Strong noise reduction through the combination of low-noise pavements and speed reductions

Noise protection at the source

To reduce noise pollution, it is usually most effective and useful to reduce noise at the source. In the case of road noise, measures such as the use of low-noise pavements or speed reductions can be used for this purpose. However, these individual measures are often not sufficient to achieve the noise protection targets in locations with high noise pollution. An extensive measurement campaign conducted by G+P on behalf of the FOEN shows that an even greater reduction in noise can be achieved by combining these two measures in order to effectively protect the population from excessive road noise.

Proof of the effectiveness of low-noise pavements AND 30 km/h speed limit

In cooperation with the canton of Aargau, G+P implemented a unique measurement concept at five locations in summer 2020: On carefully selected stretches with existing SDA pavement (= low-noise pavement), extensive measurements of noise immissions, traffic composition and effective speeds were carried out over one to two weeks. In the process, the signalised speed was reduced from 50 km/h to 30 km/h over at least three days. On another stretch in the city of Lucerne with conventional asphalt, reference measurements could be carried out thanks to a permanent re-signalling that was planned anyway. This made it possible to measure under real conditions which road noise emissions really show up in practice.

Based on this traffic-normalised data basis, we developed an empirical calculation method to estimate the noise effect of a speed reduction on already low-noise SDA pavements.

Estimation of the noise effect by means of look-up tables

The data analyses have clearly shown: The effect is strongly dependent on the actual speed driven on the respective road section as well as the traffic composition. In the final report, we therefore provide reference tables that show at a glance which effect can be predicted depending on the influencing factors.

Tool for the practice

If excessive noise pollution is detected on a road section, the tools developed can be used to determine how great the expected noise effect is. Thus, in addition to the effect of a low-noise pavement of 3 dB, a speed reduction from 50 to 30 km/h can be expected to reduce noise by 2.3 dB ± 0.4 dB (N2 share 6%). Compared to the scenario without noise abatement measures, a noise reduction of 5.3 dB is thus possible in the above example, which corresponds to a perceived reduction in traffic volume of over 70%.

This study, based on long-term acoustic measurements, lays the foundation for the planning and application of combined noise abatement measures. This combination of speed reduction and noise abatement measures helps to further reduce noise pollution.

On this FOEN page you will find more information about our study on the combined effect of speed reduction on low-noise pavements:

https://www.bafu.admin.ch/ - Measures against road noise

And via this link you can download the report of the study incl. reference tables of the noise effects as a PDF document.

Final report - Combined effect of 30 km/h and low-noise pavement

Acknowledgement

We at Grolimund + Partner AG would like to thank the Federal Office for the Environment (FOEN) for allowing us to carry out this exciting study. We would also like to thank the Civil Engineering Office of the Canton of Aargau, which enabled us to implement this unique measurement concept under real conditions.