noise pollution 140
TRANSCRIPT
Air Transport & Noise Pollution:
Atul K [email protected]
Environmental Engineering LaboratoryDepartment of Civil EngineeringIndian Institute of Technology Delhi
Noise:
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Noise is defined as"unwanted sound”
In contrast to otherenvironmental pollution,noise pollution is special in that Personal and subjective judgment is a big part of recognizing asound as noise pollution or not.
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Noise is everywhere
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Basics of Sound:
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Characteristics of SoundPhysical ParametersSound FieldsMeasurements of sound
Characteristics of Sound -- Amplitude:
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P = Pressure Amplitude..
The higher the amplitude, the
higher the sound pressure
levelPressure Amplitude Pmax = maximum deviation of the pressure from atmospheric pressure
P = Pmax sin(kx-wt)
Characteristics of Sound -- Frequency:
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Frequency f = number of pressure fluctuations per second TheFrequency is related to the period:
f = 1/TFrequency is measured in
Hertz (Hz)1 Hz = 1 cycle per second
Characteristics of Sound -- Wavelength:
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Wavelength λ = The distance required for the wave to repeat itself
Wavelength is related to frequency by the speed of sound: λ = c/flow frequency – long wavelengthhigh frequency – short wavelength
Physical Parameters – Sound Pressure:
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Pressure equation: P = Pmax sin(kx-wt)Displacement equation S = Smax cos(kx-wt)
Pmax = (Bk) Smax
WhereB = Bulk modulous of elasticityk = angular wave numberw = angular frequency
If the velocity of sound = V then B = V2pSo Pmax=(V2pk)Smax = (Vpw)Smax
Physical Parameters – Sound Power:
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Kinetic Energy dK of a differential mass of air (dm = pAdx) propogationg the sound wave is
dK = ½ dm Vs2
dE/dt = 2dK/dt = pAVw^2Smax^2sin^2(kx-wt)Average power over a whole number of wavelengths
Power W = (dE/dt)avg = ½pAVw2Smax2
Physical Parameters – Sound Intensity:
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The Intensity of a sound wave is defined as the average rate at which power is transmitted per unit cross sectional area in the direction of travel.
I = ½(pVw2Smax2)or
I = Pmax2/(2pV)
Outdoor Noise Propagation:
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The Sound Intensity
I = Q (P/4pi r^2) or I = P/SWhere
Q = directivityP = PowerS = area (spherical or non-spherical)
Sound levels
Lp ~ Li = Le + 10 log(Q/r^2) - 11
Indoor Noise Propagation:
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The Sound Intensity
I = Q (W/4pi r2) or I = W/SWhere
Q = directivityP = PowerS = area (spherical or non-spherical)
Sound levels
Lp ~ Li = Le + 10 log (1/4pir2 + 4/R)
Where R = room constant
Measurement of Sound:
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A sound level meter (SLM) or a microphone &data acquisition system is used to measure
sound pressure levels
Sound Pressure Level (Decibels):
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Unit of measurement : DecibelDecibel is logarithmic
Decibel dB = 10 log(x/y)Where x – value of any measure
y = reference value of the same measure
Sound Pressure Level Lp(dB) = 10 log (P^2rms/4x10^-10)Sound Intensity Level Li(dB) = 10 log (I/10^-12) Sound Power Level Lw(dB) = 10 log (W/10^-12)
Some Numbers (SPL):
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• Rustling leaves: - 10db• Whisper: 30 db• Normal speech: 60 db• Television: 70 db• Traffic: 75-80 db• Blow dryer: 85 db• Noisy hall: 85 db
• Classroom: 85 db• Stereo: 90 db• Bagpipes: 90-110 db• Power saw: 100 db• Fire cracker: 115-120 db• Rock concert: 120 db• Gunshot/train/jet: 150 db
Mathematics of decibels:
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Decibels are logarithmic, not linear
Cannot simply add, subtract, or average sound levels
We can only add the ‘intensity values’, ‘power values’or the ‘rms values of pressures’
Two sources with equal sound levels increase soundlevel by 3 dB
Example: 90 dB + 90 dB ≠ 180 dB90 dB + 90 dB = 93 dB
Noise Pollution
