Venditti A., Coppi M.

Acoustic pollution problem determined by metropolitan lines is particularly evident in the uncovered places in proximity of the entrances in gallery. This is due to that the presence of the gallery income determines an increase of the due sound emission to the field reverberated in the gallery (effect of income) that it contributes in substantial way to the acoustic pollution on the surrounding areas. About the simulation of the acoustic impact produced in the uncovered places in proximity of the entrances in gallery, it is necessary to consider within the projects of improvement in the acoustic characterization of the source, besides the direct emissions, also the contribution determined by the field reverberated inside the gallery. To such purpose, a method has been elaborate to simplify the evaluation of the income effect through the introduction of a specific virtual source based on acoustic and dimensional characteristics of the galleries. The theoretical results have been confirmed with specific reliefs performed on the site. The method is described in the text, based on the sizing of the virtual source to introduce in the simulation of the acoustic impact determined by the metropolitan lines in the uncovered places in proximity of the income in gallery.