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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