Analysis on the environmental impact assessment st

2022-08-21
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Analysis on the environmental impact assessment standard of urban rail transit noise in the United States

Abstract: through a comprehensive analysis of the essence and formulation basis of the noise impact assessment standard of urban rail transit projects in the United States, and based on the characteristics of the standard, this paper puts forward suggestions for the formulation and improvement of the noise impact assessment and control standard of urban rail transit projects in China

key words: rail transit; Noise; Evaluation criteria; U.S.

1 Introduction

the federal public transport administration of the U.S. Department of transportation issued the guidelines for environmental impact assessment of noise and vibration of federal public transport projects in 1995, which proposed a set of environmental impact assessment standards for noise of urban rail transit projects, This standard is applicable to all urban rail transit projects (subway, light rail, automatic guide rail, etc.) and their fixed facilities (depot and parking can stretch, shrink, zigzag, low cycle and high cycle fatigue, crack expansion, fracture mechanics test field, station, substation, etc. under sine wave, 3-angle wave, square wave, trapezoidal wave, oblique wave, user-defined waveform). At present, there is no noise environmental impact assessment standard for urban rail transit projects in China. It is not scientific and operable to evaluate the noise impact of urban rail transit projects by comparing with the standard of urban regional acoustic environment functional area. However, this set of standards in the United States has some enlightenment for China to study and formulate the noise environmental impact assessment standard of urban rail transit projects

2 contents of the noise impact assessment standard for urban rail transit projects in the United States

the environmental impact assessment standard for urban rail transit projects in the United States is based on the added value of the environmental noise level in the area where the rail transit project is located before and after the implementation of the project, and the standard value is determined according to the specific land use category of the project affected area. The evaluation standard includes the absolute standard, that is, the standard value for distinguishing the noise impact of the rail transit project itself according to the land use category of the project area; It also includes the relativity standard, that is, the added value of the environmental noise level before and after the implementation of the rail transit project, and the standard value for judging the noise impact according to the land use category of the project area. The noise evaluation quantities used in this standard are Leq (H) and LDN. Leq (H) refers to the maximum 1H equivalent sound level of rail transit noise, while LDN refers to the 24h equivalent sound level throughout the day (the correction value of 10dB (a) at night). See Table 1 for the corresponding relationship between the land use category and the noise evaluation quantity of the area along the project on which the standard is based

there are two curves in Figure 1, and each curve is composed of three parts. The rail transit noise in the initial part increases linearly with the background noise; The rail transit noise in the middle part increases with the background noise by cubic polynomial; The last part has nothing to do with the background noise and is the maximum limit of the noise of rail transit itself. The two curves in Figure 1 constitute three noise impact assessment discrimination areas. In the area below the low-level curve, it shows that the rail transit noise has no impact on the surrounding land use function, because, on average, the proportion of noise annoyed people increased due to the addition of rail transit noise has not yet exceeded the proportion set by the low-level curve; The area between the low-level curve and the high-level curve shows that the rail transit noise has an impact on the surrounding land use function, that is, the proportion of noise annoyed people increased due to the addition of rail transit noise has exceeded the proportion set by the low-level curve, but has not yet exceeded the proportion set by the high-level curve. Generally speaking, the increase of environmental noise caused by rail transit noise has been more public awareness, and a certain proportion of people are annoyed, But it has not made the public feel strongly disgusted; In the area above the high-level curve, it shows that the rail transit noise has a serious impact on the surrounding land use function, that is, the proportion of noise annoyed people increased due to the addition of rail transit noise has exceeded the proportion set by the high-level curve, which has made the public feel strongly disgusted

the core variable of the noise impact assessment standard of rail transit projects in the United States is the added value of environmental noise before and after the implementation of rail transit projects. Under the control condition of meeting the constant increasing proportion of noise annoyed people, the evaluation criteria with the added value of environmental noise as the evaluation variable are formulated

3 basis for the formulation of noise impact assessment standards for urban rail transit projects in the United States

3.1 dose response relationship of the public to traffic noise

the U.S. Environmental Protection Agency carried out a large number of investigations and studies on the response of the community public to noise in the 1970s, and the results were widely recognized by the federal noise Coordination Commission, the U.S. Department of housing and urban development, the American Standards Association and the International Acoustic community. According to the investigation and research results of the U.S. Environmental Protection Agency, traffic noise is the most disgusting to the public. The dose-response relationship of the public to traffic noise is summarized in Figure 2 by the odore hultz, that is, Schultz curve. In recent years, additional investigations and studies have been made on railway noise, rail traffic noise and street traffic noise, and the shape of Schultz curve has been further confirmed

3.2 determination basis of low and high level curves

3.2.1 according to the view of the U.S. Environmental Protection Agency, the community environmental noise level is lower than or equal to 55dB (a), which is necessary for public health and welfare and is fully guaranteed. And the noise level expressed in LDN or Leq can cause the minimum sound level change of 5dB (a) perceived by the public in the conceptual area of social metal materials with yield, upper yield and lower yield

3.2.2 according to the environmental noise standard of the U.S. Department of housing and urban development, LDN equal to 65dB (a) is usually an unacceptable residential environmental noise limit. At the same time, the Federal Aviation Administration also believes that areas with LDN greater than 65dB (a) cannot be used as residential areas

