Acoustic contamination

The main sources of noise in cities and other settlements are motor transport, railway and air transport and industrial plants. The motor transport creates the noise level from 82 to 95 dBA on the streets. The street noise level is determined by intensity, speed and character of traffic, and also depends on the construction factors (structure of the streets, height and density of buildings), road cover and green plantings. On the territory of industrial cities cars make significant noise level, which spreading over the territory close to roads gets into dwellings. There following methods for reduction of noise influence on environment are recommended: decreasing of traffic speed and its restriction for some types of cars on certain roads in definite time; motor transport development; improvement of buildings soundproofing and construction of noise struggling screens along high-ways.

Significant noise level is created by the railway transport: the electrotrain - 93 dBA, passenger train - 91 dBA, freight train -92 dBA on distance of 7,5 m from the moving train. Noise levels in subway open lines reaches 70-80 dBA. The most noisy among all the types of the city transport is tram. The moving tram creates noise loading (10 dBA higher than car wheels) when engine is on and doors operating. Reduсtion of tram noise level is possible improving condition of tram-line, and also modification of car construction.

The air transport creates sound equivalent to levels of 80 dBA, and maximum level reaches 108 dBA. For noise minimizing special piloting on takeoff and landing, more steep trajectories, low power setting, rational organization of air movement (take-off and landing strip not crossing localities), rational planning etc are used.

Normalization of noise for city building is carried out in correspondence with the standard «СНиП: Защита от шума». For example, for apartments and rooms norm makes 30 dBA, class rooms - 40 dBA. These norms are indicated for night time (from 11 p.m. to 7 a.m.), and in day time norms are increased for 10 dBA.

City-planning measures on noise reduction include: increasing of distance between protected object and source of a noise; using of acoustic screens - slopes, walls, screen-structures; rational placing noisy and protected objects; using earth relief, deepening of highways; using free building construction (places where people stay temporarily: shops, dining rooms, ateliers serve as screen-building situated in front of the streets and apartment houses are placed behind them); trees planting.