNDARIES
ROADWAY (AMBIENT)
RAIL (PROJECT)
AEC N RECEIVER EXAMPLE
CLUSTER EXAMPLE
SCALE IN FEET
FEDERAL TRANSIT ADMINISTRATION 224
Appendix E: Determining Existing Noise
Different options of determining existing noise, including full measurement, computation from partial measurements, and tabular look -up, are described in Section 4.5, Step 5. This appendix provides additional details associated with each method and examples of when each method could be used.
Additional details on the methods for estimating existing noise are provided below:
Option I: Leq(Ihr) measurement (non-residential) — Full one -hour measurements are recommended to determine existing noise for non-residential receivers of interest. These measurements are preferred over all other options and will accurately represent the Leq(Ihr). The following procedures apply to these full -duration measurements:
■ Measure Leq(Ihr) at the receiver of interest during a typical hour of use on two non -successive days. Choose the hour in which maximum project activity will occur. The Leq(Ihr) will be accurately represented using this method. Typically, measuring between noon Monday and noon Friday is recommended, but weekend days may be more appropriate for places of worship. ■ Position the measurement microphone for all sites as shown in Figure 4-19, considering relative orientation of project and ambient sources. Position the microphone in a location that is somewhat shielded from the ambient source to measure the ambient noise at these locations at the quietest area on the property.
■ Conduct all measurements in accordance with good engineering practice.
Option 2: Ldn measurement (residential) — Full 24 -hour measurements are recommended to determine ambient noise for residential receivers of interest. These measurements are preferred over all other options and will accurately represent the Ldn• The following procedures apply to these full - duration measurements:
■ Measure a full 24 -hour Ldn at the receiver of interest for a single weekday (generally between noon Monday and noon Friday).
■ Position the measurement microphone for all sites as shown in Figure 4-I9 considering relative orientation of project and ambient sources. Position the microphone in a location that is somewhat shielded from the ambient source to measure the ambient noise at these locations at the quietest area on the property.
■ Conduct all measurements in accordance with good engineering practice.
Option 3: La„ computation of Ldn from 3 partial Leq(Ihr) measurements (residential) — An alternative way to determine Ldn is to measure Leq(Ihr) for three typical hours of the day, then compute the Ldn from these three Leq(Ihr) measurements. This method is less precise than its full -duration measurement. The following procedures apply to this partial -duration measurement method for Ldn:
■ Measure the Leq(Ihr) during each of the following time periods:
• During peak -hour roadway traffic
▪ Midday, between the morning and afternoon roadway -traffic peak hours ▪ During late night between midnight and 5 a.m.
■ Position the measurement microphone for all sites as shown in Figure 4-I9 considering relative orientation of project and ambient sources. Position the microphone in a location that is somewhat shielded from the ambient source to measure the ambient noise at these locations at the quietest area on the property.
■ Conduct all measurements in accordance with good engineering practice. ■ Compute the Ldn using the equation below
FEDERAL TRANSIT ADMINISTRATION 225
Leq.peakhour•-2 Leq. midday -2 Leq.latenight+8 Eq. E- I Ldn 101og(3 x 10 10 + 12 x 10 10 + 9 x 10 10 ) — 13.8
The resulting Ldn will be slightly underestimated due to the adjustment to the measured levels in these equations. This underestimation is intended to compensate for the reduced precision of the computed Ldn. If using this method, a minimum time duration of one hour should be used for each measurement period in computing an Ldn.
Option 4: Computation of Lan from I partial Leq(Ihr) measurement (residential) — Lan can also be determined by measuring Leq(Ihr) for one hour of the day, and then computing Ldn from the Leq( Ihr)• This method is less precise than computing Ldn from 3 Leg(' ht-) measurements. This method may be useful for projects with are many sites assessed by the General Noise Assessment. This method may also be appropriate when determining if a particular receiver of interest represents a cluster in a Detailed Noise Analysis. The following procedures apply to this partial -duration measurement option for Ldn:
■ Measure the Leq(Ihr) for the loudest hour of project -related activity during hours of noise sensitivity. If this hour is not selected, other hours may be used with the understanding that the estimate is less precise.
■ Position the measurement microphone for all sites as shown in Figure 4-I9, considering relative orientation of project and ambient sources. Position the microphone in a location that is somewhat shielded from the ambient source to measure the ambient noise at these locations at the quietest area on the property.
■ Conduct all measurements in accordance with good engineering practice. ■ Convert the measured hourly Leq(Ihr) to Ldn with the appropriate equation below.
For measurements between 7 a.m. and 7 p.m.:
Ldn s Leq — 2
For measurements between 7 p.m. and 10 p.m.:
Ldn Leq + 3
For measurements between I0 p.m. and 7 a.m.:
Ldn Leq + 8
Eq. E-2
Eq. E-3
Eq. E-4
The resulting Ldn will be moderately underestimated due to the use of the adjustment constants in these equations. This underestimation is intended to compensate for the reduced precision of the computed Ldn. If using this method, a minimum time duration of one hour should be used for each measurement period in computing an Ldn.
Option 5: Computation of Leg('hr)or Ldn from Leg('hr)or Ldn of a comparable site (all land uses) — Computing Leq(Ihr) or Ldn from the Leq(Ihr) or Ldn of a comparable site where the ambient noise is dominated by the same source that is comparable in precision to Option 4. This method can be used to characterize noise in several neighborhoods by using a single representative receiver. It is critical that the measurement site has a similar noise environment to all areas represented. If measurements made by others are available and the sites are equivalent, the existing measurements can be used to reduce the amount of project noise monitoring. The following procedures apply to this method of determining of ambient noise:
■ Choose another receiver that is comparable to the receiver (CompRec) of interest with the following:
The same source of dominant ambient noise
FEDERAL TRANSIT ADMINISTRATION 226
• The ambient level of the comparable receiver was measured according to Option I or Option 2 above
• The ambient measurement at the comparable receiver was made in direct view of the major source of ambient noise, unshielded by noise barriers, terrain, rows of buildings, or dense tree zones
• Determine the following from a plan or aerial photograph:
• The distance (DCompRec) from the comparable receiver to the near edge of the ambient source
• The distance (DRec) from this receiver of interest to the near edge of the ambient source • Determine the number of rows of buildings (N) that intervene between the receiver of interest and the ambient source.
• Compute the ambient level at the receiver of interest (Rec) with the appropriate equation below
If roadway sources dominate:
DRec
LRec LCompRec — 151og( ) 3N
DCompRec
If other sources dominate:
DRec
LRec LcompRec — 251og( ) 3N
DCompRec
Eq. E-5
Eq. E-6
The resulting LRec will be moderately underestimated. This underestimation is intended to compensate for the reduced precision of the computed Ldn.
Option 6: Estimation of Ldn by table look -up (all land uses) — The least precise way to determine the ambient noise is to estimate the level using a table. A tabular look -up can be used to establish baseline conditions for a General Noise Assessment if a noise measurement cannot be made. This method should not be used for a Detailed Noise Analysis. The following instruction applies to this method of determining of ambient noise:
Estimate either the Leq(Ihr) or the Ldn using Table 4-17 based on distance from major roadways, rail lines, or upon population densities. In general, these tabulated values are substantially underestimated.
The underestimation is intended to compensate for the reduced precision of the estimated ambients.
