CNOSSOS-EU coefficients for electric vehicle noise emission

Abstract

Road traffic noise mapping is a fundamental step in the prevention and mitigation of citizens' exposure to noise, which is the cause of well-known and widespread health issues. The most current noise simulation models are not yet ready to adapt to the present and future scenarios of sustainable mobility, manifested by the increasing of electric vehicles. To improve the accuracy of the simulated noise level results, the European CNOSSOS-EU model uses different calculation coefficients for the sound power for each car category. However, for electric vehicles (EVs), such coefficients have not been defined yet, and it is deliberately left open in the decree pending studies dedicated to their definition. In order to fill this gap, the present study defines the CNOSSOS-EU coefficients for calculating the sound power of EVs starting from the Controlled Pass-By measurements in a real case scenario. The analysis performed with four different EVs, considering two different pair of tyres and two different pavements such as reference (RP) and crumb rubber (CRP). A peculiarity of the work is that measurements were deliberately carried out in urban roads since they represent the case where the road traffic noise maps will be used the most to investigate citizens’ exposure to noise. However, this real case scenario implied measurement difficulties which required a specific adaptation of the data analysis procedure. The results are compared with similar studies thus defining values that can be taken as a reference in road noise simulations. Results are the coefficients for the open category (category 5) of CNOSSOS-EU for both RP and CRP, but also a methodology applicable into urban area under real conditions that could act as a basis for other future studies aimed at broadening its applicability and statistical value.