Determination of limits for acoustical pollution from main roads at the stage of urban area zoning

The intensive automobilization of cities involves some problems relating to traffic arrangement, and as a result, requires to extend th e transportation corridors of main trunk road networks, increase traffic capacity, and develop models of transportation flows in the conditions of ex isting urban development. In such conditions, environmental pressures on urban areas increase. The impact of technogenic factors on the areas also increases, and as a result, the concentration of environmental pressures enhances. The desire to increase the traffic capacity and city building den sity can induce ecological instability of some urban areas. At the present time, there are normative documents that regulate the conditions for development and planning of urban areas. The functionality of urban areas and environmental pressures on the areas and their limits must be clearly determined at the stages of developing the general plans and detailed plans of the urban area development. In the conditions of decentralization and formation of territorial communities, which are entitled to independently deal with their financial problems and form social living environment, it is required to use comprehensive professional methods for designing strategic programs for the development of cities and settlements. At the present time, city planning specialists are capable of taking into account various factors relevant to the development and planning of urban areas with consideration for future environmental pressures and their limits. Due to this, it will be possible to save financial costs when carrying out actions required for decreasing the technogenic impact on the ecology and living environment, and planning the perspectives of regional development. For this reason, the analysis of environmental pressures from the city main roads network is relevant for any city. This paper contains the calculated data on the results of analysis of the city main roads characte ized by different planning concepts. These data are required for determining the corresponding planning actions.


INTRODUCTION
Acoustic pollution of urban areas is one of the negative results of the intensive automobilization of the country cities. The determination of levels of noise generated by various noise sources, as well as the estimation of noise propagation within the urban area is characterized by specific features and depends on the noise source characteristics and on the city planning stage at which the noise propagation is estimated. With consideration for this, at the detailed planning stage, an effective method was developed for drawing up noise charts for stationary and mobile noise sources. This method allows constant noise level lines (isodecibels) clearly to be drawn, and accordingly, the noise level in every specific urban area to be determined. For this purpose, it is required to have cartographic documents for the city planning area, at a scale of 1:500 through 1:2000, data on the road cross sections and road characteristics, and data on the parameters of transportation flows. But at the stages of technical and economic assessment, development of diagrams and projects according to the general city planning scheme, and preparation of cartographic documents at a scale of 1:10000 through 1:25000, or even 1:50000, there are no need and possibility to draw up the detailed charts characterizing the noise pollution in the areas studied. At these project stages, the estimation of acoustic pollution consists only in determining the predicted noise levels from various noise sources and drawing up noise diagrams. In this case, it is possible to compare different main roads depending on noise levels and distinguish the noisiest streets, but it is impossible to estimate the degree of noise propagation within the urban area.

STATEMENT OF THE PROBLEM
The purpose of this study is to determine the limits of acoustic impact of the city main roads when specifying the functionality of the urban areas at the stage of zoning the urban area and designing the detailed urban area plan. The development of a model for environmental pressures, with consideration for their impact, and the prediction of extension of the environmental pressures on the certain planning area is one of the purposes of activity in city planning.

ANALYSIS OF THE LATEST RESEARCH AND PUBLICATIONS
The results of analysis of scientific papers and effective normative documents relating to city planning demonstrate the actuality of this study issue, as the intensive automobilization of cities more and more promote the study of factors which have an effect on transportation flows simulation and on environmental pressures on the urban area. The city transport and the ecological state of the city environment are subjects of studies by such well-known specialists as , Diomin M.M., Reitsyn Ye.O., and others. The stable integrated approach in performing scientific studies will promote the introduction of new practical methods in the planning and arrangement of urban areas at the corresponding planning stage.

LIMITS FOR ACOUSTICAL POLLUTION FROM MAIN ROADS AT THE STAGE OF URBAN AREA ZONING
For the predictive estimation of noise pollution of urban areas from line noise pollution sources, a method was developed for analyzing propagation of noise from the city main roads inward the urban areas located near the streets [23,24]. Specifically, at the stage of the urban area zoning, when different functional zones in the urban area are to be identified, there is a possibility to take into account the normative allowable noise levels and the characteristic features of the corresponding urban areas [25].
In this case, the following unbuilt and builtup urban areas with various allowable noise levels are defined: • areas with long-completed buildings, which are subjected to reconstruction, and areas of industrial enterprises and estates: 60 dB(A). When performing acoustical analysis in such a case, it is recommended to determine noise pollution paths, that is, the areas located near line noise pollution sources, such as automobile roads and railways, with noise levels arranged between the isodecibels corresponding to the normative noise levels. It is accomplished by plotting limiting acoustic discom-fort characteristics, which separate noisepolluted areas from areas with acoustic comfort conditions, that is, from the areas where noise levels are less then the noise levels specified in the sanitary standards [23,24].
It is appropriate to determine the width of noise propagation paths according to the method described in [26], using a noise recorder developed in the Dnipropetrovsk Civil Engineering Institute [27]. crease of noise levels in unbuilt areas and in spacings of buildings located at the specified distance from the border line [27] For the possibility to use a noise recorder, we determined, on the basis of the experience achieved in designing and analyzing various building projects, the following average spacing of buildings for various building types: • for industrial buildings, such as production plant buildings, industrial facilities, warehouses, and garages: 10 m; • for low-rise and mixed buildings: 15 m; • for high-rise buildings: 20 m.
When performing overall calculations, it is assumed that roadside planted land in areas with individual and single-floor buildings decreases noise levels by 5 dB(A).
Limiting acoustic discomfort characteristics should be plotted as follows: • within unbuilt areas, noise propagation should be determined according to the characteristic describing the propagation of noise from a line noise pollution source [26], or according to the first part of the noise recorder data [27] (Fig.1 a) termined in the same manner as for unbuilt areas but with consideration for the noise attenuation by 5 dB (A) due to the presence of the planted land; • in areas with buildings of different types, the width of noise propagation paths should be determined according to the spacing's of buildings (Fig.1 b, c, d, e) with consideration for the characteristic features of the buildings and the characteristics of traffic arteries. By using a noise recorder, for the specified spacing's of buildings and widths of traffic arteries within the controlled building-up areas, it is required to determine the distance at which the calculated level of noise caused by the presence of the traffic artery decreases to the sanitary standard level.
When determining the width of the noise pollution path from a railway, it is assumed that the basic normative requirements are fulfilled for providing sanitary protection area 100 m in width and 50-percent planting of the area. In this case, it should be considered that the decrease of noise levels by plants in the sanitary protection area is 6 dB (A) on an average. If the traffic artery is located within the railway right of way, the noise levels caused by both the noise pollution sources should be added with consideration for the noise energy generated by each source.
As an example, the use of the proposed method is illustrated by the data in Table 1, obtained in calculating the traffic noise levels from the main roads in Solomianskyi District in Kyiv. The noise propagation paths caused by automobile and railway transportation vehicles and determined according to the abovementioned method can be shown on the city district development map at the map scale. The data on the noise propagation paths can be used as basic data for differentiating the urban areas, developing more substantiated noise protection facilities, and taking decisions in relation to the planning and development of the urban areas.

CONCLUSIONS
The calculated data presented in this paper can be used as basic data in determining limit environmental pressures on the urban areas located near main roads, specifying the functionality of the urban areas, and taking the corresponding decisions for providing the quality of the city environment, selecting methods for the technical protection of the urban areas, studying the urban areas in conditions of compact planning, determining the type of building-up along the city main roads, and simulating the ecological state of the city environment.