Environmental impact assessment of subway light rail project?

Urban rail transit environmental impact assessment Noise vibration Urban rail transit not only plays a backbone role in urban passenger transport, but also has obvious advantages in guiding urban planning and construction, promoting land development and utilization, and promoting real estate economic development. However, the negative impact of rail transit on the environment, especially the noise and vibration generated during the construction and operation of rail transit, has attracted more and more attention. For ground or overhead lines, noise has the most prominent impact on the environment; For underground lines, its vibration influence is the primary environmental problem. Therefore, in the environmental impact assessment of urban rail transit, acoustic environmental impact assessment and vibration environmental impact assessment are usually listed as special topics as the evaluation focus, which is an important part of the environmental impact report. In the process of evaluating the impact of acoustic environment and vibration environment, special attention should be paid to the following issues when conducting special evaluation of acoustic environment and vibration environment.

1. Adequacy of environmental protection objectives. The environmental protection targets within the evaluation scope should be fully investigated, and the content and investigation should be comprehensive and sufficient from the types, functions, time, regions, distribution and characteristics of sensitive protection targets.

1) Teaching units, medical units, important scientific research units, kindergartens, sanatoriums, residential buildings, world cultural heritage, cultural relics protection units at all levels and protective buildings are all regarded as environmental protection objects.

2) The environmental protection target with the same function contains multiple environmental sensitive points. Environmental sensitive points refer to school classrooms, student dormitories, hospital wards, nursing homes and homes for the aged, and residential buildings within the evaluation range on both sides of the track.

3) Time and environmental protection targets include not only existing buildings, but also future environmental protection targets exposed after demolition. Those that need to be re-planned and have not yet been realized should be listed as environmental protection targets.

4) The regional environmental protection objectives include not only the existing buildings in the built-up area, but also the buildings under construction, preparation and construction that have been approved by the planning department, and should be included in the environmental impact assessment scope in combination with urban planning. In general, when rail transit is put into operation, environmental complaints often occur before rail transit is put into operation, but they are not included in environmental impact assessment.

5) The evaluation range of distributed acoustic environmental impact and vibration environmental impact is determined according to the evaluation grade. The acoustic environmental protection objectives within the evaluation scope are divided into two categories: the impact of train noise and the impact of wind pavilion and cooling tower noise. The protection targets affected by train noise are generally distributed on both sides of overhead lines and ground lines, especially on interval lines, or on both sides of access lines and around depots or parking lots; However, the protection targets affected by the noise of wind pavilions and cooling towers are generally distributed around underground line stations. The vibration environmental protection targets within the evaluation scope are basically distributed on underground lines or overhead lines, especially on both sides of interval lines. In other words, the environmental protection targets on both sides of overhead lines and ground lines are affected by the noise and vibration of trains, mainly the noise of trains; The environmental protection targets on both sides of the subway line are affected by train vibration, and the environmental protection targets around the subway station are affected by the noise of wind pavilions and cooling towers. Therefore, for overhead lines and ground lines, the environmental protection targets on both sides of the lines can be used as acoustic environmental protection targets and vibration environmental protection targets at the same time in the evaluation; For underground lines, acoustic environmental protection targets and vibration environmental protection targets are different protection targets respectively.

6) The environmental protection target whose characteristics are included in the evaluation category should give the following information according to environmental factors: the name of the protection target, line shape, section between stations, mileage position, relative position relationship with sound (vibration) source plane and space (direction, distance, buried depth, height difference), building type, function, floor, quantity, construction year, number of people affected, environmental function area, implementation standard and pollution source type.

2. Accuracy of source intensity analogy

2. 1 strong noise vibration source The prediction of rail transit noise vibration impact is an important part of acoustic environmental impact assessment and vibration environmental impact assessment, and the determination of rail transit noise vibration source strength is the key to the prediction of rail transit noise vibration impact. Among them, the noise sources that need to be considered are: train operation noise (vehicle equipment noise, wheel-rail noise, bridge structure radiation noise), wind pavilion and cooling tower noise, vehicle section operation noise and other noise sources that may have an impact on the environment, as well as train operation vibration, tunnel structure and bridge structure radiation vibration.