Examples — Examples of when each method of determining existing noise may be appropriate are provided below using the example from Appendix D. Existing noise at the receivers labeled "REC" in Figure D- I could be estimated as follows:
• Option I: Leq(Ihr) measurement — Existing noise at REC I is due to the highway at the side of this church. Leq(Ihr) can be measured during a typical church hour. • Option 2: Ldn measurement — Existing noise at the residence REC 2 is due to a combination of the highway and local streets. Ldn can be measured for a full 24 -hours. • Option 3: Ldn computation of Ldn from 3 partial Leq(inr> measurements — Existing noise at the residence REC 3 is due to the street in front of this residence. Ldn can be computed from three Leq(Ihr) measurements.
FEDERAL TRANSIT ADMINISTRATION 227
■ Option 4: Computation of Ldn from I partial Leq(Inr) measurement — Existing noise at the residence REC 4 is due to the highway. Because the highway has a predictable diurnal pattern, Ldn can be computed from one Leq(inr> measurement. ■ Option 5: Computation of Ldn from Ldn of a comparable site — Existing noise at the residence REC 5 is due to Kee Street. REC 3 is also affected by local street traffic and is a comparable distance from the highway. Ldn for REC 5 can be computed based on the Ldn at REC-3.
■ Option 6: Estimation of Ldn by table look -up — Existing noise at the residence REC 6 is due to local traffic. Ldn can be estimated by tables based on population density along this corridor.
FEDERAL TRANSIT ADMINISTRATION 228
Appendix F: Computing Source Levels from
Measurements
This appendix contains the procedures for computing source reference levels (SELref) from source measurements in cases where the source reference tables in Section 4.5, Step 2 indicate measurements are preferred, data are not available for the source of interest, or more precise data are required than available in the table.
Close -by source measurements for vehicle passbys may capture either the vehicle's sound exposure level (SEL) or maximum noise level (Lmax). Both metrics can be measured directly by commonly available sound level meters. While the Lmax metric is not used for transit noise impact assessments, it can be used to compute SEL source reference levels. Lmax measurements are often available from transit - equipment manufacturers and some transit system equipment specifications may limit close -by Lmax levels.
Close -by source measurements for stationary sources capture the source's SEL over one source event, where the event duration may be chosen based on measurement convenience. The duration will factor out of the computation when the measured value is converted to reference operating conditions.
This manual does not specify elaborate methods for undertaking the close -by source measurements, but rather, provides general processes. It is required that all measurements conform to good engineering practice, guided by the standards of the American National Standards Institute and other such organizations (27, 28, 29).
This appendix presents information according to noise source as follows:
• Appendix F. I : Highway and rail vehicle passbys for vehicles of the same type • Appendix F.2: Stationary sources
• Appendix F.3: Lmax for single train passbys (for trains of mixed consists) F. I Highway and Rail Vehicle Passbys
This section provides information on appropriate conditions for vehicle passby measurements, instructions on converting measurements made under non -reference conditions to source reference levels, and examples of these computations.
The following conditions are required for vehicle passbys, in addition to good engineering practice:
• Measured vehicles must be representative of project vehicles in all aspects, including representative acceleration and speed conditions for buses. • Track must be relatively free of corrugations and train wheels relatively free of flats, unless these conditions are typical of the proposed project.
I. Road surfaces must be smooth and dry, unless these conditions are typical of the proposed project.
I. Perpendicular distance between the measurement position and the source's centerline must be 100 ft or less.
• Vehicle speed must be 30 mph or greater, unless typical project speeds are less than that. • No noise barriers, terrain, buildings, or dense tree zones may break the lines -of -sight between the source and the measurement position.
FEDERAL TRANSIT ADMINISTRATION 229
When close -by source measurements are made under non -reference conditions, use the instructions below and the equations in Table F- I to convert the measured values to source reference levels. For rail vehicles, measure/convert a group of locomotives or a group of cars separately. This computation requires that all measured vehicles be of the same type. For trains of mixed consists, see Appendix F.3.
SEL measured for a highway -vehicle passby, or a passby of a group of identical rail vehicles • Collect the following input information:
• SELmeas, the measured SEL for the vehicle passby
o N, the consist of the measured group of rail cars or group of locomotives o T, the average throttle setting of the measured diesel -powered locomotive(s) • Smeas, the measured passby speed, in miles per hour
Dmeas, the closest distance between the measurement position and the source, in feet • Compute the Source Reference Level SELref, using Eq. F -I.
L. measured for a passby of a group of identical rail vehicles ■ Collect the following input information:
o Lmax, measured for the group passby
o N, the consist of the measured group of rail cars or group of locomotives o T, the average throttle setting of the measured diesel -powered locomotive(s) o Smeas, the measured passby speed, in miles per hour
o Dmeas, the closest distance between the measurement position and the source, in feet o Lmeas, the total length of the measured group of locomotives or group of rail cars, in feet ■ Compute the Source Reference Level SELref, using either Eq. F-2 or Eq. F-3, as appropriate, for locomotives or rail cars.
Lmax measured for a highway -vehicle passby
• Collect the following input information:
o Lmax, measured for the highway -vehicle passby
o Smeas, the vehicle speed, in miles per hour
o Dmeas, the closest distance between the measurement position and the source, in feet ■ Compute the Source Reference Level, SELref, using Eq. F-4.
FEDERAL TRANSIT ADMINISTRATION 230
Table F -I Conversion to Source Reference Levels at 50 ft - Highway and Rail Sources Measured
Source
Equation
SEL
Vehicle
passby
Smeas Smeas
SELref SELmeas 101og( 101og( Cconsist Cemissions
Eq. F -I
= + +
50 ) +
50 ) +
Lora.
Rail -vehicle
passby,
locomotives
only
SELref LAmax 101og(L s) 101og(D50s) 10log(2 Cconsist
Eq. F-2
= + + 00+
50 +Cemissions + 3.3
Rail -vehicle
passby,
cars only
SELref LAmax 101og(L s) 101og(DS0as) 10log
Eq. F-3
= + + [2 cc + sin(2 a)]
50 +Cconsist + Cemissions + 3.3
Highway -
vehicle
passby
D,
SELref = LAmax + 201og( 0as) + C + 3.3
Cemissions
Eq. F-4
Smeas =
Dmeas =
Cconsist =
Cemission =
s
Emeas =
Leas =
a =
speed of measured vehicle(s), mph
closest distance between measurement position and source, ft 0 for buses and automobiles
—101og(Ncars) for locomotives and rail cars
where N is the number of locomotives or rail cars in the measured group O for T < 6 for locomotives
-2 (T-5) for T ≥ 6
where T is average throttle setting of measured diesel — electric locomotives) mea
s) for
rail cars
—30log(S50
s) for buses
—25log(S50
for automobiles
—38.11og(Smeas50)
event duration
total length of
Lmeas
of measurement, sec
measured group of locomotives or rail cars, ft
), rad
arctan(
2Dmeas
FEDERAL TRANSIT ADMINISTRATION 231
Example F -I Calculate SELref — Locomotives
Computation of SELreffrom SEL Measurement of Fixed -guideway Source SEL was measured for a passby of two diesel -powered locomotives with the following conditions:
SELmeas = 90 dBA
NCars = 2
T =6
Smeas = 55 mph
DmPa = 65 ft
Compute the source reference level using Eq. F -I.
