Traffic Noise 1993
It can be seen from the map that the traffic on the main network roads causes a very high noise load.
In Table 3, the length of the effected built-up roadsides or their percentage of the overall length is shown for each volume level.
During the day load levels between 65 and 70 dB(A) occur most frequently: about 760 km, that is 42 %, lie in this volume range.
Extreme loads over 80 dB(A) were measured for one segment a kilometer long (0.1 %). If one sets a basic level of 65 dB(A), which can be seen, according to current noise research, as the threshold for increased heart attack risk (c.f. Ising et al. 1997), then 1,270 km of built-up roadsides, or 70 %, could be seen as excessively polluted.
The following situation applies at night: The emphasis lies in the volume level from 55 to 60 dB(A), namely 658 km or approx. 36 %.
Levels exceeding 75 dB(A) only occur seldom. More than 1,478 km, or about 82 %, carry a load of more than 55 dB(A).
High traffic noise loads are caused not only by high traffic volume but, by very narrow streets with closed roadside construction on both sides. A substantial increase in volume level (up to 5 dB) is induced through cobblestone or heavily damaged road surfaces. In the eastern boroughs of the city, the tram often contributes to the night volume level. Table 4 gives an overview of street segments with unusually high noise loads.
The level of the mean volume in a street does not permit an opinion as to whether this constitutes an important noise problem for the population. The number of effected residents is significant for an interpretation of the load data. It is essential to consider the number of directly effected residents when setting truck night driving prohibitions, selecting detour routes, and routes for heavy transport traffic, and priorities for noise abatement measures, etc..
For this reason, an estimation of the number of residents directly effected by traffic noise, together with a probability factor for their actual presence, was made for each acoustically tested road segment.
This effected persons potential in the close range to the tested streets is shown in Table 5 according to the individual volume level classes.
If one assumes again that the daytime limit of 65 dB(A) for an increased heart attack risk when interpreting this table, then approx. 70 % of effected residents, or about 168,000, are subject to excessive loads.
Approximately 24,500 residents, or 10 %, are even subjected to levels exceeding 65 dB(A) at night. This requires priority action.
In order to deal with this hazard, a volume reduction of up to 15 dB(A) would be necessary.
Such a load reduction can only be achieved over the long term – if at all. Although technical development can lead to a decrease in motor and motion noises, the long life of motor vehicles as well as the limited financial resources for repair and modernization of road services will only allow these changes to be noticed far into the future.
A radical reduction in motor vehicle traffic – a reduction by 50 % would lead to a drop of 3 dB(A) – cannot be expected.
Measures such as speed reduction, night driving prohibitions for trucks, user preferences for low noise trucks, improvement of local public transport, promoting the attractiveness of bicycle and pedestrian traffic could altogether lead to a lower noise load. The effects are relatively low and – as to be expected – they are comparatively minimal and in part defy quantification.
To protect the health of the effected residents in highly polluted streets, the installation of windows with noise reduction insulation (as necessary, with integrated ventilation elements) should be accelerated. This is also the responsibility of owners and lessors of apartments.