6. Planning indications
 

 

6.2.1.3  Road and rail track surfaces

Road surfaces (fig. 6/1k) have an influence on the noise level. In accordance with RLS-90 the type of road surface determines the amount of noise level additions of up to 6 dB(A) (table 6/1). The higher the speed, the higher the potential surface-related noise additions. In the context of road planning this means that the paving of a play street or of a street in a 20 mph speed limit zone for example would be an appropriate means to influence the speed of the vehicles but, for noise abatement reasons, it would be unsuitable for reducing the driving speed on major roads.

Tests have shown that open-pored asphalt surfaces significantly reduce noise levels. Correction values for new road surfaces of DStrO = -5 dB are possible. Problems as for the physical life of these surfaces can be caused by their low durability and the gradual clogging of the pores due to tire particles and impurities. Figure 6/1m depicts this circumstance deduced from measurements separated into cars and trucks.

Heavy vehicles may cause vibrations and therefore substantial annoyances in the adjacent residential areas especially when driving on roads with an uneven surface. These annoyances are often intensified by sound level peaks caused by the throbbing sound of vehicle components or their cargo. Besides the average sound levels determined according to the calculation methods of RLS-90, there are peak levels caused by such events which can lead to annoyances.

As for rail traffic the traditional track structure consisting of a ballast bed and wooden sleepers is acoustically advantageous. Other constructions can lead to sound level additions of up to 5 dB (e.g. tracks embedded in streets). According to Schall 03 grass-covered tracks for trams reduce the noise level by 2 dB.

Further possible noise reduction measures for the wheel/rail system are:

  • grinding the rail surface for removing ripples

  • Srail web damping, especially in the case of tram tracks, by integrating the tracks into an elastic material or by covering them with grass
Road surface

Driving speed
19 mph
(30 km/h)		 25 mph
(40 km/h)		 > 31 mph
(> 50 km/h)		 > 37 mpg
(> 60 km/h)
Non-grooved mastic asphalt, asphalt concrete, stone mastic asphalt 0 0 0 -
Concrete or grooved mastic asphalt 1,0 1,5 2,0 -
Paving with an even surface 2,0 2,5 3,0 -
Other paving 3,0 4,5 6,0 -
Concrete pursuant to ZTV Beton 78 with steel brush, with longitudinal smoothing - - - 1,0
Concrete pursuant to ZTV Beton 78 without steel brush, with longitudinal smoothing, textured with burlap - - - -2,0
Asphalt concrete ≤ 0/11 and stone mastic asphalt 0/8 and 0/11 without loose chippings - - - -2,0
Open-pored asphalt surfacing with a void content of ≥ 15 % after construction, with grain size 0/11 - - - -4,0
Open-pored asphalt surfacing with a void content of ≥ 15 % after construction, with grain size 0/8 - - - -5,0

Table 6/1: Sound level additions DStrO in dB for different road surfaces depending on the driving speed
 

 

Fig. 6/1k: Road surfaces
 

Fig. 6/1l: Rail track surfaces with grass covering and low-noise track bed
 

Fig. 6/1m: Noise emissions (average maximum sound level of passing cars in a distance of 7.5 m) of free- flowing traffic,
source: Federal Environmen Agency
           
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