2.2 Determination of the intensity of noise and vibration sources There are generally two methods to determine the intensity of noise and vibration sources, namely, analog measurement method and data analogy method. Analogy measurement method is to select vehicles (equipment) of the same type and group as the new project, and measure the running noise of the train (equipment) analogously under similar operating conditions, line forms, track structures and environmental conditions, and make necessary acoustic corrections according to the differences of analogy conditions; Data analogy method, also known as data investigation method, refers to the measurement data of existing noise sources or vibration sources under similar conditions such as vehicle (equipment) type, operating conditions, line form, track structure and environmental conditions. Which method to choose to determine the source intensity depends on the requirements of evaluation grade. For the evaluation topics of the first-level evaluation level, the analogy measurement method must be adopted; The data analogy method can be used for the evaluation subject with the evaluation grade of Grade II or below. In the simulation measurement, the key requirement is the consistency of boundary conditions such as measurement object, measurement parameters, measurement method, measurement quantity and measurement environment, that is, the types, operating conditions, line forms, track structure and environmental conditions of existing vehicles (equipment) and new project vehicles (equipment) are as similar as possible, and the noise of existing trains (equipment) is simulated and measured according to the measurement methods specified in relevant measurement standards. To quote the existing measurement data, it is also necessary to quote the source data by analogy, and explain the measurement conditions under the condition that the boundary conditions such as the measurement object, measurement parameters, measurement methods, measurement quantity and measurement environment are similar. Analogy citation should explain the data source, which should be published publicly and identified by experts.

3. Applicability of prediction parameters

3. 1 noise and vibration prediction parameters In order to reduce the error of the prediction results, it is necessary to make necessary acoustic corrections to the simulated measurement data of the existing source intensity according to the difference between the boundary conditions of the existing source intensity and the simulated source intensity, so as to make the simulated source intensity more accurate. In addition, in order to predict the noise and vibration influence of the sound (vibration) receiving point, the propagation path and characteristics of the sound (vibration) receiving point should be considered. The influence of noise and vibration on sound (vibration) receiving point is related to the characteristics of sound (vibration) source, propagation path and sound (vibration) receiving point. Noise and vibration prediction parameters include the characteristic parameters of sound (vibration) source, propagation path and sound (vibration) receiving point. Different line forms have different environmental impacts, which are related to various engineering conditions such as lines, tracks, bridges, tunnels, wheels and rails, vehicles, equipment, operation organization, operation scheme and the relative position relationship between sensitive points and sound (vibration) sources. Above-ground lines include overhead lines, ground lines, access lines, vehicle depots or parking lots. The noise impact on environmental protection targets is mainly produced during the running of trains, and is influenced by the relative position relationship between vehicles, operations, wheels and rails, bridges, traffic organizations, sensitive points and sound sources. The noise impact of underground lines on ground buildings is mainly caused by wind pavilions, cooling towers and other equipment and facilities, and is affected by equipment and its operation and installation mode, installation location, equipment quantity, operation time, distance and height from sensitive points to noise sources and other factors.

3.2 Applicability selection of prediction parameters Because different line forms cause different noise sources, in the acoustic environmental impact assessment, the applicability of prediction parameters related to train noise and equipment noise should be judged according to different prediction contents and prediction purposes, combined with the actual situation of vehicles, equipment, operations, tracks, tunnels and bridges. At the same time, for the main train noise and the train noise inside and outside the interval line, appropriate prediction parameters should be selected according to different track conditions (ballast, sleepers, fasteners), train speed, number of running trains, running time, etc. , so as to predict the impact of noise, and explain the impact degree, scope and exceeding the standard of various rail transit noises respectively.

In the process of using mathematical model to predict environmental impact, we should try to choose a universal, mature, simple and accurate method. When necessary, the calculation results of the prediction model should be verified, including the actual measurement of the mathematical model to be established or the verification of the prediction method verified by the actual measurement.

4. Consistency of monitoring points, prediction points and protection targets

4. 1 Layout of monitoring points and prediction points

(1) The monitoring range and prediction range of noise and vibration generally correspond to the evaluation range, and the evaluation grade determines the evaluation range. Therefore, the coverage of environmental monitoring and environmental prediction is determined according to the evaluation grade. According to the requirements of the first-level evaluation grade, the layout of current monitoring points should generally cover the whole evaluation range and should be measured; Environmental prediction points should cover all sensitive targets within the evaluation scope.

(2) The layout of current monitoring points should pay attention to the points where the existing noise sources and vibration sources have influence on sensitive protection targets, and distinguish the influence degree of rail transit noise and vibration on the existing noise and vibration, so as to determine the contribution of rail transit noise and vibration to the environmental impact.

(3) The layout of current monitoring points should also consider sensitive protection targets that need special attention within the evaluation scope. For example, the sensitive protection target located above the tunnel or within 0/0 meter from the track center line/kloc-0, whose building type is Class II (brick-and-wood bungalow or simple building), should be monitored at selected points in the building.

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