COMPARATIVE STUDY OF Ld SOUND LEVELS FROM ROAD TRAFFIC NOISE IN COTONOU: IN SITU MEASUREMENT AND SIMULATION USING THE CNOSSOS-EU MODEL

Road traffic noise represents a major source of environmental nuisance in rapidly growing urban areas. This study analyzes the performance of the CNOSSOS-EU acoustic model in estimating the Ld indicator, through a comparison between in situ acoustic measurements and numerical simulations conducted in the city of Cotonou. Measurement campaigns were carried out on several roadways characterized by varying traffic levels, while the corresponding sound levels were simulated using the CNOSSOS-EU model, incorporating parameters related to traffic, road geometry, and the built environment. The results reveal a parallel trend between measured and simulated values of the Ld indicator, indicating that the model correctly reproduces the spatial patterns of road traffic noise. Nevertheless, a systematic overestimation of sound levels by the model compared to experimental measurements is observed, with discrepancies dependent on the local characteristics of the study sites. These results underscore the relevance of the CNOSSOS-EU model for comparative analyses and urban road noise mapping, while highlighting the need for local adjustments to improve estimation accuracy in the urban context of Cotonou.