Int CPX Trailer 531X150

Noise surveys (CPX)

Noise is an increasing problem for many people living next to heavily trafficked roads. Removing the traffic would result in very high costs, and thus the solution is to remove a considerable amount of the noise by means of a new low noise pavement. Sweco is now capable of measuring the effect of the noise reduction solutions.

Why should you measure?
Knowledge about what the effect of various noise reduction solutions will be can help you to select the right solutions for the area where a noise reduction would be needed.

Technical description
CPXmaalingcopyThe Close-Proximity Method (CPX) measures the noise emission from a standard passenger car tyre when rolling over a road surface. The CPX measurement is described in the ISO standard ISO/CD 11819-2 and is performed in accordance with this standard.

Sweco offers these measurements in cooperation with a Dutch company having a closed CPX trailer for measuring of roads and software for data treatment and presentation of the results.

Depending on speed limitations measurements are made at a constant speed of 50 km/h or 80 km/h. Normally, measurements are not performed at other speeds. In this way the option of comparison with other road sections is preserved.

The final result of the CPX measurement is a CPX noise level for the standard passenger car tyre and the truck tyre, respectively, and a common index (CPXI). This will be part of the final reporting where a conversion of CPX values to SPB values (Statistical Pass-By) is made on the basis of the CPX measurements made on Dutch reference sections. This is an expression of the average noise observed by a person at a distance of 7.5 meters from the centre of the road, when a vehicle passes by at a given speed.

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Int CPX Trailer 226X180


Bjarne Bylov Jensen
Bjarne Bylov Jensen
Head of PMC Sale & Market Department
+45 8228 1435


Jens Pedersen
Jens Pedersen
+45 8228 1490


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CPX Measurements