Sonic crystal noise barrier design to reduce railway noise emissions

International audience; In the heart of a tense competitive context, railway transport has a major advantage through its low environmental impacts. Among these, particular attention is paid to acoustic emissions. For people living near railway infrastructures, noise emissions are a major concern. Noise barriers are an effective and traditionally implemented solution to reduce the acoustic impact of railway traffic. Nevertheless, these barriers are generally not well accepted by the population for aesthetic reasons. Sonic crystals are structures that provide significant acoustic attenuation, particularly around certain frequencies (so-called ?band gaps?). Using this new type of noise mitigation solution has advantages in terms of integration into the landscape and cost but remains a challenge given the plurality of railway acoustic sources, both in terms of their location, directivity and spectral content. This study presents results obtained by 2D Finite Element Method (FEM). This paper has two objectives. The first one is to study the sensitivity of acoustic performance to geometric parameters such as the filling factor or the shape of the elementary structure of the crystal. The second seeks to design a sonic crystal adapted to each type of railway source (rolling, equipment, aeroacoustics) - which differ from each other in their sound emission spectrum. A comparison with a full classic screen is also presented.