Matching directive 2015/996/{EC} (CNOSSOS-EU) and the French emission model for road pavements

Abstract

The member states of the EU will have to implement CNOSSOS-EU from 01.01.2019 on. This requires to adapt existing emission databases to this new framework. In particular, road pavements are often country specific. CNOSSOS-EU offers a set of 9 coefficients per vehicle category to account for a particular pavement but with little guidance about how to tune these coefficients. In the French context, the noise emission model for road traffic was updated in 2009 in relation to the publication of NMPB 2008. It is based on a large database of statistical pass-by measurements on a representative set of national pavement formulations for the two categories of light and heavy vehicles. The emssion model introduces a classification in 6 categories {R1, R2, R3} x {Drainage, Non Drainage} that is extensively used in the context of strategic noise mapping. Since the propagation part of CNOSSOS- EU is very close to NMPB 2008, the approach taken here for a particular pavement formulation is to match sound power levels and adjust the available 9 coefficients so that the discrepancy is as small as possible. Although they both combine an engine noise component and a rolling noise component the emission models of CNOSSOS-EU and NMPB 2008 differ significantly in terms of formulation and input parameters. Therefore an exact analytical resolution was not possible and simplifying assumptions were necessary. Moreover, the focus was put on aged pavements on horizontal roads. In addition, we considered only steady speeds above 50 km/h. The results presented illustrate that with the coefficients obtained, a good agreement is observed on LAw both for CNOSSOS-EU category 1 and 3, with discrepancies lower than 1 dB(A) in most of the cases. The procedure works better on Non Drainage than on Drainage pavements.