Traffic Noise in Green and Open Spaces 1992

Methodology

The evaluation level was calculated for the selected areas and shown on the map in color, with a 5 dB(A)-graduation. The only source used for the noise pollution was the data on the motor vehicle and streetcar traffic of the main traffic arteries. Other noise sources, such as the traffic of the side-street network, the rail traffic of the city rail system, the subway and the Federal Railway, air traffic, and industrial and commercial noise, were not considered.

The evaluation level shown on the map was ascertained for the motor vehicle traffic on the basis of the “Guidelines for Noise Prevention on Streets” (RLS-90) and for the streetcar traffic on the basis of the “Guidelines for the Calculation of the Noise Pollution of Rail Traffic” (Schall 03).

For the calculation of the evaluation level, the mean levels were added for motor vehicles and streetcars. Thus, the streetcar noise was fully integrated into the calculation. The allowance of 5 dB(A) for rail traffic (“rail bonus”), which is contained in some guidelines and norms, is not utilized on streetcar noises in the inner-city area. Start-up and braking processes of vehicles at traffic-light-regulated intersections were arrived at by a distance-dependent addition of up to 3 dB(A) into the calculation of the evaluation level.

The calculations were undertaken for the mean ear height of a standing person (about 1.6 m), taking into consideration such large-scale screens as roadside developments, noise-prevention walls or extended mounds. For a lying person small-scale screening and increased floor insulation can result in up to 10 dB(A) less noise pollution.

The basis of the calculation is the average daily traffic volume mean for all days of a year. In addition to that, a day-time mean is calculated for the time from 6 AM – 10 PM, in order to determine the evaluation of the level per day. The evaluation level thus provides a year-round median value for the time between 6 AM and 10 PM. Particularly on Sundays and holidays, lower levels of noise pollution can occur, because of generally decreased flows of traffic, as is shown on the map. Streets which serve predominantly weekend traffic can, however, show higher noise pollution levels on Sundays and on holidays.

Because of the non-consideration of the side-street network (for this, no data exist from traffic counts), significant deviations of the calculated evaluation level from the actual noise pollution level may occur, particularly in the areas shown as having slight noise pollution (less than 45dB(A)).

Fig. 3: Evaluation Levels Depending on the Distance from the Street Axis, for Various Traffic Volumes (DTV), Given Free Sound Propagation and a Truck Proportion of 5%. (The hourly traffic volume decisive for the calculation amounts to 6% of the DTV.)

By way of elucidation, the distance-dependent evaluation level is shown in Figure 3 for ear-level on a long, straight street at free sound propagation, for various average daily traffic volumes. The display also covers very lightly traveled (DTV = 1,000 motor vehicles/24 h) and heavily traveled (DTV = 10,000 motor vehicles/24 h) streets of the side-street network, which were considered for the map.

At a traffic volume of 1,000 motor vehicles/24h, the evaluation level at 10 m distance is approx. 57 dB(A), and at 50-plus m distance, it is approx. 46 dB(A). This means that, due to the generalization undertaken for the map, even consideration of side-streets with a DTV of less than 1,000 motor vehicles/24h no would yield no other rating for the park. This is different, however, in the case of more typical side-streets, which are on as a rule traveled more heavily. Even at a traffic volume of 10,000 motor vehicles/24h, far-reaching noise pollution occurs on adjacent green spaces. Here, the evaluation level totals at a 50 m distance are still 56 dB(A); an inclusion of this side-street would thus yield a changed display of the affected areas of the adjacent green spaces on the map.

As a rule one can proceed on the assumption that the noise of these side-streets effects the green spaces to a depth of about 50 – 250 m, and causes a evaluation level of approx. 45-50 dB(A).

Small-area effective screenings (e.g. behind rotundas or small embankments) can cause lower evaluation levels in some cases than those indicated on the map. These lower evaluation levels, like higher evaluation levels in direct street proximity, cannot be shown at the present scale. The scale allows for a color-resolution of at least 50 m. Therefore, the color value indicated on the maps directly at the street describes the evaluation level at 50 m distance from the street. In the pedestrian area of the street, the evaluation levels can therefore be up to 10 dB(A) above the value indicated on the map.

The main traffic arteries, which provides the basis for the calculation of the noise in the open spaces, is shown on the map separately, with the calculated evaluation levels. The mean evaluation level of the streets is the averaged evaluation level of both sides of the street at the building edge. For street segments without development on both sides, the level at the roadside has been given. The values serve here solely for the orientation of the street segments and their sound levels which are the basis for the calculation of the noise in the open spaces. A more differentiated and more current representation of noise in built-up areas is found on Map 07.02 (SenStadtUm).

In addition, the noise prevention areas of the airports are marked on the map. In addition to the noise pollution of the open spaces due to the motor vehicle -traffic, which is shown, there is also noise pollution in the affected areas due to air traffic. A simple addition of the both sources of the noise is not permissible, however. For the Gatow and Tempelhof airports, no aircraft noise protection zones have up to now been ascertained. The presented protection zones of the Schönefeld Airport are of preliminary character and have not yet finally established (cf. State Development Corporation for Urban Development, Housing and Transportation of the State of Brandenburg 1994). By contrast, the noise prevention area of the Tegel Airport is legally defined and mandated by means ordinance.