Environmental Noise Test for transit project

METRO ROLLING STOCK (TRAIN) NOISE PERIODIC TEST PROCEDURE

Mumbai Metro One Pvt Ltd

Amendment Record

Rev No

Amended Date

Amended By

Section/page Amended

Amended details

Document Prepared By Reviewed By Approved ByDateName Jayakumar Vikas Sardana Vikas SardanaDesignation Assistant Manager General Manager, Rolling Stock. General Manager, Rolling Stock.

Signature

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Mumbai Metro One Pvt LtdDivision Rolling StockSystem/Equipment Train Document No RS-MN-Document Type Routine/Periodic Test ProcedureRevision 00Page No 1 of 22Name of Document: Periodic Test Procedure of Noise Test

1. Title

Routine/Periodic test procure of Noise Test.

2. Purpose of Test Procedure

The Test procedure for measurement of exterior noise of Rolling Stock, when in standstill and during motion of vehicle, Noise monitoring test shall be conducted after an interval of time or after modification of Rolling stock.

The objective of the test is to check and confirm acoustic comfort level as per ISO 3095 and as per “The Noise Pollution Rules, 2000”.

3. Reference Documents

ISO 3095: Railway Applications–Acoustics–Measurement of Noise emitted by Rail bound vehicles.

The Noise Pollution (Regulation and Control) Rules, 2000. Ministry of Environment & Forests.

IEC 61672-1: Electroacoustics – Sound level meters

FTA Noise and Vibration Manual

4. Definitions & Abbreviations

4.1. Definitions:

4.1.1. Monitoring Test: The Test performed to check, whether the noise of vehicle changed after a Period (eg: 1year or 6 months) of time or after modification of Rolling Stock.

4.1.2. Roughness (r): Root mean square (RMS) value of the amplitude variation of the running surface of a rail in the direction of motion measured over a rail length.

4.1.3. Sound Pressure p(t): Root mean square (RMS) value of a fluctuating pressure superimposed on the static atmospheric pressure measured over a certain time period, expressed in Pa.

4.1.4. Phon (dB): Phon is a unit of measurement of loudness. If 1dB of sound is measured at 1000Hz (reference frequency), then it is said to have a loudness of 1 phon.

4.1.5. A-Weighing dB(A): The A-Weighting filter covers the full audio range of 20Hz to 20kHz and the shape is similar to the response of human hear at the lower level.A-Weighted sound level measurement is commonly used for measurement of environmental noise and industrial noise, as well as for potential hearing damage and other noise effect of all sounds. The measurement made using ‘A’ weighting are usually shown in LpA dB(A).

LpA = 10lg (pA (t)/po)2

LpA : A-weighted sound pressure level in dBpA(t) : RMS A-weighted sound pressure in Papo : Reference sound pressure; po = 20 µPa

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4.1.6. A-weighted equivalent continuous sound pressure level: Equivalent (average) sound pressure level in dB for a period of time.

LpAeq.T : A-weighted equivalent continuous sound pressure level in dBpA(t) : RMS A-weighted sound pressure in Papo : Reference sound pressure; po = 20 µPaT : Time interval in sec.

4.1.7. A-weighted equivalent continuous sound pressure level: Equivalent (average) sound pressure level in dB for a period of time.

LpAeq.Tp : A-weighted equivalent continuous sound pressure level on time pass by time in dB.pA(t) : RMS A-weighted sound pressure in Papo : Reference sound pressure; po = 20 µPaTp=T2-T1 : Time interval in sec.

4.2. Abbreviations:

dB Decibel

R Roughness

P(t) RMS sound pressure

Lp Sound pressure level

LpA A-weighted sound pressure level

Pa Pascal

S Second

T Time in second

5. Safety Precautions:

6. Tools required:

6.1 Microphone / A-weighted sound measurement device.

6.2 Measurement Tape, 20 meter.

7. Responsibility: Rolling Stock Engineer

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8. Procedure: Measurement of Exterior Noise

Vehicle (Train) noise is measured in following types to check and confirm the acoustic noise level limit, when the Train is at stationary and running.

1. Noise level measurement of Stationary Train

2. Noise level measurement of Running Train at constant speed.

3. Environmental Noise measurement and Noise impact analysis.

8.1 Noise level measurement of stationary Train.

8.1.1 Measurement position:

For stationary Train, the measurement points as shown below. Each car Noise is measured from center of the car, 7.5 meter from tract center line and 1.2 meter above the track.

8.1.2 Test Train Condition: The vehicle shall be unoccupied or person in the vehicle shall be restricted to

minimum During measurement doors of the vehicle shall be kept in closed condition. The auxiliary equipment in the Train shall be operated simultaneously at their

maximum capacity.