SELref = SELmeas + 101og(\S50 s) + 1010g\(D50as) + Cconsist + Cemissions = 90 + 101og (50 I + 101og 150 I - 101og(2) + (-2(6 — 5)) = 86.5 dBA / \ /
Example F-2 Calculate SELref — Rail Cars
Computation of SELref from Lmax Measurement of Fixed -Guideway Source Lmax was measured for a passby of a 4 -car consist of 70 -ft long rail cars with the following conditions:
Lmax = 90 dBA
Ncars = 4
Smeas = 70 mph
Dmeas = 65 ft
Lmeas = 280 ft
a = 1.14
Compute the source reference level using Eq. F-3.
SELref = LAmax + l0log(L 50 s) + 101og( 50 s) 10 log [2 a + sin(2 a)] + Cconsist + Cemissions + 3.3 65 70
= 90 + lO log( 50 ) + 10log(SO) — lO log [2(1.14) + sin(2(1.14))] — lO log(4) — 301og(5O) + 3.3 = 86.7 dBA
FEDERAL TRANSIT ADMINISTRATION 232
Example F-3 Calculate SELref — Bus
Computation of SELref from Lm Measurement of Highway Vehicle Source Lmax was measured for a bus with the following conditions:
Lmax = 78 dBA
Dmeas = 80 ft
Smeas = 40 mph
Compute the source reference level using Eq. F-4
= Lmax + 201og( 50as) + Cemissions + 3.3
80 40
= 78 + 201og(50) — 251og(50) + 3.3
= 87.8 dBA
F.2 Stationary Sources
This section provides information on appropriate conditions for stationary source measurements, instructions on converting measurements made under non -reference conditions to source reference levels, and an example of this type of computation.
The following conditions are required for stationary sources, in addition to good engineering practice:
• Measured source operations must be representative of project operations in all aspects. • The following ratio must be 2 or less, and the distance to the closest source component must be 200 ft or less.
Distance to the farthest source component
Distance to the closest source component
If both conditions cannot simultaneously be met, separate close -by measurements of individual components of this source must be made, for which these distance conditions can be met. ■ The following ratio must be 2 or less:
Lateral length of the source area
Distance to the closest source component
The lateral length of the source area is measured perpendicular to the general line -of -sight between source and measurement positions.
If this condition cannot be met, then make separate close -by measurements of individual components of this source, for which this condition can be met. • No noise barriers, terrain, buildings, or dense tree zones may break the lines -of -sight between the source and the measurement position.
When close -by source measurements are made under non -reference conditions, use the instructions below and the equation in Table F- 2 to convert the measured values to source reference levels.
FEDERAL TRANSIT ADMINISTRATION 233
SEL was measured for a stationary noise source
• Collect the following input information:
o SELmeas, the measured SEL for the noise source, for whatever source "event" is convenient to measure
o Emeas, the event duration, in seconds
o Dmeas, the closest distance between the measurement position and the source, in feet • Compute the source reference level, SELref using Eq. F- 5.
Table F-2 Conversion to Source Reference Levels at 50 ft - Stationary Sources Measured
Source
Equation
SEL
Stationary
noise source
Emeas Dmeas Eq. F- 5
SELref SELmeas 201og(
101og(3600)
= — +
50 )
Smeas = speed of measured vehicle(s), in miles per hour Emeas = event duration of measurement, in seconds
Dmeas = closest distance between measurement position and source, in feet Example F-4 Calculate SELref — Signal Crossing
Computation of SELref from SEL Measurement of Stationary Source SEL was measured for a signal crossing with the following conditions:
SELmeas = 70 dBA
Emeas = I O sec
Dmeas = 65 ft
Compute the source reference level using Eq. F-5.
SELref = SELmeas — 10log(Emeas Dmeas
3600) + 201og( 50 )
10 65
= 70 - 10log(3600) + 201og(50)
= 97.8 dBA
F.3 Lmax for Single Train Passby
This section provides procedures for the computation of Lmax for a single train passby. This procedure can be used to characterize trains of mixed consists using Lmax. Follow the instructions below. • Collect the following input information:
o SELref, from Section 4.5, specific to both the locomotive type and car type of the train o N,oco, the number of locomotives in the train
o Ncars, the number of cars in the train
o LLoco, the total length of the train's locomotive(s), in feet (or Moto unit length) o Lcars, the total length of the train's set of rail car(s), in feet (or Ncars unit length) • S, the train speed, in miles per hour
▪ D, the closest distance between the receiver of interest and the train, in feet • Use the equations in Table F-3 to compute the following:
o Lmax.iocofor the locomotive(s) using Eq. F-6
FEDERAL TRANSIT ADMINISTRATION 234
° Lmax.cars for the rail car(s) using the Eq. F-7
° Lmax total, the larger Lmax from the locomotives(s) and rail car(s) is the Lmax for the total train passby, see Eq. F- 8.
Table F-3 Conversion to Lmax at the Receiver, for a Single Train Passby Source
Equation
Locomotives
Lmax.Loco locos .g (—)-10log = SEL + 1010 S (-50) g(+ lOlo (2 a) 50 3.3 Eq.
F-6
Rail Cars
Lmax.Rcars = SELRcars + 101og (-50) — 10log (—)+0 101og(2 a + sin(2 cc)) — 3.3
Eq. F-7
Total Train
/
Lmax.totai = maxlLmax.Goco or Lmax.RCarS )
Eq. F-8
L = total length of measured group of locomotive(s) or rail car(s), ft S = vehicle speed, mph
a = arctan (M, rad
D = closest distance between receiver and source, ft
FEDERAL TRANSIT ADMINISTRATION 235
Example F-5 Calculate Lmax — Train Passby
Computation of Lmax for Train Passby
Calculate the Lmax of commuter train at receiver of interest according to the following conditions:
SELref = 92 dBA for locomotives
= 82 dBA for rail cars
NLoco
Ncars = 6
S = 43 miles per hour
D = 125 ft
«locos = 0.27
«cars = 1.03
The locomotive and rail cars each have a unit length (L) of 70 ft.
Determine the total length of the locomotive and rail cars.
Loco = 70 ft
Lars = 420 ft
Compute Lmax for the locomotive using Eq. F-6:
Lmax.Loco
S L
= SELloco + 1/0log\ 50 )-10log (50)
(50) + 101og(2 a) — 3.3
=92+10log1501-10log +101og(2x0.27)-3.3
= 84.0 dBA \\\ /ll
Compute Lmax for the rail cars using Eq. F-7:
Lmax.Rcars
= SELRcars + 10log (50) - 10log (5L0 I + 101og(2 a + sin(2 a)) — 3.3 = 82 + 10log (43)5 — 10log (50) + 101og((2 x 1.03) + sin(2 x 1.03)) — 3.3 = 73.5 dBA
Find the total Lmax for the train passby using Eq. F-8.
Lmax.total = max(Lmax.Loco or Lmax.Rcars )
=84.0 dBA
FEDERAL TRANSIT ADMINISTRATION 236
Appendix G: Non -Standard Modeling Procedures and
Methodology
This manual provides guidance for preparing and reviewing the noise and vibration sections of environmental documents, as well as FTA-approved methods and procedures to determine the level of noise and vibration impact resulting from most federally -funded transit projects. Situations may arise, however, that are not explicitly covered in this manual. Professional judgment may be used to extend the basic methods to cover these cases, when appropriate. It is important to note that each project is unique and must be evaluated on a case -by -case basis. This appendix provides procedures for the use of non-standard noise and vibration modeling procedures and methodologies on public transportation projects.
