noise3 by department of environmental quality promotion thailand

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Fig. 1 Map of Measurement Point

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(Leq (24 hrs)) ‡ªìπ®”π«πÀ≈“¬®ÿ¥µ√«®«—¥∑ÿ°ªï µ“¡¡“µ√∞“π ISO ·µà‡ªìπ°“√¬“°∑’®Ë –∑”°“√µ√«®«—¥ Leq (24 hrs) ∑—Ë«æ◊Èπ∑’Ë¢Õß°√ÿß‡∑æ¡À“π§√ ‡π◊ËÕß®“° ¡’æ◊Èπ∑’Ë°«â“ß„À≠à¡“° ®÷ß¡’°“√»÷°…“§«“¡‡ªìπ‰ª‰¥â „π °“√„™â«‘∏’°“√µ√«®«—¥‡ªìπ√–¬–‡«≈“ —ÈπÊ ®“°º≈°“√ »÷ ° …“· ¥ß„Àâ ‡ ÀÁ π «à “ ∂â “ ¬Õ¡√— ∫ §«“¡§≈“¥‡§≈◊Ë Õ π ± 3 ‡¥´‘‡∫≈‡Õ ‡√“ “¡“√∂ª√–¡“≥§à“ Leq (24 hrs) ‰¥â®“°§à“ Leq (10 min) ®“°°“√µ√«®«—¥„π™à«ß‡«≈“ 10:00-18:00 π. ·≈– 22:00-0:00 π.

ABSTRACT At present, noise pollution in Thailand has become a big social problem and getting more serious as other kinds of pollution especially in Bangkok Metropolitan, the center of economic and social development. It has been planning to construct many projects for example express way, outer O-ring road, mass transportation system and the second Bangkok International Airport, in order to support the expansion of the city in the future. To Know the situation of noise problems in Bangkok Metropolitan area, the Pollution Control Department measures Leq (24 hrs) at several sites every year according to ISO. But, it is difficult to get the real Leq (24 hrs) values for the whole of Bangkok because of its large area. The possible short-term method has to be investigated. From the study, the result shows that if + 3 dB(A) error is acceptable, the estimated Leq (24 hrs) value which calculated from a pair of the measurement values of Leq (10 min) during 10:00 to 18:00 oûclock and 22:00 to 0:00 oûclock can effectively represent Leq (24 hrs).

1. Introduction At present, noise pollution in Thailand has become a big social problem and getting more serious as other kinds of pollutionEspecially in Bangkok Metropolis, the center of economic and social development, has been planning to construct many projects for

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examples express way, outer O-ring road, mass transportation system and the second Bangkok International Airport, in order to support the expansion of city in the future. To know the situation of noise problems in Bangkok Metropolitan area, the Pollution Control Department measures Leq (24 hrs) at several sites every year1) according to ISO2). But, it is difficult to get the real Leq (24 hrs) values for the whole of Bangkok because of its large area. The possible shortterm method has to be investigated.3), 4) Up to now, Thailand has no any standard about environmental/community noise. The U.S.EPAûs standard, Leq( 24 hrs) = 70 dB(A), is used1) as a guideline in many cases. In the draft of community noise standard5), show in Table 1, standard levels of long-term and short-term measurement were set according to four kinds of land use. So in order to support the feasibility in using short-term measurement method instead of long-term method, the suitable period of time and time interval in the measurement were tried to find out in this study.

2. Measurement 2.1 Measurement points Measurement points, shown in Fig. 1, were set up 1 point per sq.km. in 9 sq.km. of the inner Bangkok Metropolitan area. This area has been affected by not only road traffic noise but also other kinds of human activities. One of the measurement points was set in a residential area, another in a park and the others, 7 points, were set on roadside.

2.2 Set up for measurement Block diagram of instrumentation for measuring noise continuously 24-hour period is shown in Fig. 2. The Printer was set up to print out the values of Leq(10 min) while the level recorder continuously recording the

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Table 1 Community Noise Standards (Draft) Land use

Standard levels, dB(A) long-term meas. short-term meas.

Agricultural area

Leq(24 hrs) < 55

Leq(5 min) < 60 ;anytime

Residential area

Ld-n < 67

Leq(5 min) < 65 ;daytime

Commercial area

Ld-n < 70

Leq(5 min) < 70 ;daytime < 65 ;nighttime

Industrial area

Leq(24 hrs) < 70

Leq(5 min) < 75 ;anytime Leq(24 hrs) : any 24 hrs. measurement Ld-n : 7:00 - 7:00 next day daytime : 7:00 - 22:00 nighttime : 22:00 - 7.00 next day

sound pressure levels and in each hour the number of vehicles in 10 minutes was counted at the roadside points.