Sound that is unpleasant and unwanted by the listener because of its bothersome nature, interference with the perception of wanted sound or its harmful physiological and psychological effects
IndustrialVehicularAircraftOthers
Sound LevelsSound levels are measured in units of pressure
Decibels (dB)—each 10 dB indicates a doubling of sound/noise (logarithmic scale)
Types of Noises
ContinuousNear a busy Interstate highway
IntermittentThe approach to an airport runway with aircraft spaced a few minutes apart
ImpulsiveA fireworks explosion, a thunderclap, a vehicle backfire, or a single truck using “jake brakes”
Impulsive noises are the most disturbing to most peopleTransportation creates all three types
Effects
Health experts argue noise pollution in India is a major cause of heart attacks and other stress related illnesses. Most transportation noise in the US is now well below the pain thresholdNoise is much more a quality of life issue than a human health issue
Sleep disturbance is the most common complaint of people annoyed by noise
Probably has some health implicationsStartle or fear is nextSpeech interference is next
Excessive noise can reduce residential property values
How Noise Affects our Ears :
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Health effects of aircraft noise
High levels of aircraft noise that commonly exist near major commercial airports causes:
High blood pressureHearing lossHeart diseasesImmune deficiencyAsthmaOther stress related problems
Noise Regulation:
AMBIENT NOISE STANDARDS: CENTRAL POLLUTION CONTROL BOARD.S.No. Area LeqdB(A)
Day Time* Night Time**
1 Industrial Area 75 70
2 Commercial Area 65 55
3 Residential Area 55 45
4 Silence Zone*** 50 40
* Day Time -- 0600 hour to 2100 hour (15 hours)
** Night time --2100 hour to 0600 hour (09 hours)
*** Areas upto 100 metres around certain premises like hospitals, educational institutions and courts may be declared as silence zones by the competent authority
The Noise Regulation Rules 2000Section 3 of the Environmental Protection Act of 1986.
LOK SABHASTARRED QUESTION NO 398ON 21.08.2000
NOISE MODELING METHODOLOGY
To evaluate the expected noise levels for future conditions
Since future noise levels cannot be directly measured, it is necessary to simulate the expected future condition through noise modeling.
It is the only way that alternative airspace designs can be compared to one another to identify the relative noise effects for each proposal.
Data Req
General Study Data: NIRS requires general information about the study to perform the noisecalculations. Study area information such as the coordinates of the center of the study, the lengthand width of the study area and the altitude ceiling of the study are necessary inputs. Alsorequired is climatologically data such as average headwind speed, average annual temperatureand average annual pressure. Finally, any special regions within the study area need to beidentified.
IIT DELHI STUDY: Aircraft Operation
Predict the noise levels, in Delhi, due to the airports in the city. Noise levels at IIT were monitored in order to cross reference the predictionsAircraft noise is variable and intermittent. It is not continuous as in the case of road traffic noise. There are peak noise levels when aircrafts are flying overhead, or are taking-off and landing at the airports.
Environmental Conditions
Ground conditions may greatly impact noise propagation
Hard ground (e.g. concrete) has little impactMixed ground (e.g. grass and other vegetation) may attenuate noise to some extentSoft ground will absorb a great deal of noise
Wind either blunts the spread of noise or carries it farther, depending on the wind direction and speed; at short distances, wind effects are minor
Environmental ConditionsTemperature
On clear nights, temperatures may actually be lower near the ground and increase with altitude
This leads to an air inversionSounds are trapped near the surface and noises will carry farther near the surface under such circumstances
High ambient air pressure, cold temperatures, and low relative humidity/no precipitation are the best weather conditions for noise propagation
Airport Runway and Configuration Data:
Information specific to airport in the study. The location of each runway, the elevation of the runway ends, and the length of each runway.
