The Netherlands commissions SGS to develop an ultra-silent road surface to reduce noise pollution.

Recent changes in legislation on noise pollution of the primary road network in the Netherlands require measures to be taken within five years to limit noise levels around major cities. Other countries, such as Belgium, Germany, Qatar, Japan and the US, are facing similar issues.

Noise Reduction

Rijkswaterstaat, part of the Dutch Ministry of Infrastructure and the Environment, is responsible for the design, construction, management and maintenance of the main infrastructure facilities in the Netherlands.

After exploring common solutions, such as noise barriers, tunnels and reducing the speed limit, Rijkswaterstaat found that the options are often expensive, aesthetically undesirable or take too long to implement.

Noise control at the source, by means of reducing the speed limit is unwanted from a user point of view. For Rijkswaterstaat, a more appealing form of noise control was to find ways to make the road absorb a large part of the noise.

As a result, Rijkswaterstaat issued a call for the development of an ultra-silent road surface with a noise reduction of 10 dB(A) and a service life of at least seven years.

Thanks to their expertise in innovative infrastructure and road construction solutions, SGS was among three companies, awarded the tender to develop a new road surface.

Ultra-Silent Road Surfaces

In January 2014 SGS started the development of PERSIST – an the ultra-silent road surface. Just one year later, PERSIST is the only concept in the Netherlands that comes close to Rijkswaterstaat’s requirements.

Promising Results

Acoustic consultants M+P tested two types of PERSIST. The tests show simulated noise reductions of 8.2 dB(A) and 9.5 dB(A) compared to standard non-porous asphalt. Furthermore, M+P is convinced the 8.2 dB(A) alternative can be improved to reach up to 9.1 dB(A).

Delft University of Technology performed a mechanical performance-screening test on the same samples tested by M+P. The tested samples are not only quiet, but also perform very well on skid resistance and resistance to raveling.

The skid resistance of PERSIST is as high as traditional open asphalt (ZOAB) and stone mastic asphalt (SMA). The cyclic wear test showed skid resistance of PERSIST to be higher than traditional asphalt alternatives. On these points, results indicate that PERSIST performs better than standard road surfaces.

Later this year Delft University will quantify the performance of the common asphalt types in the same test, so that the results can be compared one-on-one.

Additional Research, Improvements and Up-Scaling

The test results show that PERSIST is currently the best ultra-silent road surface in the Netherlands. This year InfraQuest – Rijkswaterstaat, TNO and Delft University of Technology – will perform many more tests on PERSIST and its individual components. These tests should also give insight into PERSIST’s performance on water ingress, resistance to UV radiation and performance in freeze-thaw cycles.

Parallel to the extensive test program of InfraQuest, Rijkswaterstaat and SGS will work on the next phase of the project: up-scaling to semi-field trials.

When testing is concluded, further upscaling to full field trials in public roads is expected. In the meantime, SGS is exploring the possibilities for the application of PERSIST abroad.

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