Methods of combating with noise pollution in zones influence of large cities

Abstract

The main sources of external noise in cities are: streams of all types of land road and rail transport; aviation transport at airports and zones of air routes of aerodromes; industrial enterprises and individual equipment; playgrounds of loading and unloading works objects of transport, trade, municipal and other enterprises and establishments; outdoor sports facilities and playgrounds; machines, mechanisms and technological equipment that perform construction, repair, cleaning and improvement of urban areas. Traffic flows on main streets and roads and  trains are considered as linear sources of external noise in cities and all others as local. Due to the increase the level of motorization in Ukraine there is a problem of noise insulation and dust protection of buildings and structures located on roads of different purposes. Excessive noise can lead not only to physical discomforts but also to serious health problems, most commonly nervous system problems, cardiovascular disease, vision problems and increased fatigue. Transport noise contamination continues to increase with the growth of cities, urban population density, and the intensity of transport. Unfortunately, already today the noise level on the main highways of the cities is about 90 dB, which is already higher than the norm, and this level is increased annually by 0.5 dB.

It is impossible to completely reduce the noise level, but there are different methods to absorb it or to minimize it. They use different methods of sound insulation, one of which is the installation of noise shields. Depending of the principle of action, there are three main types of acoustic screens: absorbent, reflective, combined. According to the purpose, they are made of different materials, depending on which the screens can be transparent and opaque. Protective fences are constructed from materials with a high reflectance of sound wave energy. For this use: polycarbonate, glass, and rarely - concrete. Often, these materials combine. In the article is described the classification of acoustic screens according to the principle of action and presented a comparative characteristic of the noise absorption of materials used in the manufacture of acoustic screens.