Road traffic noise affects a large number of people in Switzerland, especially in cities and conurbations. Despite improvements in protective measures, road noise remains a challenge to health and quality of life and generates external costs of around CHF 2 billion a year.
Around 740,000 people in Switzerland are affected by road traffic noise exceeding the limit values, particularly in urban areas. This constant exposure leads to stress, which can cause serious illness, and generates considerable costs. If noise limit values are exceeded, the federal government, cantons or communes are obliged to take action and improve their roads.
The Environmental Protection Act (EPA) and the Noise Abatement Ordinance (NAO) prioritise measures to counteract noise at its source. This approach ensures that noise is reduced right at the point of origin. Priority is therefore given to measures such as low-noise road surfaces and speed restrictions. Lower speeds reduce rolling noise, and the cavities in low-noise surfaces absorb part of the sound. This is important, because rolling noise from cars starts to exceed engine noise at just 25 km/h.
Since 1985, more than CHF 5 billion has been invested in road improvements, protecting over 380,000 people from road noise exceeding the limit values. For main roads and other roads, around 900,000 people had benefited from noise protection measures by 2023. However, a large number of people are still affected by road traffic noise exceeding the limit values. Noise reduction is an ongoing task. The federal government provides the cantons with financial support.
Above approx. 25km/h, rolling noise is the main source of noise from cars. It occurs when the wheels roll over the road surface and start to vibrate. Modern low-noise surfaces have a fine top layer and a special porous structure consisting of large cavities that absorb the noise. When new, they can reduce noise by up to nine decibels, and by at least three decibels over the long term.
30 km/h speed limit lowers noise emissions by around three decibels compared to a 50km/h speed limit, a reduction that equates to halving the amount of traffic. This measure is particularly effective because it also significantly reduces disruptive noise peaks and calms traffic flows.
Quiet tyres can reduce noise by around two decibels. Mandatory tyre labelling, which was introduced in 2014, makes noise emissions for each product clearly visible, enabling consumers to make informed choices.
The protective potential of each noise-reduction measure needs to be examined in detail before the right solutions can be promoted. To this end, various scenarios for noise reduction at source have been analysed. Current evaluations show that restricting speeds to 30 km/h in urban areas offers the greatest potential for noise reduction, protecting around 70% of residents from excessive noise. If measures are combined, the potential for noise reduction is even greater.
Traffic regulations state that drivers must not generate any avoidable noise. Considerate use of vehicles, especially in inhabited areas, helps to avoid inconveniencing nearby residents. At low speeds, the main noise source is the engine. Drivers can therefore reduce the noise they generate by modifying their driving style.
Vehicles must not exceed the technically avoidable level of noise. For this reason, unnecessary noise-increasing vehicle modifications for example, to their exhausts are prohibited.
