Venditti A., Coppi M.

Acoustic pollution problem, determined by metropolitan lines, results particularly meaningful in the surface lines where it determines on the surrounding receptors, superior or comparable noise levels with those products from the urban traffic. To attenuate the acoustic impact is not always possible to realize appropriated antinoise barriers, for aesthetical motives and for structural motives. To reduce noise is opportune to do some interventions less invades to attenuate the noise in proximity of the contact wheel-railway, in consideration of the fact that the noise produced by the transit of the convoy is primarily due to the contact wheel-railway. In the text it is exposed a project of an acoustic resonator to attenuate the noise produced by the contact wheel-railway of the metropolitan convoy. Spectrum of emission of the metropolitan convoy, valued experimentally in proximity of the railway, introduces a maximum of emission around 350 Hz. It was designed an acoustic resonator tuned on such interval of frequencies using the space between the safety way and the support plan of the railway line. The value of the coefficient of absorption of the acoustic resonator has experimentally been verified, using a prototype purposely realized reproducing the real situation in work.