Characterization of tire-road noise from Brazilian roads using the CPX trailer method

Abstract Traffic noise is an important area of research in several countries, since it can present a significant environmental health problem. Brazil is currently considered a country with extremely high vehicular noise levels and yet there is currently no specific legislation to reduce traffic noise. Also, with regard to data on the sound pressure levels of highways, acoustic reference levels are non-existent. The aim of this study was to characterize the noise levels of Brazilian highways (specifically in the state of Santa Catarina) with six different types of pavements and textures (dense-graded asphalt mix, dense-graded rubberized asphalt mix, porous friction layer, gap-graded asphalt mix, micro-coating asphalt, rigid concrete pavement) using the first tire-road measurement trailer developed in Brazil and applying the close proximity (CPX) method. The results indicate that the porous friction layer has the lowest noise index ( CPXI ) when compared to the other pavements studied. In the tests carried out with the CPX trailer on the rigid pavements there was no significant difference between the results for the final CPXI values. The measurements taken with the CPX trailer and the sand patch method showed that the macro-texture of dense mixes has a notable influence on the generation of mechanical noise. Statistical correlations between the results obtained with the CPX, CPB and sand patch methods are reported herein and the data show that it is possible to predict the tire-road noise emission as a function of distance.