Low-noise road surfaces

Rolling noise from cars starts to exceed engine noise at just 25km/h. Low-noise road surfaces can reduce noise significantly. Unlike soundproof walls or windows, this restricts the amount of noise that is actually generated. The Federal Office for the Environment (FOEN) is involved in research into low-noise road surfaces and provides funding for them to be laid on urban roads.

The amount of rolling noise vehicles produce depends on the composition and construction of the road surface. The smaller the maximum aggregate size of an asphalt mix and the greater the surface’s air void content, the quieter the surface will be. Other crucial factors include how porous and elastic the surface is and how it is maintained.

Modern low-noise surfaces can reduce noise by around eight decibels when new and by around three decibels at the end of their service life. A reduction of three decibels is acoustically equivalent to halving the traffic volume. Officially, a surface is considered to be low-noise if it reduces noise by at least one decibel compared to a conventional surface at the end of its service life.

Excerpt from the video ‘Quiet road surfaces in the canton of Aargau’

Full video (3:37) available here.

Benefits of low-noise road surfaces

Laying low-noise surfaces is a highly effective way of reducing road noise at the source.
Thanks to the direct impact at the noise source, fewer interventions such as noise barriers or soundproof windows are required.
Low-noise surfaces not only reduce the overall noise level, they specifically reduce high frequencies, resulting in a more pleasant sound.
Low-noise surfaces benefit not just specific buildings, but entire surrounding neighbourhoods.
Traffic flows are not affected.

Best practice list

The best practice list contains information on low-noise surfaces that have been laid in Switzerland and their acoustic impact over several years. The list is updated regularly.

Liste der besten leisen Beläge innerorts in der Schweiz 4mm-6mm (PDF, 93 kB, 07.01.2020)

Liste der besten leisen Beläge innerorts in der Schweiz 8mm-11mm (PDF, 92 kB, 07.01.2020)

Combined noise protection measures: 30km/h speed limits and low-noise road surfaces

If speed limits are reduced from 50 to 30km/h on roads with conventional surfaces, the average noise level can be reduced by around 3dB(A). The additional effect of speed reductions is somewhat less pronounced on low-noise surfaces, however, because rolling noise volume is already significantly reduced by these surfaces.

Overall, a combination of these two measures lowers noise by around 5dB(A), although this figure varies depending on the composition of the traffic.

Wirkung kombinierter Lärmschutzmassnahmen Tempo 30 und lärmarme Strassenbeläge (PDF, 4 MB, 10.05.2022)Im Auftrag des Bundesamtes für Umwelt (BAFU).

Evaluation de l’effet sur le bruit de la limitation de vitesse de 50 km/h à 30 km/h et de la pose d’un revêtement phonoabsorbant (PDF, 2 MB, 09.05.2022)Im Auftrag des Bundesamtes für Umwelt (BAFU). (Nur auf französisch verfügbar.)

Life cycle assessment of low-noise road surfaces

In a full ecological assessment, low-noise surfaces prove more cost-effective than the reference surface over the entire life cycle of construction, maintenance, use, removal and disposal.

Lärmarme Strassenbeläge – Ökobilanz und Lebenszykluskosten (PDF, 3 MB, 08.03.2024)Im Auftrag des BAFU