Methods to estimate efficiency of Low Noise Pavement for specific vehicle categories

Low Noise Pavements (LNPs) are efficient in reducing the rolling noise component of road-tire noise generation mechanisms. Open (porous) asphalt can be also efficient in reducing the propulsion noise component. As rolling/propulsion noise ratio varies with vehicles' category, the mitigation effect of a LNP varies between categories as confirmed by experimental data gathered in the LIFE NEREIDE. A proper model needs to predict and simulate the effects of LNPs in real conditions in the implementation sites. At present, LNPs can be modeled according to CNOSSOS-EU methodology using available reference surfaces, or by tuning user-defined surfaces. The paper discusses the limitations of mapping methods in delivering reliable values for specific vehicle categories, even when using ad-hoc tuned surfaces. The results are based on case studies in which modeling results are compared to experimental data. The study found that differences in measurements are due to the way the source model is conceived and cannot be completely eliminated.