Pengukuran Noise Ahmad Suudi, S.T., M.T.. 2 Noise Measurement Significant variability in noises from...
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Transcript of Pengukuran Noise Ahmad Suudi, S.T., M.T.. 2 Noise Measurement Significant variability in noises from...
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- Pengukuran Noise Ahmad Suudi, S.T., M.T.
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- 2 Noise Measurement Significant variability in noises from transportation sources L p : noise level at a particular receptor that is exceeded p percent of the time i.e. Noise that exceeds 100 dB 90% of the time A-weighted noise level (equivalent irritation level has to do with mix of frequencies DNL (day/night level weights nighttime noises)
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- 3 http://www.nonoise.org/library/highway/policy.htm#II What are L 10 and L eq ? The equivalent sound level is the steady- state, A-weighted sound level which contains the same amount of acoustic energy as the actual time-varying, A- weighted sound level over a specified period of time. If the time period is 1 hour, the descriptor is the hourly equivalent sound level, Leq(h), which is widely used by SHAs as a descriptor of traffic noise. An additional descriptor, which is sometimes used, is the L10. This is simply the A-weighted sound level that is exceeded 10 percent of the time.
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- 4 http://www.nonoise.org/library/highway/traffic/traffic.htm What are L 10 and L eq ? L 10 is usually about 3dB greater than L eq
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- 5 Mathematical Model Simple model L 50 = 68 + 8.5 log V 20 log D (dB) Where: V = traffic volume (veh/hour) D = distance from traffic to observer in feet Also use nomographs, relate noise to speed, volume, distance, etc.
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- 6 State of the Art is FHWAs Traffic Noise Model (TNM) Modeling of five standard vehicle types, including automobiles, medium trucks, heavy trucks, buses, and motorcycles, as well as user-defined vehicles. Modeling of both constant-flow and interrupted-flow traffic using a 1994/1995 field- measured data base. Modeling of the effects of different pavement types, as well as the effects of graded roadways. Sound level computations based on a one-third octave-band data base and algorithms. Graphically-interactive noise barrier design and optimization. Attenuation over/through rows of buildings and dense vegetation. Multiple diffraction analysis. Parallel barrier analysis. Contour analysis, including sound level contours, barrier insertion loss contours, and sound- level difference contours.
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- 7 2280 120 60 Problem: Find dBA L 10 500 ft from road 2 lane road 2400 vehicles per hour 5 percent trucks 60 mph #cars =.95x2400=2280 Example Problem
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- 8 Problem: Find dBA L 10 at 500 ft From a 2 lane road carrying: 2400 vehicles per hour 5 percent trucks, at 60 mph cars =.95x2400=2280 L 50 dBA for cars at 100 = 68 dBA
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- 9 68 2280 120 60
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- 10 Problem: Find dBA L 10 at 500 ft From a 2 lane road carrying: 2400 vehicles per hour 5 percent trucks, at 60 mph trucks =.05x2400=120 L 50 dBA for trucks at 100 = 62 dBA 20 30 40 50 60 70
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- 11 6862 2280 120 60
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- 12 Problem: Find dBA L 10 at 500 ft From a 2 lane road carrying: 2400 vehicles per hour 5 percent trucks, at 60 mph O-ELD = 500
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- 13 Problem: Find dBA L 10 at 500 ft From a road carrying: 2400 vehicles per hour 5 percent trucks, at 60 mph Adjustment from 100ft ref = -10 dB
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- 14 6862 -10 2280 120 60
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- 15 Problem: Find dBA L 10 at 500 ft From a road carrying: 2400 vehicles per hour 5 percent trucks, at 60 mph (vol/speed)*ELD = 19,000 for cars, 1,000 for trucks L 10 - L 50 = 2 dBA cars, 6.5 dBA trucks
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- 16 6862 -10 2 6.5 6058.5 6058.5 2280 120 60
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- 17 Adding 2 sources Heavy trucks 58.5 dB Passenger vehicles 60 dB
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- 18 Difference = 60 58.5 = 1.5 Add 2.3 dB to higher 60 + 2.3 = 62.3 dB due to both sources
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- 19 6862 -10 2 6.5 6058.5 6058.5 62.3 2280 120 60
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- 23 Other Adjustments Grade (trucks) +/- 3-4%= +2 +/- 5-6% = +3 +/- >7 = +5 Surface very smooth = -5 (auto only) very rough = +5 (auto, or truck>60mph) Interrupted flow (L 10 ) auto = +2 Truck= +4 Foliage -5 for each 100 >15 -10 max Rows of houses -5 for each -10 max
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- 24 Noise Barriers
- Slide 25 C Source:http://www.urbislighting.com/uap1.html">
- 25 Noise Barriers (how they work) Noise is "diffracted" over the barrier, this increases the distance it travel to the listener, thus decreasing the noise A + B > C Source:http://www.urbislighting.com/uap1.html
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- 26 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers
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- 27 Noise Barriers (how they work) Noise is also reflected and/or absorbed Source:http://www.urbislighting.com/uap1.html
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- 28 http://www.nonoise.org/library/highway/traffic/traffic.htm Possible barriers
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- 29 http://www.nonoise.org/library/highway/traffic/traffic.htm
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- 30 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers
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- 31 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers
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- 32 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers
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- 33 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers
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- 34 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers
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- 35 Source: FHWA, Keeping the Noise Down, Highway Traffic Noise Barriers