Additional guidelines for the execution of tyre-road noise measurements with a CPX (Close Proximity) measurement trailer
de Roo, F.
The Dutch practice of assessment of the noise reducing properties of pavements according to the CPX (Close Proximity) Method has revealed that relatively large differences may occur between test results produced by different CPX operators. Due to these differences road authorities are facing questions and uncertainties about the acoustical quality of the pavements tested. In order to obtain a reliable picture of the actually existing differences between the test results of the various CPX trailers and the causes for these differences a comparison test between all CPX trailers in operation in The Netherlands was executed in autumn 2008 under assignment of CROW. According to the operators and / or producers all participating trailers satisfied the requirements and specifications of the current version of ISO/CD 11819-2 at that time. The results of this comparison test were analysed statistically and evaluated from the perspectives of acoustics and measuring technique . In autumn 2011 the comparison test was repeated  with the aim to update the research findings and to broaden the scope by inviting three participants from outside The Netherlands.
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Close proximity method
Physics & Electronics
II - Intelligent Imaging ; AS - Acoustics & Sonar
TS - Technical Sciences