Submittal Procedure — The procedure for using non-standard modeling procedures and methodology is as follows:
I. The transit project manager should contact the FTA Regional office to discuss the proposed methods and/or data not described in this manual prior to use of the non-standard approach.
2. The non-standard methodology should be documented according to the guidelines below as part of the technical report described in Section 8.2.
Examples of Methods that Require Communication and Documentation — The following noise and vibration analysis methods and data require communication with the FTA Regional office and documentation:
■ Non-standard transit noise and vibration modeling and analysis methods not described in this manual (including non-standard adjustments, computations, and assumptions). This includes modifications to standard FTA noise and vibration methods. ■ Non-standard transit noise and vibration reference data not described in this manual (including measured data, substitution data, data at non-standard reference distances and/or speeds, new transit noise sources, and transit noise sources operating in non-standard conditions). ■ Non-standard transit noise and vibration impact criteria not described in this manual, including the maximum sound pressure level metric.
■ Non-standard methods of evaluating construction noise, including non-standard construction noise impact criteria.
■ Other noise modeling tools besides the FTA Noise Impact Assessment Spreadsheet or Traffic Noise Model (TNM®) for highway noise modeling, such as the development of a finite element method model.
■ Any transit noise and vibration analysis that involves an impact area or noise source that is controversial.
Documentation Guidelines — The use of non-standard noise and vibration analysis methods or data requires the following documentation components in a technical memorandum attached to the environmental document:
■ Background
Briefly describe the transit project for which non -default methods or data are needed. State the dominant noise sources, type of analysis, and the impact criteria. Include any additional relevant information.
FEDERAL TRANSIT ADMINISTRATION 237
• Statement of Benefit
Briefly describe the benefit of the non -default noise and vibration methods or data to the transit project. Describe the appropriateness of the non -default methods or data, as well as why the standard method or data are insufficient or problematic. • Non-standard Data Description
Describe the non-standard noise or vibration data in detail. Include source type, manufacturer, reference conditions (speed, distance, and operational conditions), name of data supplier, and a date associated with data development/measurement. For measured noise or vibration data, provide corresponding data documentation (such as a data measurement or a development report). For substitution data, a comparison between the non-standard data and corresponding standard data should be provided. Furthermore, if outside sources recommend the use of the non-standard data (such as a technical society, a standards organization, or a vehicle manufacturer), references for those recommendations should be included. • Non-standard Methods Description
Describe the non-standard noise or vibration analysis method in detail. This should include a detailed description and derivation of the method (including data used in the development of the method), a description of the usage of the method, and a comparison between the non-standard method and the corresponding standard method in the context of the transit analysis. If the method has been validated against measurement data, a description of that validation analysis should be provided. If the method is derived from another source (such as a different transportation noise or vibration method), provide corresponding documentation for that source. A description of how the method is conservative (for example, estimating the worst - case scenario) or some discussion on the probability of exceeding the predicted level should be provided. Furthermore, if outside sources recommend the use of the non-standard method (such as a technical society or standards organization), references for those recommendations should be included.
• Non-standard Tools Description
Describe in detail any non-standard noise or vibration models that have not been explicitly recommended in this manual. This should include a detailed description of the tool (including data used, the computations implemented in the tool, any modifications or adjustments to the tool or the corresponding data, and the usage of the tool), a description of the validation of the tool (including reference documentation and validation analyses), and a comparison between the non-standard tool and the equivalent standard tool in the context of the transit analysis.
Quantitative comparisons, such as the standard deviation of the non-standard tool and an estimate of the least mean square of differences between the standard and non-standard tools, should be provided and explained. A description of how the method is conservative (for example, estimating the worst -case scenario) or some discussion on the probability of exceeding the predicted level should be provided. If outside sources recommend the use of the non- standard tool (such as a technical society or standards organization), references for those recommendations should be included.
FEDERAL TRANSIT ADMINISTRATION 238
ENDNOTES
Regulations for Implementing the Procedural Provisions of the National Environmental Policy Act, Council on Environmental Quality, 40 CFR parts 1500-1508, 1978.
2 3
4 s
6 7
8 9
Io
I2
13 14
National Environmental Policy Act of 1969, United States Congress, 42 U.S.C §433 I, 1969.
U.S. Department of Transportation, Federal Transit Administration and Federal Highway Administration, "Environmental Impact and Related Procedures," Final Rule, 52 Federal Register 32646-32669, January 2014 (23 CFR part 771).
U.S. Department of Transportation, Federal Transit Administration and Federal Highway Administration, "Planning Assistance and Standards." Final Rule, 58 Federal Register 58064, June 2014 (23 CFR part 450).
U.S. Environmental Protection Agency, "Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety," Report No. 550/9-74-004, Washington DC, March 1974.
Federal Interagency Committee on Urban Noise, "Guidelines for Considering Noise in Land Use Planning and Control," Environmental Protection Agency, the Department of Transportation, the Department of Housing and Urban Development, the Department of Defense, and the Veterans Administration, Washington DC, June 1980.
U.S. Department of Housing and Urban Development, "Environmental Criteria and Standards of the Department of Housing and Urban Development," Final Rule, 44 Federal Register 40861, Washington DC, 12 July 1979 (24 CFR part 51).
American National Standards Institute, "Compatible Land Use With Respect to Noise," Standard S3.23-1980, New York NY, May 1980.
American National Standards Institute, "Quantities and Procedures for Description and Measurement of Environmental Sound," ANSI SI2.9-1998/Part 5, New York. NY, January 1998.
T. J. Schultz, "Noise Rating Criteria for Elevated Rapid Transit Structures," U.S. Department of Transportation, Report No. UMTA-MA-06-0099-79-3, Washington DC, May 1979.
T. J. Schultz, "Synthesis of Social Surveys on Noise Annoyance," Journal of the Acoustical Society of America, Vol. 63, No. 8, August 1978.
S. Fidell, D.S. Barber, T.J. Schultz, "Updating a Dosage -Effect Relationship for the Prevalence of Annoyance Due to General Transportation Noise," Journal of the Acoustical Society of America, Vol. 89, No. I, January 1991.
S. Fidel, "The Schultz Curve 25 -years Later: A Research Perspective," Journal of the Acoustical Society of America, Vol. 1 14, No. 6, Pt. I, December 2003.
"High -Speed Ground Transportation Noise and Vibration Impact Assessment", DOT/FRA/ORD-12/15, U.S.
Department of Transportation Federal Railroad Administration, 2012. 15 National Historic Preservation Act, Section 106; P.L. 89-665, 15 October 1966. 16 The Department of Transportation Act of 1966, Section 4(f); P.L. 89-670, 15 October 1966. 17 U.S. Department of Transportation, Federal Transit Administration and Federal Highway Administration, "Protection of Historic Properties." Final Rule, 65 Federal Register 77725, July 2013 (36 CFR 800).