3.2. 3 according to hultz's research results, when LDN is equal to 50dB (a), almost no one complains about the impact of environmental noise. From LDN is equal to 50dB (a) to 55dB (a), an average of 2% of the population complains about the impact of environmental noise; Because the minimum sound level change perceived by the public is 5dB (a), the lowest detectable impact is from the background noise of 50dB (a) to the environmental noise of 55dB (a) after adding the rail transit noise. In other words, from LDN equal to 50dB (a) to 55dB (a) is the lowest limit of noise impact, and the average 2% of the annoyed people is the smallest measurable public response; In this way, the characteristic points of the low-level curve are set at the background noise level of 50dB (a), while the rail transit noise level is 53db (a), and the superimposed environmental noise is 55dB (a). Other parts of the low-level curve are determined by the schults curve according to the principle that the increase in the percentage of significantly troubled people caused by the increase of environmental noise must be 2%. In order to maintain the increase of the percentage of significantly annoyed people must be 2%, then with the increase of background noise, the increase of superimposed environmental noise will be less and less. For example, when the background noise is 50dB (a), in order to maintain the increase of the percentage of significantly annoyed people must be 2%, the increase of superimposed environmental noise must be 5dB (a), and when the background noise is 70dB (a), in order to maintain the increase of the percentage of significantly annoyed people must be 2%, The increase of ambient noise after superposition is only 1dB (a)

3.2. 4 similar to the low-level curve, the minimum sound level change from the noise level acceptable to the public to the noise level unacceptable to the public is represented by the increase of the ambient noise from 60dB (a) of the background noise to 65dB (a) after the rail transit noise is added. According to the research results of ultz, from LDN equal to 60dB (a) to 65dba), an average increase of 65% of people complain about the impact of environmental noise; In this way, the characteristic points of the high-level curve are set at the background noise level of 0dB (a), while the rail transit noise level is 63dB (a), and the superimposed environmental noise is 65dB (a). Other parts of the high-level curve must be determined by the schults curve according to the principle that the increase in the percentage of significantly troubled people caused by the increase of environmental noise must be 65%

3.2. 5 due to the lack of public dose-response relationship to noise lower than 45dB (a) in the schults curve, the standard setter followed the Federal Highway Administration's highway noise impact evaluation principle, that is, the project's own noise level increased by 10dB (a) compared with the background noise level has an impact, and increased by 15dB (a) has a serious impact. It was conservatively formulated that the sample can be taken out under the low background noise for experiment, Impact evaluation curve of rail transit noise

3.2. 6 for the maximum limit value of rail transit noise, the standard stipulates that the rail transit noise is equal to or more than 65dB (a) as having an impact (Class 1 and class 2 land use areas), and equal to or more than 75db (a) as having a serious impact (Class 1 and class 2 land use areas)

3. 2.7 it should be noted that because the sensitivity of class 1 and class 2 land use areas to noise is different from that of class 3 land use areas, the standard stipulates that for class 3 land use areas, the corresponding standard value is 5dB (a) wider than that of class 1 and class 2 land use areas, which has been clearly marked in Figure 1

4 characteristics of environmental impact assessment standards for urban rail transit projects in the United States

4 Strong scientificity: the original data on which the standard is formulated has been recognized by the environmental protection and acoustic circles in the United States and internationally

4. 2. Strong operability: first, the noise protection area (land use area) is clear; second, under the acceptable noise level of the public, the background noise that the public has been accustomed to is fully considered, and the proportion of significantly troubled people that increase with the increase of environmental noise is controlled within an appropriate range

4.3 give full consideration to the sensitivity of land use areas to noise, and reasonably allocate noise protection. For example, the sensitivity of class 3 land use areas to noise is considered to be lower than that of class 1 and class 2 land use areas, and their sensitive activities are mainly indoors. The noise can be attenuated through building structure measures, which is more economical than taking measures from rail transit engineering

5 Enlightenment on the formulation of noise impact assessment standards for urban rail transit projects in China

urban rail transit plays an important role in urban public transport. At present, Beijing, Shanghai, Guangzhou and Shenzhen have rail transit operation lines, and Nanjing, Wuhan, Dalian, Harbin, Suzhou and other cities are actively preparing for construction. It can be expected that rail transit will be widely used in large and medium-sized cities in China. The main impact of rail transit projects on the environment is noise. At present, there is no standard on the evaluation of rail transit noise impact in China. In practice, the noise impact assessment is carried out according to the current environmental noise standard for urban areas [2]. Compared with the American rail transit noise impact assessment standard, China can make the following exploration on the rail transit noise impact assessment standard:

(1) establish a discrimination standard for urban rail transit noise impact assessment, which is not cross used with the current urban regional environmental noise standard. According to the noise impact assessment standard of urban rail transit projects in the United States, combined with the actual situation of our country, according to the specific use function of noise sensitive buildings, and considering the subjective response ability to the increase of environmental noise that they have been used to, it will be very necessary to formulate a discrimination standard for the noise impact assessment of urban rail transit in our country

(2) with the continuous development of urban functions in China, the flow of people and logistics is more and more frequent, and the noise of urban transportation facilities and urban life are more and more. It is more and more difficult to evaluate and control the noise impact according to the functional area. Therefore, it is more meaningful to formulate noise impact evaluation and control standards for the specific use functions of noise sensitive buildings. Therefore, it will be more effective to modify the current "environmental noise standard for urban areas" according to the specific use functions of noise sensitive buildings. If so, cities can be considered

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