3. Results and discussion The values of Leq(24 hrs), Ldn, Lday (hereafter called Ld) and Lnight(hereafter called Ln) of all measurement points are shown in Table 3. The minimum value of Leq (24 hrs), 55.7 dB(A), was at Areesamphan 6 (residential area) while other three roadside measurement points showed the values over 70 dB(A). The values of Ld and Ln of each roadside measurement point were almost

same levels except a point; which a few events of rather high levels occurred during the measurement, while those values of the measurement points in residential area and park had about 5 dB(A) in difference. Fig. 3 shows variation of difference between Leq(10 min) and Ld, Ln of a point, for daytime during 9:00 or 10:00 oûclock to 18:00 or 19:00 oûclock and for nighttime during 22:00 oûclock to 0:00 or 1:00 oûclock, the differences were approximately within ± 3 dB(A). The average and standard deviation of the difference between Leq(10 min) and Ld,

Fig. 2 Instrumentration for Noise Measurement §-88

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Table 2 Result of Measurements Measurement Points 1. 2. 3. 4. 5. 6. 7. 8. 9.

Areesamphan 6 Excise Dep. Dusit Dist. Off. Dusit zoo Welfare Fac. Phayatai 2 Hosp. Millitary Dep. Phayatai School Horse Race Course

Location

Leq (24hrs)

Ldn

Lday

Lnight

residential area roadside roadside Park 25 m. from road roadside roadside roadside roadside

55.7 74.0 69.5 58.0 68.5 77.1 71.2 69.7 68.0

59.9 80.1 52.5 62.6 74.7 83.8 76.8 73.1 74.4

57.0 74.4 69.9 59.2 68.7 77.0 71.8 71.1 68.0

51.5 73.3 68.8 54.5 68.2 77.1 70.1 65.2 68.1

(measurement date : 28-30 Nov.1995) daytime : 7:00 - 22:00 nighttime : 22:00 - 7:00 next day

Table 3 Summary of the Average and Standard Deviation of the difference between Leq(10 min) and Lday, Lnight Daytime Measurement Points

1. 2. 3. 4. 5. 6. 7. 8. 9.

Areesamphan 6 Excise Dep. Dusit Dist. Off. Dusit zoo Welfare Fac. Phayatai 2 Hosp. Millitary Dep. Phayatai School Horse Race Course

Avg. of Diff. 7:00- 10:0022:00 18:00 -1.16 -1.32 -0.21 0.08 -0.20 -0.28 -0.50 0.01 -0.41 -0.90 -0.25 -0.46 -1.10 -1.67 -3.41 -3.38 -0.23 -0.44

S.D. 7:00- 10:0022:00 18:00 3.01 2.85 1.37 1.07 1.23 0.93 2.49 0.99 1.86 1.62 1.42 1.45 2.28 1.23 1.88 1.67 1.87 1.66

Nighttime Avg. of Diff. 22:00- 22:007:00 0:00 -3.82 -1.36 -1.22 -1.13 -0.71 1.70 -0.91 -1.07 -0.50 0.59 -0.18 -0.56 -0.22 -0.20 -0.18 0.63 -0.19 0.41

S.D. 22:00- 22:007:00 0:00 5.79 4.16 3.03 1.13 2.38 2.32 2.54 0.75 2.20 1.38 1.23 0.91 1.35 1.26 1.26 0.87 1.35 0.95

Fig. 3 Difference between Leq(10 min) and Lday, Lnight : 1. Areesamphan 6

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Ln during 10:00 to 18:00 oûclock and 22:00 to 0:00 oûclock were calculated and compared to the whole daytime and nighttime values as shown in Table 3. The values of the average of the difference of all measurement points in daytime changed not so much. On the other hand, most of those values at nighttime shifted to a little higher because Leq(10 min) tend to decline from about 1:00 oûclock and rised up about 5:00 oûclock. And most of the values of the standard deviation became smaller. Each pair of Leq(10 min) during 10:00 oûclock to 18:00 oûclock and 22:00 to 0:00 oûclock was calculated to be an estimated Leq (24 hrs) value, Leq(24 hrs)est, by using the following formula; Leq(24 hrs)est = 10 log 1/24(15*10Leq(10 min)day/10 +9*10Leq(10 min)night/10) It was found that more than 80% of Leq(24 hrs)est values were within ± 3 dB(A) different from the true Leq(24 hrs). Fig. 4 shows histogram of a point.

4. Conclusion If within ± 3 dB(A) error is acceptable, the estimated Leq(24 hrs) value which calculated from a pair of the measurement acceptable values of Leq(10 min) during 10:00 oûclock to 18:00 oûclock and 22:00 to 0:00 oûclock will be effectively represent Leq (24 hrs).

5. Acknowledgment The authors would like to thank the hosts of measurement points for their assistance in setting up the measuring instruments. This research has been supported by the Technical Cooperation Project between the Government of Japan and the Kingdom of Thailand, and was carried out under JICA (Japan International Cooperation Agency) expertûs guidance.

6. References 1. Pollution Control Department, Ministry of Science Technology and Environment, Thailand, (1994) Report of Pollution Situation in Thailand, 31-33

Fig. 4 Cumulative frequency of difference between Leq(24 hrs)est and Leq(24 hrs)obs

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2. ISO 1996/1, (1982) Description and Measurement of Environmental Noise 3. C.M. Harris; (1979) Handbook of Noise Control, Mcgraw Hill, 35-23-26 4. I. Aoi, G.Hathairatana (ERTC), 1992 Temporal Sampling Techniques for the

measurement of Environmental noise (Total Measurement time), JICA Final Report 5. National Environment Board, (1993) Thailand, Community Noise Standard (Draft)

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