FEDERAL TRANSIT ADMINISTRATION 239
18 19
20 21
22 23
24 25
26 27
28 29
30 31
32 33
34 "Eligibility and Justification Requirements for Noise Insulation Projects," Program Guidance Letter 12-09, November 2012. https://www.faa.gov/airports/aip/guidance letters/historicalguidance letters/media/aip-pgl- 20 12-09-noise-insulation.pdf.
U.S. Department of Housing and Urban Development, "Environmental Criteria and Standards", Vol. 12, July 979; amended by 49 Federal Register 880, 6 January 1984 (24CFR part 51).
U.S. Department of Transportation, Federal Aviation Administration, "Federal Aviation Regulations Part 150:
Airport Noise Compatibility Planning," January 1981.
U.S. Department of Transportation, Federal Railroad Administration, "Use of Locomotive Horns at Public Highway -Rail Grade Crossings." Final Rule, 70 Federal Register 21844, October 2013 (49 CFR 222).
U.S. Department of Transportation, Federal Highway Administration, "FHWA Traffic Noise Model User's Guide," Report No. FHWA-PD-96-009, Washington, DC, January 1998. Also, "FHWA Traffic Noise Model User's Guide (Version 2.5 Addendum)," April 2004.
J.C. Ross, C.E. Hanson, R.V. Hartz, "Houston Southeast Corridor Environmental Impact Statement BRT Noise and Vibration Assessment," technical memorandum prepared by Harris Miller Miller & Hanson for Metropolitan Transit Authority of Harris County Houston, Texas, September 20, 2005.
U.S. Environmental Protection Agency, "Population Distribution of the United States as a Function of Outdoor Noise Level," Report No. 550/9-74-009, June 1974.
T. M. Johnson, "The Importance of Vehicle Throttle Setting Information for Rail Transit Noise Impact Assessments," Proc. Inter -Noise 2012, New York, NY, August 2012.
U.S. Department of Transportation, Federal Highway Administration, "FHWA Highway Traffic Noise Prediction Model," FHWA-RD-77-108, December 1978.
American National Standards Institute, "American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound, Part 4: Noise Assessment and Prediction of Long-term Community Response," ANSI 12.9-1996, New York, 1996.
C. Harris, "Handbook of Acoustical Measurements and Noise Control." International Organization for Standardization "Acoustics -- Attenuation of sound during propagation outdoors -- Part 2: General method of calculation." ISO 9613-2.
American Society for Testing and Materials, "Standard Guide for Measurement of Outdoor A -weighted Sound Levels," E 1014-84, Philadelphia, 1984.
American National Standards Institute, "Method for the Measurement of Sound Pressure Levels," ANSI S I . 13-1971(R 1976), New York, 1971.
U.S. Department of Transportation, Federal Highway Administration, "Measurement of Highway -Related Noise," FHWA-PD-96-046, May 1996.
J.T. Nelson, "Wheel/Rail Noise Control Manual," Transportation Cooperative Research Report No. 23, Transportation Research Board, Washington, DC, 1997.
"Challenges in Maintaining Quiet Streetcar and Light Rail Systems," Session No. 409, Transportation Research Board Annual Meeting, Washington DC, January 2014.
FEDERAL TRANSIT ADMINISTRATION 240
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
U.S. Department of Transportation, Federal Railroad Administration, "Use of Locomotive Horns at Highway - Rail Grade Crossing," Final Rule, 70 Federal Register 21844, April 27, 2005 (49 CFR 222). "Interim Final Rule for the Use of Locomotive Horns at Highway -Rail Grade Crossings," Federal Railroad Administration, Final Environmental Impact Statement, December 2003.
T.A. Busch, R.E. Nugent, "A Reduced -Scale Railway Noise Barrier's Insertion Loss and Absorption Coefficients: Comparison of Field Measurements and Predictions," Journal of Sound and Vibration, 749-759, October 2003.
U.S. Department of Transportation, Federal Highway Administration, "Highway Noise Barrier Design Package," August 2000.
"High -Speed Ground Transportation Noise and Vibration Impact Assessment," DOT/FRA/ORD-12/15, U.S.
Department of Transportation Federal Railroad Administration, 2012.
American National Standards Institute, "Guide to Evaluation of Human Exposure to Vibration in Buildings," ANSI S3.29 -I983 (ASA 48-1983).
International Organization for Standardization, "Evaluation of Human Exposure to Whole -Body Vibration, Part 2: Continuous and Shock -Induced Vibrations in Buildings (I-80Hz)," ISO -2631-2, 1989.
International Organization for Standardization, "Mechanical Vibration and Shock: Evaluation of Human Exposure to Whole Body Vibration: Part 2 — Vibration in Buildings (I to 80 Hz)," ISO -2631-2, 2003.
J. T. Nelson, H. J. Saurenman, "State -of -the -Art Review: Prediction and Control of Ground -borne Noise and Vibration from Rail Transit Trains," U.S. Department of Transportation, Urban Mass Transportation Administration, Report No. UMTA-MA-06-0049-83-4, DOT-TSC-UMTA-83-3, December 1983.
Y. Tokita, "Vibration Pollution Problems in Japan," Inter -Noise 75, Sendai, Japan, 1975. (pp. 465-472) J. A. Zapfe, H. Saurenman, S. Fidell, "Ground -Borne Noise and Vibration in Buildings Caused by Rail Transit," Transportation Research Board, Final Report for TCRP Project D- 12, December 2009.
J.T. Nelson, H.J. Saurenman, G.P. Wilson, "Handbook of Urban Rail Noise and Vibration Control," prepared under contract to U.S./DOT Transportation Systems Center, Report No. UMTA-MA-06-0099-82-2, February 1982.
International Organization for Standardization, "Mechanical Vibration — Ground -borne Noise and Vibration Arising from Rail Systems," ISO/FDIS 14837-1:2005.
Institute of Environmental Sciences and Technology, "Considerations in Clean Room Design," RR-CC0I2. 3, 2015.
U.S. Department of Transportation, Volpe National Transportation Systems Center, "Vibration Characteristics of the Transrapid TR08 Maglev System," Report No. DOT-VNTSC-FRA-02-06, March 2002.
S. McKenna, "A Study of Build Amplification from Ground -Borne Vibration," Noise -Con 2011, Portland, Oregon, July 25-27, 201 I.
51 American National Standards Institute, "Acoustical Terminology," ANSI S I . I - 1994. 52 J.T. Nelson, H.J. Saurenman, "A Prediction Procedure for Rail Transportation Ground -Borne Noise and Vibration," Transportation Research Record, 1143, August 1988.
FEDERAL TRANSIT ADMINISTRATION 241
53 54
55 56
57 58
59 60
61 62
63 64
65 66
67 68
69 J. T. Nelson, "Tri-Met Track Vibration Isolation Tests," Final Report for Portland Tri-Met, October 1998.
J.T. Nelson, H.J. Saurenman, "Ground -Borne Vibration Tests with MARTA C -Car," report prepared for Metropolitan Atlanta Rapid Transit Authority, November 16, 1981.
H.J. Saurenman, "Preliminary Results of Ground -Borne Vibration Tests with BRRT/Miami Vehicle," technical memorandum prepared for US DOT/Transportation Systems Center, contract DOT-TSC-1796, 8 February1983.
