EU Project SPENS: Typical Pavements in European New Member States and Repeatability of CPX-Measurements

Low-noise pavements are, in combination with noise barriers, a very important measure to reduce road traffic noise and to protect the population living near the road infrastructure. In order to develop low-noise pavements test methods to quickly assess the noise emission properties of the surfaces have been standardized. The draft standard ISO/CD 11819-2 (CPX, Close-ProXimity) presents a flexible method based on trailer measurements of the near-field noise emitted by a set of two to four test tyres. Recently a new tyre has been introduced into the measurement set and working group 33 of ISO TC43/SC1 is now reviewing this draft standard. During the summer of 2008 arsenal research has carried out CPX measurements at ten different locations in three different European countries (Slovenia, Slovakia and Czech Republic). This research focused especially on the typical pavements in the EU New Member States (stone mastic asphalt and asphalt concrete with 8 and 11 mm chipping size) and on the noise emission of the new ASTM tyre in comparison to the previous standard tyre. This re-search has been carried out within the EU project SPENS (Sustainable Pavements for Euro-pean New member States). The main topic of the present paper is the repeatability of the CPX measurements using different tyres (A, D and ASTM). The measurements have been performed at three different locations on three different surfaces driving five times with each tyre. A statistical analysis has been carried out for the three different tyres concerning the overall levels and the frequency spectra. The paper will conclude with some remarks on the usefulness of the new ASTM tyre as test tyre for CPX measurements.