K. Karnaukh, U.I. Zakharov, L.V. Druzhinina

Pridneprovsk state academy of civil engineering and architecture, Dnipropetrovsk, Ukraine

MODERN TECHNIQUES IN NOISE PREDICTION

It is a well known fact that noise is a serious public health problem. Noise is recognized as a dangerous health hazard as well as a nuisance.  With urbanization and corresponding increase in number of vehicles in metropolitan cities, the pollution is increasing at an alarming rate. In the world the majority of citizens live in noisy surroundings. Urban areas are often located in close proximity to major transport axes, such as railway stations, main roads, airports and flight paths.

The most vulnerable members of society are often the most affected: the children, the old people and those who always suffer from physical or mental health problems. There is a general information about the health problems caused by noise impacts: environmental noise above 40-50dBA Leq is likely to lead to significant annoyance; noise levels between 65-70 dBA Leq may be risk factors for ischemic heart disease; outdoor noise levels of 40-60 dBA Leq may disturb sleep; traffic noise of 70dB (A) may cause hearing impairment.

Therefore prediction and estimation of noise is extremely important in the planning of new roads and railway tracks, industrial facilities and airports near cities and other residential areas. To create a healthy and noise pollution free environment a noise prediction model is needed so that the noise level along a busy highway can be predicted and investigated in advance during the planning and design process (Brown and Macdonald 2003). The level of highway traffic noise depends mainly on the following factors: volume of the traffic, speed of the traffic, number of the heavy vehicles in the flow of traffic.

Most of the countries, keeping in view the alarming increase in environmental noise pollution, have given the permissible noise standards, predicting and estimating technics. The EU Directive 2002/49/EC mandates that noise maps are produced for all roads, railways and civil airports, to inform strategic planning for noise control. However, measurement based approaches using conventional sound level meters are not practical, mainly for economic reasons. Therefore, the Directive currently requires maps to be produced using noise prediction models, with all their inherent assumptions and limitations.

Many different methods are used to predict noise levels in the environment caused by roads, railways, industrial plants and other sources. They comprise the calculation of sound emission values from the identifiable technical parameters and the calculation of sound propagation in all practically relevant environmental conditions. These methods can be constructed with extremely different degrees of complexity and it is very important to find a good balance between scientific correctness and economic needs.

Many calculation methods are used in different countries to estimate the noise caused by road traffic sources. The first step is to calculate the emission of the road from technical parameters like traffic flow, speed, road surface. The models used in noise calculations are quite different with respect to the parameters that are taken into account. Conservative empirical models describe the main influences like attenuation due to distance, diffraction and reflection with relatively simple algorithms. Some newer methods include ground reflections, meteorological effects and coherence effects.

The main tasks of road engineer today are: to think thoroughly about an optimal balance between wanted accuracy, necessary precision and transparency; to use and to improve recommendations for the further development or improvement of the existing calculation methods; to apply new methodologies and up-to-date techniques in the field of traffic noise research.

REFERENCES

1. WHO Guidelines for Community Noise: Berglund, B., Lindvall, T., Schwela, D.H. Guidelines for Community Noise, World Health Organisation, Geneva, 2000, p.XII.

2. Danish Environmental Protection Agency, www.vejdirektoratet.dk

3. RANCH project Internoise presentation, Babisch, W., 2006.

4. W. Probst: “No worries – how to handle acoustical planning problems with noise calculation software”, the materials of the 14^th International Congress on Sound and Vibration, Cairns, Australia, 9-12 July, 2007.

5. "SET - Sound Emission and Transmission", brochure published by DataKustik GmbH.

6. "CadnaA - Software for Environmental Noise", brochure published by DataKustik GmbH.

7. W. Probst, Comparison of the noise calculation methods for roads with other European methodologies, Federal Highway Research Institute, Germany.

8. W. Probst, Accuracy and precision of prediction models for road noise, the materials of the International Conference Euronoise 2009, Edinburgh, Scotland, October 26-28.

9. Brown AL and Macdonald GT. Australian journal of environmental management 2, pp. 65-77,2003.

10. Richard Barham Environmental noise monitoring, Mar 2011, www.aweimagazine.com.

11. Wolfgang Probst Comparison of noise prediction methods , 18^th International Congress of Sound and Vibration 10-14 jul 2011

12. K. Kumar1, V. K. Katiyar, M. Parida, and K. Rawat, Department of Mathematics, Mathematical modeling of road traffic noise prediction, IIT Roorkee, India-247667. Centre for transportation, department of civil engineering,17 sept 2010