H.J. Saurenman, "Ground -borne Vibration Tests with NFTA Prototype Vehicle at the Transportation Test Center," technical memorandum prepared for Transportation Test Center, Project No. P -83-C-01078, 3 August 1983.
H.J. Saurenman, "Noise and Vibration Tests with Portland Tri-Met Prototype Vehicle at the Transportation Test Center," technical memorandum prepared for Transportation Test Center, Project No. P -83-C-02649, 26 March 1984.
R.A. Carman, D.L. Watry, "Measured Vibration Reduction Performance of Ballast Mat Installation for Light Rail Vehicles on Embedded Track," APTA, 1997 Rapid Transit Conference of the APTA, V. 3 -Way & Structures and Construction (1997-8).
D.A. Towers, "Evaluation of the Ground -Borne Vibration Reduction Properties of Tire Derived Aggregate Installed on the Denver RTD Light Rail System," Harris Miller Miller and Hanson Inc., 2012.
F. E. Richert, J. R. Hall, Vibrations of Soils and Foundations, Prentice -Hall, Inc., Englewood Cliffs, NJ, 1970.
U.S. Environmental Protection Agency, "Noise from Construction Equipment and Operations, Building Equipment and Home Appliances," NTID300.I, 31 December 1971.
Society of Automotive Engineers, "Exterior Sound Level Measurement Procedure for Powered Mobile Construction Equipment," SAE Recommended Practice J88a, 1976.
Society of Automotive Engineers, "Sound Levels for Engine Powered Equipment," SAE Standard J952b, 1976.
U.S. Department of Transportation, Federal Highway Administration, "FHWA Roadway Construction Noise Model User's Guide," FHWA-HEP-05-054, January 2006. Available at http://www.fhwa.dot.gov/environment/noise/construction noise/rcnm/.
E. Thalheimer, "Construction noise control program and mitigation strategy at the Central Artery/Tunnel Project," Noise Control Eng. J. 48(5), September —October 2000, 157-165).
U.S. Department of Transportation, Federal Highway Administration. "Highway Construction Noise Handbook," FHWA-HEP-06-0I5, August 2006.
D.J. Martin, "Ground Vibrations from Impact Pile Driving during Road Construction," Supplementary Report 544, United Kingdom Department of the Environment, Department of Transport, Transport and Road Research Laboratory, 1980.
J.F. Wiss, "Vibrations during Construction Operations,"Journal of Construction Division, Proc.
American Society of Civil Engineers, 100, No. CO3, 239-246, September 1974.
J.F. Wiss, "Damage Effects of Pile Driving Vibrations," Highway Research Record, No. 155, Highway Research Board, 1967.
FEDERAL TRANSIT ADMINISTRATION 242
70 71
72 73
74 75
76 77
D.A. Towers, "Ground -borne Vibration from Slurry Wall Trench Excavation for the Central Artery/Tunnel Project Using Hydromill Technology," Proc. InterNoise 95, Newport Beach, CA, July 1995.
Swiss Consultants for Road Construction Association, "Effects of Vibration on Construction," VSS-SN640-3 I 2a, Zurich, Switzerland, April 1992.
American Public Transportation Association, Public Transportation Factbook, 55th Edition, March 2004.
American National Standards Institute, "Preferred Frequencies, Frequency Levels and Band Numbers for Acoustical Measurements," ANSI S1.6-1984 (R2006).
U.S. Environmental Protection Agency, "Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety," EPA Report No. 550/9-74-004, March 1974.
National Academy of Sciences, "Guidelines for Preparing Environmental Impact Statements on Noise," Report from Committee on Bioacoustics and Biomechanics (CHABA) Working Group 69, February 1977.
American Public Transit Association, "Noise and Vibration," 1981 Guidelines for Design of Rapid Transit Facilities, Section 2.7, 1981.
T.J. Schultz, "Synthesis of Social Surveys on Noise Annoyance,"Journal of the Acoustical Society of America, Vol. 64, No. 2, August 1978, 377-405.
FEDERAL TRANSIT ADMINISTRATION 243
a
U.S. Department of Transportation
Federal Transit Administration
U.S. Department of Transportation
Federal Transit Administration
East Building
1200 New Jersey Avenue, SE
Washington, DC 20590
https://www.transit.dot.gov/about/research-innovation
EXHIBIT E
Conservancy Territory Map
Wear Deception
Canyon
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Indio Hills Paints
RANCHO MIRAGE :.
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CONSERtyyATfON AREAS Edorn HE Conservation Area
Cal .an Conserver., Area Hegrway 11 Wp1G Conservation Area Coaehells Veday Stomveslor Channel and Odle Conte -ocher Area leak, Pelmx Consereakon C� Arm
t'� Desert end Linkage Conservation Area - Indio Hilke.Jrratrua Trio National Park Llama Corea-v.1.n Area Dos Palnea Conserves,. Area - Joshua Tree National Park Conservation Haas IT -I East India Res Cansrration Arse. - leas Canyon Conserva.i. Area J' �J
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aicM Sdw Hate Conaervalion Area
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EXHIBIT F
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COMMERCIAL
Office 112
Neighborhood Commercial 103
General Commercial 233
Community Commercial 342
Resort Hotel 387
Mixed Use (Commercial/Office/Residential) 71
Regional I nterstate Commercial 186
ACREAGE
City Sphere Total
511 511
2,102 2,102
961 961
1,154 801 1,955
206 39 245
95 95
345 345
Sub -Total 5,374 840 6,214
INSTITUTIONAL
Public/Quasi-Public
City Hall
Fire Station
Hospital
School
Library
Post Office
Utility Station
OPEN SPACE
Public Park
Mountain Reserve
Private Open Space
Floodways and Drainage Channels
112
103
233
75 417
387
71 186
Sub -Total 1,435
83 9
4 132
83 10
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83 9
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39 121
10 3
9 Sub -Total 332 39 371
ROW J Right of Way
OVERLAYS*
Senior Overlay
Special Corner
111 West Specific Plan
111 East Specific Plan
Agua Caliente Band of Cahuilla Indians
Sub -Total
55 41 96
5,175 5,175
2,129 181 2,311
332 332
7,691
1,239
222 7,913
27 1,265
16,070
25 8 ac
122 ac
121 ac
248 ac
2,027 ac
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/2142d -
Via Email & U.S. Mail
Mayor Lynn Mallotto ([email protected])
City of Rancho Mirage
69-825 California Highway 111
Rancho Mirage, CA 92270
RE: Ritz Carlton Rancho Mirage - Environmental Assessment Case No. EA21- 0002, General Plan Zoning Map Amendment Case No. GPZMA21-0001, Development Agreement Amendment Case No. DA21-0002, Mayor Modification Case No. MOD21-0004, & Tentative Parcel Map Case Number TPM23-0002 (TPM38768).
Dear Mayor Lynn Mallotto:
I have been a resident for the past six years at the Mirada Estates (and Mirada Villas) community. Mirada Estates, also known as "The Mountain Sanctuary," is located in the Santa Rosa Mountains and is adjacent to the Ritz Carlton Resort. Our neighborhood is a small enclave of custom homes built by owners and developers and was inspired by the natural beauty of 272,000 acres of surrounding pristine wilderness. The residents of my community have selected this neighborhood because of the solitude that exists in our area.
This prized solitude is the one of chief reasons, among others, that I write this letter concerning problems with the below project that that is proposed in the City of Rancho Mirage ("City").