8.1.3 Track and environmental condition The test track should be an open section, There should not be any large sound reflecting objects such as tall buildings,

mountains, bridges etc. Any Sound or person shall be avoided between microphone (sound measuring

device), that influence measured sound pressure level. Measurement shall be made if the wind speed is below 5m/s and there is no rain

falling

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8.1.4 Back ground sound pressure level

For monitoring test “Difference of A-Weighted sound pressure level” shall be at least 5dB above.

If the difference in sound level is less than 10dB the reading obtained shall be corrected as per below table.

Difference of A-Weighted sound pressure level dB

Correction to be added to A-Weighted sound pressure level obtained from the vehicle in presence of back ground noise dB.

> 10 06 to 9 -1

5 -2

8.1.5 Test Procedure Microphone should be placed in exterior at the center of the car, 7.5m from track

center and 1.2m above the rail top. Measurement period shall be T=20sec as per ISO 3095. The maximum time interval can be reduced to 5sec, but it should be justified in test report.

8.1.6 Evaluated quantity Equivalent continuous noise level (LpAeqT, mentioned in clause 4.1.6) measured

over an observation period of 5sec as specified in ISO 3095:2005.

8.1.7 Test report

Nature of the test

Train No used for Test

Location

Track typeEnvironmental condition, such as wind speed, temperature and humidity.

Wind Speed : Temperature :Humidity :

Test site, track and meteorological conditionMeasurement Equipment type and calibration data.

Back ground noise levelAuxiliary equipment and its operating condition

Loading of the vehicle

Sensor position

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Difference of A-Weighted sound pressure level

Noise measured from the vehicle in presence of back ground noise

A-weighted back ground sound pressure alone= -

Measuring point DT-1 M-1 M-2 DT-2

1 st

2 nd

3rd

Average

8.2 Noise level measurement of Running Train at constant speed

8.2.1 Measurement position: Microphone should be placed 7.5 meter from tract center line and 1.2 meter above

the track.

8.2.2 Test Train Condition: The vehicle shall be unoccupied or unloaded, no of person in the vehicle shall be

restricted to minimum The wheels of the Test train should not have any flats, burning or any other damage,

which will generate abnormal noise. During measurement doors of the vehicle shall be kept in closed condition. The auxiliary equipment in the Train shall be operated simultaneously at their

maximum capacity.

8.2.3 Track and environmental condition The track should be an open section and straight. Roughness of the rail of the track should be less than the value specified in

ISO3381:2005 The permissible radius of curvature of noise test should be greater than R=3000m

and level gradient. There should not be any large sound reflecting objects such as tall buildings,

mountains, bridges etc. Any Sound source or person shall be avoided between microphone (sound measuring

device), that influence measured sound pressure level. Measurement shall be made if the wind speed is below 5m/s and there is no rain

falling

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8.2.4 Back ground sound pressure level

For monitoring test “Difference of A-Weighted sound pressure level” shall be at least 5dB above.

If the difference in sound level is less than 10dB the reading obtained shall be corrected as per below table.

Difference of A-Weighted sound pressure level dB

Correction to be added to A-Weighted sound pressure level obtained from the vehicle in presence of back ground noise dB.

> 10 06 to 9 -1

5 -2

8.2.5 Test Procedure Over the measurement section of the track, the train should run at the chosen constant

speed or at maximum speed 80kmph, the speed should be stabilized within ±5%. The measurement time interval T will begin, when the front of the train is passing the

microphone and will end when rear of the vehicle is clearing (passing) the microphone.

8.2.6 Evaluated quantity

Evaluation quantity is the equivalent continuous noise level (LAeq)

8.2.7 Test report

Nature of the test

Train No used for Test

Location

Track typeEnvironmental condition, such as wind speed, temperature and humidity.

Wind Speed : Temperature :Humidity :

Test site, track and meteorological conditionMeasurement Equipment type and calibration data.

Back ground noise levelAuxiliary equipment and its operating condition

Loading of the vehicle

Sensor position

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Difference of A-Weighted sound pressure level

Noise measured from the vehicle in presence of back ground noise

A-weighted back ground sound pressure alone= -

Record sheet:

Measuring point

Train Speed Measured value in dB

Ambient/Acoustic noise

Remarks

1 st

2 nd

3rd

4th

5th

6th

Average

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8.3 Assessment of Transit Noise Impact on Environmental Noise Level:

Assessment of Metro Trains Noise impact on Noise sensitive location such as Residential Building, Schools and Hospitals, around Metro viaduct shall be measured and analyzed.

