Traffic Noise in Green and Open Spaces 1992
Especially strong and large-scale infringements of the target value of 55 dB(A) specified by the German Industrial Standard (DIN) 18005 occur in the area of the Avus freeway. In this case, the noise pollution results significantly from a rush-hour corridor. Due to a network of main traffic arteries, the Tiergarten is affected by noise pollution, especially in the area of the Grosser Stern. In both cases, free sound propagation exists without significant decreases in level due to screening. The Treptow Park, too, is extensively affected by traffic noise, which is associated with a considerable decrease of the recreational value.
Because of the physically entailed characteristics of sound propagation, courses of isophonic lines which are difficult to understand can occur, particularly behind screening facilities. For the consideration and interpretation of this, the following points are to be primarily considered:
Screening arrangements (noise prevention walls, closed rows of houses etc.) are especially effective in the proximity zone. In some few areas, the green and open spaces are protected by buildings located in front, toward the traffic noise. Although a closed roadside development with high houses on both sides means major noise pollution for the street area and/or for the roadside developments themselves, the acoustical advantage of a closed roadside development facing an open development for the behind it lying green and open spaces shows itself here. Due to the closed roadside development with four-story apartment houses (that corresponds to an amount of 15 to 20 m) can be decreased the noise pollution of the behind it lying areas large-area around up to 20 dB(A) (e.g. in the Hasenheide park).
Noise prevention wound display against it relatively slight wall amounts of up to 5 m. Still level decreases can be reached with these noise prevention arrangements in the distance up to 300 m of the street middle still by 10 – 15 dB(A).
- The distance-conditional level decrease in the distance radius of 50 – 1,000 m of the axis of a long street totals about 4 dB(A) per distance doubling. If one departs for instance at an excursion through the Grunewald of 50 on 100 m distance from the middle of the Avus freeway, to reach so sinks the perceived noise level around approx. 4 dB(A). Around a further decrease of the noise level by 4 dB(A), the hiker must depart around in addition 100 m of the Avus freeway up to a distance from 200 m. An approximating or removing from the highway around 100 m in the distance radius of 800 m leads against it for a lifting and/or layering of the noise level around approx. 1 dB(A), which as volume change with the human ear hardly is to be perceived. Because of these expansion conditions the calculated isophone lie nearby from streets more densely together, and in larger distances prevail uniform noise pollution, which are marked by a constant color on the map.
Altogether becomes clear, that the majority of the inner-city recreational areas and large parts of the forests serving as urban recreation areas are hurt in the outside area considerably by the motor vehicle noise. If one compares the noise values with the orientation value the German Industrial Standard (DIN) 18005 from 55 dB(A), shows itself, that this value is overstepped in all green spaces in the area of the internal city rail circle line partly considerably. With it the there anyhow bad quantitative provision is hurt with green and open spaces in addition in their quality clearly.