A. The Proposed Project.
I am writing to you concerning the proposed development project at the Ritz -Carlton Rancho Mirage. The proposed project involves construction described as the Ritz -Carlton Residences Rancho Mirage and the Sky Mesa Recreation Center on a 16.3 -acre site located at 68900 Frank Sinatra Drive, Rancho Mirage, CA 92270 ("Project"). The Project will consist of 106 residential suites and hotel villas (totaling approximately 200,474 -square feet), approximately 23,840 -square feet of event space, approximately 6,273 -square feet of restaurant/ commercial space, and approximately 5,510 -square feet of amenity space.
The overall Project site includes an existing hotel that opened as a Ritz -Carlton in 1988.
The Project would also provide a total of 499 vehicle parking spaces.
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
As part of the proposed Project, the developer requested a General Plan Zoning Map Amendment to amend the City's Mountain Reserve (MR) designation for the Project's Sky Mesa Recreational area to Resort Hotel (Rs -H) on approximately 3.88 acres.
B. The City's Analysis of the Project.
In March 2024, the City released the first Initial study result of the Project. That study resulted in a recommendation to adopt a Mitigated Negative Declaration (MND) for the Project. In July 2024, the City released a Recirculated Initial Study / Mitigated Negative Declaration ("RMND") for the Project. Thereafter, the City issued its December 2024 Final Initial Study / Mitigated Negative Declaration ("FMND") for the Project.
C. Planning Commission Approval of Project.
On January 9, 2025, as party of the proposed Project, the City's Planning Commission considered the following requests from the developer of the Project:
(1) General Plan Zoning Map Amendment to amend the Mountain Reserve (MR) designation for the project's Sky Mesa Recreational area to Resort Hotel (Rs -H) on approximately 3.88 acres (APNs: 689-020-012 & 689-020-014). (2) A Tentative Parcel Map (TPM38768) to establish three parcels (excluding Sky Mesa area) with Parcel 3 of the map containing condo units (Ritz Carlton residences).
(3) Lastly, a 10th Amendment to the existing Development Agreement with Newage Rancho Mirage, LLC (the "10th Amendment") is proposed. Please note that the proposed project (excluding Sky Mesa) is a modification to the originally approved 2006 project entitlements that included residential villas and condominiums.
It is my understanding that the City's Planning Commission previously voted on January 9, 2025, to recommend that this Project move forward and approved the following resolutions and actions:
(1) A resolution approving the mitigation monitoring and reporting program and mitigated negative declaration (sch# 2024030267) for the Project based on environmental assessment case no. EA21- 0002.
(2) A resolution approving general plan zoning map amendment (GPZMA21- 0001), tentative parcel map case no.TPM23- 0002, and major modification case no.
MOD21- 0004.
(3) And ordinance approving development agreement amendment (DA21-0002).
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
D. Problems with the Project.
I am concerned that the City's Planning Commission has approved this Project without addressing numerous problems that will arise with the Project. Before I address those problems, I want to make it abundantly clear that I am not opposed the Project. The Ritz - Carlton has been a wonderful neighbor. I am not opposed to principal of development at all. However, there are a number of issues that I think the City, and the developer, need to address concerning the Project before it proceeds and that is the purpose of this letter.
The proposed Project will significantly impact my neighborhood. In particular, I am deeply concerned about the environmental and infrastructural impacts this Project may have on our neighborhood. I am concerned about this Project moving forward in the follow areas:
(1) Construction phase of the Project and impact on Frank Sinatra Drive; (2) Pedestrian traffic on Frank Sinatra Drive; and
(3) Construction noise; and,
(4) The Project buildings will obstruct resident's views.
I will address each of these points further below.
(1) CONSTRUCTION PHASE OF THE PROJECT AND IMPACT ON FRANK
SINATRA DRIVE
One of the primary problems with the Project will be the increased construction activity that will arise as a result of the construction necessary to bring about this enormous Project into fruition. Since Frank Sinatra Drive will be the main arterial for construction traffic into the Project, traffic will be enormously and negatively impacted in that area. This construction traffic will impact my neighborhood greatly since the visitor numbers are likely to significantly affect ingress and egress via Frank Sinatra Drive'. The chief entry point to the Project will be Frank Sinatra Drive. As this street is shared by both the existing Ritz - Carlton, and my neighborhood, this additional stress on that artery would overload its capabilities. This thoroughfare is crucial for daily commutes and, more importantly, for emergency vehicle access. Many of the residents in my community are elderly and rely on prompt emergency services. Obstructions or delays on this route could have serious consequences.
To address the above concerns, I would propose that the paved service road located behind the Ritz -Carlton be expanded and utilized for all construction -related activities. It is unused currently, and leads directly to the area where the planned Project will be built.
This would include the transportation of heavy equipment, steel girders, concrete, ' Frank Sinatra drive is an east west major collector running through the City. Most of Frank Sinatra drive is constructed to its ultimate design standards with 100 foot right of way. However, Frank Sinatra drive, West of Hwy 111, is designed as a two-lane roadway in the general plan.
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
materials, and construction personnel. By diverting construction traffic away from Frank Sinatra Drive, construction on the Project can proceed but residents and emergency vehicles can retain uninterrupted access to our community. Additionally, this proposed solution would help to minimize noise, dust, and debris in residential areas, preserving the peaceful environment we value. Finally, this solution would decrease the risk of accidents or delays associated with increased traffic on Frank Sinatra Drive.
There are additionally other means to address the above concerns as follows:
• Minimize unnecessary vehicular and machinery activities.
Require contractors to assemble a comprehensive inventory list (Le., make, model, engine year, horsepower, emission rates) of all heavy-duty off -road (portable and mobile) equipment (50 horsepower and greater) that could be used an aggregate of 40 or more hours for the construction project. • Ensure all construction equipment is properly tuned and maintained • Minimizing idling time to 5 minutes or beyond regulatory requirements — saves fuel and reduces emissions.
• Develop a traffic plan to minimize community impacts because of traffic flow interference from construction activities. The plan may include advance public notice of routing, use of public transportation, and satellite parking areas with a shuttle service. Schedule operations affecting traffic for off-peak hours.
Minimize obstruction of through- traffic lanes. Provide a flag person to guide traffic properly and ensure safety at construction sites. Project sponsors should consider developing a goal for the minimization of community impacts. (2) PEDESTRIAN TRAFFIC ON FRANK SINATRA DRIVE
I am very concerned about pedestrian traffic coming up Frank Sinatra Road. As you undoubtedly know, there are no sidewalks that frame Frank Sinatra Road from Highway 111 to the Ritz -Carlton. Despite the absence of sidewalks on that artery, presently there are numerous pedestrians that utilize the road itself to walk and down its length. These pedestrians are often hotel guests unfamiliar with the dangers that await them down the circuitous and steep decline of the road in that area. This foot traffic is guaranteed to increase with the construction of the Project since more residents/visitors will translate to more pedestrians along Frank Sinatra Drive. This increased pedestrian traffic will, then, predictably result in more injuries and accidents in this area. I do not believe that the City, nor the applicant for the Project, has properly analyzed, let alone address, this serious safety concern.
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
To address this concern, it is urged that a protected pedestrian sidewalk be constructed on either side of Frank Sinatra Drive.
