Methodology to evaluate the efficiency of additional devices on noise barriers

Due to the interest in reducing the noise quality in the vicinity of roads, it is very common to find anti-noise devices on their banks. The continuous growth of roads and vehicles have required the need to improve the effectiveness of barriers, putting on the barrier additional element called top device (cap, top barrier, crowning). This paper presents the first results obtained during the MAITE project "Transport infrastructure noise attenuation: design and system modelling of additional devices to optimize the effectiveness on diffraction edges", based on calculations to evaluate the effect of the top edge of the barrier. The Harmonoise reference model has been used to choose the propagation method for evaluating the diffraction effect either in the source region and receiver region. The intrinsic characteristics of sound diffraction of added devices have been assessed according to the European technical specification CENT/TS 1793-4. Finally, it is also presented the results obtained by numerical simulations using a Boundary element method, in order to verify the results achieved in the measurement campaign.