Input data for configuration data includes annual percentage use for each operational configuration for each airport within the study. This data includes annual configuration use for the airports and runways use for each of those configurations.
INPUT
Airport settingsLatitude and longitude of the airport referencepoint (decimal degrees)Runway end-point x, y positions relative to thereference point (feet)Airport elevation (feet MSL)Airport average annual day temperature (degreesFahrenheit)Airport average annual day relative humidity(percent)Airport average annual barometric pressure
Population and Grid Location Data:
Users input population centroid identification, location & population
Flight Event/Track Data:
FLIGHT
FLIGHT EVENT FLIGHT TRACK
•Flight identification,•City-pair•Time•Runway•Airframe/engine type
•Geometry of the fight in series of points
•Latitude, •Longitude•Altitude
Aircraft types & Input Database
Aircraft flight operation type Number of flight operations for each of three time periods (day, evening, and night) during an average annual day
an acoustic database of noise vs. power vs. distance (NPD) values
Assumptions
•No military flights land on the airports.•No cargo planes land on the airports.•All flights (national or international) land on IGI Airport only.•Out of the two existing runways only the one that is used mostoften shall be considered.•Flight schedule for one week is fixed and is repeated everyweek.•The weather conditions in every part of the city are constant.•For one whole flight series (e.g. Boeing 737, Boeing 734,Boeing 738) only one representative aircraft (e.g. Boeing 737)will be considered.
Airport Data
Elevation: ............. 777 Feet / 237 MetersIATA: .................. DELICAO: .................. VIDPLatitude: .............. 28°33' 59" NLongitude: ............. 77°6' 11" ERunway 1 Length: ......12500 Feet / 3810 MetersRunway 2 Length: ....... 9229 Feet / 2813 Meters
Exposure Based Contour (SEL)
Metric → Actual (dB) INM Metrics
Day↓ SEL (dB) PNLTM (dB) LAMAX (dB)
Day 1 78 >80 75-80 75-80
Day 2 72 >80 75-80 75-80
Day 3 71 >80 75-80 75-80
Day 4 79 >80 75-80 75-80
Day 5 72 >80 75-80 75-80
Day 6 73 >80 75-80 75-80
Day 7 76 >80 75-80 75-80
Noise Levels at IIT
Noise levels at the selected locations
Metrics → PNLTM (dB) SEL (dB) LAMAX (dB)
Location ↓
IITD 75-80 >85 75-80
V.VIHA 80-85 >85 80-85
AIMS 70-75 >85 70-75
R.G. 40-45 70-75 30-35
LNAGAR 65-70 >85 70-75
R.M.L. 40-45 70-75 35-40
DU.S.C. 55-60 >85 50-55
R.S.TB. 60-65 >85 55-60
C.P. 35-40 65-70 35-40
Noise Levels in Selected CitiesMoEF Study
Cities New Method Standard Method
Day/Night Industrial Commercial Residential
CalcuttaDay
Night7867
8275
79 65
Mumbai DayNight
76 65
7566
7062
Chennai DayNight
71 66
7871
66 48
How to tackle noise from the aircrafts: Solution I: Noise reduction at the
source
•Changing the flight path of the aircrafts at theairport.
•Changing the flight schedule and trying to spreadout the noise evenly throughout the day.
•Using less noisy engines in the aircrafts.•Changing the location of the airport.•Shortening the length of the take off and landing
flight segments.
Solution II: Noise reduction at the target
We can use many kinds of sound barriers to this effect.
These barriers can be further subdivided in two categories: passive and active.
The Web-based program pinpoints a home’s location relative to the aircraft noise contours. Anyone with Internet access can type in a street address and quickly learn if the property is within one of the noise contours.
As of December 31, 2004 total disbursements for 106 schools with executed grant agreements as $252.4 million.
Or Community is outreaching
Aircraft Noise Reduction