(3) CONSTRUCTION NOISE
The construction of this Project will take place over months and years. The construction phase then will introduce substantial noise, dust, debris, and general disruption into the surrounding area which threaten the tranquility and environmental quality that residents currently enjoy.
In correspondence addressing problems with the Project, dated January 9, 2025, the group "Californians Allied for a Responsible Economy" ("CARE"), noted that City's analysis underestimates construction noise impacts for the Project. In that letter (p. 2), CARE noted that "[d]ue to the proximity of residences to the Project site, construction and operational noise impacts would also be significant. Construction noise would increase ambient noise levels by over 20 decibels, which the City acknowledges would be a significant impact2.
The problems with construction noise were also extensively highlighted by the letter submitted by 28 -page letter from Mitchell M. Tsai law firm, submitted on behalf of the Western States Regional Council of Carpenters ("WSRCC"). In that letter (at p. 19-21), WSRCC focused on problems with the City's analysis of ambient noise problems with the Project and its utilization of improper data to analyze the noise problems at the Project:
Meanwhile, as I understand it, no noise measurements have been taken along the southern border of the two parcels on the Project site designated for the resort villa development identified as the Ritz -Carlton Residences (APN 6308932-06- and 630893-208) which are directly adjacent to numerous private residences. Thus, the FMND has inexplicably declined to measure the ambient noise levels in the area adjacent to the most sensitive uses abutting the Project area, namely, numerous private residences. (Id.) Based on the current land -uses proximate to this sensitive residential area, it is exceedingly likely that this zone at the southern edge of the proposed Project site would have the lowest ambient noise levels of any Project -adjacent area.
In spite of these facts, however, the FMND continues to inaccurately claim that " The long-term noise level measurements were positioned as close to 2 And during operations, stationary equipment Tike HVAC systems would exceed the 45 decibel nighttime noise standards at the nearby residences." CARE highlighted evidence (at p. 6) that the highest construction noise would be 69.9 dBA, the Final IS/MND elsewhere states that the composite source noise level at 50 feet varies between 76.2 and 84.4 dBA.
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
the nearest sensitive receiver locations as possible to assess the existing ambient hourly noise levels surrounding the project site." (FMND at p. 145.) The City's continuing failure and refusal to update the Project's noise studies to address these deficiencies is glaring, and the City's responses to comments fail to address the lack of study of the ambient noise levels at positions closest to the Project's nearby sensitive receptors. (See FMND, Appendix J, Responses to Comments, Response to Comment Letter O1, pp.
RTC -839 - 840.) The City cannot be permitted to shirk the performance of proper environmental analysis for the Project in order to conceal the Project's true impacts.
The FMND has then continued to utilize this faulty and incomplete ambient noise survey data to conclude that there will be no significant impact to the surrounding sensitive receptors from the Project's construction noise. The FMND adopted the Criteria for Recommended Standard: Occupational Noise Exposure prepared by the National Institute for Occupational Safety and Health (NIOSH) as the threshold for whether the anticipated construction noise from the Project will have a significant impact upon the Project nearby sensitive receptors. (FMND at p. 149.) The FMND then concludes that the threshold of 85 dBA Leq qualifies as an " acceptable threshold for construction noise at the nearby sensitive receiver locations," and the noise sensitive residential receiver locations will satisfy the 85 dBA Leq significance threshold," such that the Project will have a less than significant construction noise impact upon the sensitive receiver locations. (Id.) WSRCC reiterates that the NIOSH Occupational Noise Exposure standard has no proper place in evaluating the significance of construction noise impacts on nearby sensitive receptors. Rather, the NIOSH standard is aimed at protecting workers/laborers exposed to noise during the course job duties and preventing occupational harm/injury from occurring. It has no bearing upon external noise levels that would be suitable for maintaining the quiet enjoyment of an individual's private property. In that regard, the selection of 85 dBA Leq by the MND, RMND, and now the FMND as an acceptable threshold of significant construction noise impact is not only arbitrary, but it is also entirely unfounded.
The Federal Transit Administration's ("FTA") Transit Noise and Vibration Impact Assessment provides superior source of federal regulatory authority regarding a project's noise impacts and their significance on sensitive receptors. To that end, the FTA guidance on noise level impacts notes that the impacts should be assessed as a function of their increase over existing noise exposure, and that any noise increase of 15 dBA or greater for a residence is considered a " severe impact." (See Exhibit D-FTA Transit Noise and Vibration Impact Assessment, pp. 17-18, 23-31.) The MND/RMND/FMND arbitrarily elected to use the inapplicable NIOSH
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
standard to assess the noise impacts of the Project, without considering the widely accepted guidance on noise impacts put forth by the FTA. This added lack of study and analysis enlarges the scope of the fair argument that the Project may have significant noise impacts on the environment.
Applying the FTA noise impact guidance, WSRCC maintains that the FMND's dBA estimates for anticipated Project -attributed construction noise exposure levels at the inadequately selected survey locations ( L1, L2, and L3) still have the potential to exceed an FTA guidance - based threshold of "severe impact" and thereby cause a significant noise impact in the surrounding environment. (FMND at p. 146, Table 13-2; compare FMND at p. 149, Table 13-3.) Indeed, comparison of the dBA values set forth in Table 12-3 and Table 13-3 confirm that the construction noise levels nearest to the vast majority of the Project's adjacent sensitive residential receptors are anticipated to increase by greater than 15 dBA from the ambient levels detected at L1, L2, and L3. (See id.) Put simply, after applying the FTA guidance to the FMND noise threshold," such that the Project will have a less than significant construction noise impact upon the sensitive receiver locations. (Id.)
One does not need to be a scientist schooled in the above to know that there will be a large amount of construction noise attendant to the construction of the Project that is deleterious to the environment of my community. Because construction noise will undoubtedly exceed a significant threshold, it must be mitigated in some reasonable manner.
Construction work on the Project is also to occur (is also exempt from provisions in the City's noise code), within allowable hours of 7 am to 7 pm (and is prohibited to occur on Sundays and holidays.) To address this concern, it is urged that the City restrict the hours of construction by limiting the window under which construction is permitted by allowing construction to begin at 8:00 am, and end at 6:00 pm.
(4) THE PROJECT'S BUILDINGS WILL OBSTRUCT THE VIEW OF RESIDENTS...
Finally, I am concerned about the Project because construction of proposed buildings will undoubtedly impact the views of numerous residents in my community. In particular, I am concerned about the view of residents of dwellings located at the north-east corner of Mirada Estates along Mirada Circle and Grand View Court. It does not appear that the City property analyzed the impact of the Project on the view of those homeowners. If indeed, those homeowner's view are negatively impacted, then the City, and the applicant for the Project, should (1) make those impacts clear; (2) if so negatively impacted, determine whether or not alternative exists that would allay those impacts/obstructed views.
CONCLUSION
Mayor Weill and Honorable Members of the City Council
City of Rancho Mirage
I want to again make clear that I not opposed to the Project, only that portions of the Project, and its impacts, need to be addressed as set forth above. Due to the Project's potentially significant impact on the areas described above, I urge the City not to recommend approval of the Project until the problems and impacts outlined above are properly addressed and are fully mitigated.
Sincerely,
l
CC: Isaiah Hagerman, City Manager ([email protected])