Traffic-related noise pollution accounts for over one million healthy years of life lost annually to ill health, disability or early death in the western countries of the European Region, states a WHO report on the subject. But this problem is not limited to Europe as it affects any country with traffic areas and high vehicle usage.
One of the biggest contributors to this issue is the sound created when a tyre touches the pavement. The worst type of tyre/road interaction occurs at speeds of, or above, 50 km/h. For light vehicles, it starts at speeds as slow as 30 km/h while, for the otherwise quiet electric vehicles, it happens at every speed range.
The United Nations Economic Commission for Europe has issued legal limits to control tyre noise and these are in place in most industrialized countries. However, road surfaces are also an important variable, influencing traffic noise as much as tyres and vehicles do.
A few countries have started to modify road surfaces in areas vulnerable to high noise, but there is still a long way to go. Negotiations are currently underway to legally limit how much noise a road surface should generate, a move that is also backed by vehicle and tyre manufacturers.
But in order to put these requirements into practice, we need International Standards to uniformly and reliably measure and monitor the influence of road surfaces on traffic noise. ISO published a first standard in 1997, but advances in technology and changing needs have led to the development of a new methodology in ISO 11819-2, Acoustics – Measurement of the influence of road surfaces on traffic noise – Part 2: The close-proximity method.
Ulf Sandberg, Project Leader for the new standard, says that “the new methodology is much more practical and easier to use, especially for long stretches of road”.
This new method led to the development of technical specification ISO/TS 11819-3 on reference tyres. Sandberg explains: “We were developing the new ISO 11819-2 when we realized that we also needed to identify tyres correctly to give reliable and reproducible data, so we created ISO/TS 11819-3.”
However, the ISO committee developing these standards went even further. Recent research has shown that temperature influences noise emission as much as tyres and road surface. A new document, ISO/TS 13471-1, was developed to account for the influence of temperature when measuring tyre/road noise.
“The need to control road noise is getting more and more attention. The European Commission, for example, now requires that member states regularly report traffic noise emission along major roads and that they develop abatement programmes if these are found to be excessive,” says Sandberg. “The three new documents offer a solid toolbox for identifying the contribution of road surfaces to noise pollution.”
The documents were developed by ISO technical committee ISO/TC 43, Acoustics, whose secretariat is held by DIN, ISO’s member for Germany.