Detail Noise Assessment Test:

1. Screening Procedure.2. General Noise Assessment.3. Detail Noise Analysis.

3.1. Measurement of Noise Exposure level of Metro Trains3.2. Measurement of Existing Noise Exposure level.3.3. Analysis of Measurements and Noise Impact Criteria.

3.3.1. Ldn Calculation of Metro Trains.3.3.2. Project Noise vs. Distance exposure curve.

3.4. Analysis of Noise impact on nearby location and for Mitigation.3.5. Procedure to measure Project Noise and Environmental using NTi –

Audio meter3.6. Project Noise and Environmental Noise Record Sheet.

1. Screening Procedure:

The noise screening procedure is to identify location, where a project may cause noise impact. For screening purposes, all noise-sensitive land uses are considered to be in a single category. If no noise-sensitive land uses are present within a defined area of project noise influence, then no further noise assessment is necessary.

The screening distance shall be taken 350 feet (obstructed) or 700 feet (unobstructed) from Metro viaduct center, where the project Noise reaches almost 50 dBA.

If intervening buildings near to via duct the Screening distance shall be chosen 350 feet. If the location is unobstructed (no large sound absorption materials), then screening distance shall be chosen 700 feet from the center of Metro viaduct.

2. General Assessment:

General assessment shall be consider during planning of new project or modification of existing project. The general assessment based on theoretical values or estimated values. The results are useful to analysis for any mitigation requirement of project.

Actual noise calculation of the project impact on environment shall be analyzed with “Detail Noise Analysis”.

3. Detail Noise Analysis

The detail noise analysis results exact project impact on the existing environment, the detail analysis provides systematic process, from measurement of Nosie level to presentation of report.

3.1. Measurement of Noise Exposure level of Metro Trains

The Noise exposure level of Metro Trains shall be measured from 50 feet from Metro viaduct center and approximately 3.9 feet (1.2 meter) from rail top. Noise exposure level SEL can be directly measured or Leq measured shall be converted to SEL with period of measurement.

SEL (Sound Exposure Level) = LeqA Measured + 10lg (T- Period of Measurement)Rev1 Page 9/21


3.2. Measurement of Existing Noise Exposure level.

Measurement of existing noise on nearby location, where the project noise has been measured. Existing noise shall me measured for a whole day or an hour measurement, depends on the location and environment.

Recommended Microphone position to Measure Existing Noise:

Microphone can be placed on receiver interest, but the position of microphone must record all the environmental noise on average. For example, a highway is running in front of house, if the microphone kept in back side of the house, it will not record actual noise of highway. So detail analysis is required to include all the existing noise on measurement. If the location having fluctuation noise, then measurement shall be taken on two to three location.

Measurement Duration of Existing Noise:

1. Existing Noise Exposure Leq (H) for nonresidential area during Noon hours of the alternative week days.

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2. Measurement of Existing Noise exposure level in Residential area. Full day measurement of Ldn will results exact value of existing noise.

Option -1:

Measure full day noise exposure level Ldn. If the location is exposed with high external noise sources and accurate/actual Existing noise.Measurement shall be taken generally between Noon Monday and Noon Friday.

Option -2:

Measure hourly Leq of three Hours and compute Ldn with three hourly Leq. The measurement is preferable, if the location is exposed to moderate impact. The obtained Ldn will be slightly underestimated, for accurate Existing Noise measurer full day Ldn.

Three Measurement will be taken during “peak hours, midday and late night to early morning”.

Option -3:

Ldn can be obtained with only LeqA one hour existing noise measurement, Ldn obtained will be moderately underestimated.

Measurement between 7 am to 7 pm : Ldn ≈ Leq – 2 Measurement between 7 am to 10 pm : Ldn ≈ Leq + 3 Measurement between 10 pm to 7 am : Ldn ≈ Leq + 8

3.3. Analysis of Measurements and Noise Impact Criteria

3.3.1. Ldn Calculation of Metro Trains.

Calculation of Ldn with measured SEL of Metro Train and operational inputs, such as speed of Train and Train traffic.

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3.3.2. Project Noise vs. Distance exposure curve.

Estimation of project noise exposure at other distance on the receiver interest. “The project noise vs. distance exposure curve” will cover project impact Ldn and Leq from 50 feet to 1000 meter.

D – Distance 50 feet to 1000 feet.G – Ground Factor.

Calculation of Ground factor:

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Ldn or Leq

Example of Project Noise vs. Distance exposure curve:

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3.4. Analysis of Noise impact on nearby location and for Mitigation.

Project Noise exposure and Existing noise exposure were obtained and Noise level impact around the location can be identified with “Project Noise vs. Distance exposure curve”.

Noise Impact Criteria: Reference FTA manual Section 3.1

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Example of Noise impact analysis on nearby location:

Project Noise: Ldn at 50 feet : 65 dBExisting Noise Ldn : 62 dBReceiver interest : 1.2 Meter (3.937 feet) from Rail Top.Ground factor (G) : 0.63Location : Residential Buildings

Project Noise vs. Distance exposure curve:

Project Noise Exposure at Different DistanceImpact of Project Noise at different distance

with Existing Noise exposure: 62 dBAt 50 to 58 feet from viaduct center, Project Noise: > dB Project noise Expose in “Severe Impact”.At 59 to 109 feet from viaduct center, Project Noise: 63.3 dB

Project Noise Exposure in “Moderate Impact”.

After 119 feet from viaduct center, Project Noise: 58.3 dB Project Noise Exposure in “No Impact”.

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Ldn or Leq

Noise Mitigation:

Noise mitigation is to minimize noise pollution and noise impact on the environment. Mitigation as strongly recommended, if the Ldn of Project Noise is more than 65 dB.

As per “The Noise pollution (Regulation and Control) Rules, 2000”, ambient noise should be less then below mentioned value.

Category of Area / Zone

Limits in dB (A) Leq

Day Time Night Time

Industrial Area 75 70

Commercial Area 65 55

Residential Area 55 45

Silence Zone 50 40

Note:

Day Time : 6.00 a.m. to 10.00 p.m.Night Time : 10.00 p.m. to 6.00 a.m.

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Selection of Noise sensitive site

Measurement of Noise exposure level SEL of Metro Train at 50 feet from

Viaduct center.

Convert Measure SEL of Metro Trains into SEL Reference.

Calculate Ldn or Leq (H) with SEL reference and operation Characteristics

of Metro Trains.

Calculate Ldn or Leq (H) with SEL reference and operation Characteristics

of Metro Trains.

Calculate Noise exposure level at the Noise sensitive location with “Estimating Exposure vs Distance in General Noise

Assessment.

Noise Impact Criteria with Calculated project Noise Exposure vs Exiting Noise Exposure.

Noise Impact Level

Mitigation required?

Noise Test Report

NO

YES

Existing Noise Exposure Leq (H) for nonresidential area during Noon hours of the alternative week days.

Measurement of Existing Noise exposure level in Residential area. Full day measurement of Ldn will results exact value of existing noise.

Option -1: Measure full day noise exposure level Ldn. If the location is exposed with high external noise sources.Measurement shall be taken generally between Noon Monday and Noon Friday.Option -2: Measure hourly Leq of three Hours and compute Ldn with three hourly Leq. The obtained Ldn will be slightly underestimated.Three Measurement will be taken during peak hours, midday and late night to early morning. Option -3: Measure only one Leq Hours and compute Ldn.Ldn obtained will be moderately underestimated.Measurement between 7 am to 7 pm : Ldn ≈ Leq – 2Measurement between 7 am to 10 pm : Ldn ≈ Leq + 3Measurement between 10 pm to 7 am : Ldn ≈ Leq + 8

3.5. Procedure to measure Project Noise and Environmental using NTi – Audio meter:

Nti – XL2 audio and acoustic analyzer:

XL2 is an advanced integrating sound level meter designed according to IEC 61672. XL2 is designed to measure sound level of Audio – Acoustic installation (eg: Cinemas), Noise

measurement (eg: Live events, environmental noise), live sound (eg:PA), Broadcast, building acoustics, industrial quality control and aerospace.

Refer XL2 operational manual to operate the device and to measure sound level.

Select the parameter in the meter to measure equivalent acoustic noise in dB (LAeq), Maximum acoustic noise in dB (LAmax), Live acoustic noise in dB.

After settings of parameter, press start/stop button to start Measure acoustic noise for a period of time (Defined or as per requirement) and press again start/stop button to stop measurement.Note the measured values in record sheet and save the file.

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Live acoustic noise in dB

Equivalent acoustic noise in dB (LAeq)

Maximum acoustic noise in dB (LAmax)

Environmental Noise Test Location, Project Noise Measurement and Existing Noise Measurement Record Sheet

Horizontal Distance of Noise level Meter / Microphone placed from the center of track 15.2 Meter

Microphone Vertical height from Rail

Top.

App 1.5 Meter

Temperature: Date

Humidity:

Project Noise Measurement Existing Noise Measurement Location: Location:

First Measurement

Train Set Passing

Actual TimeMeasured Leq or SEL Remarks Start Time

Ldn Measured

Remarks

Approaching 50m, Microphone

Leaving 50m, Microphone

End Time

Second Measurement

Start Time Ldn Measured

Remarks

End Time

Third Measurement

Start Time Ldn Measured

Remarks

End Time

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