The study of the environmental impact of urban railways mainly regards the noise generated by trains. Italian standards provide for the characterization of territorial pertinence zones (from the outer center line and for each side of the railway tracks), inside which specific absolute limit values of noise introduction produced by the same infrastructure are permitted. Therefore, according to provisions in these areas, the noise evaluation has to be performed referring only to the infrastructure contribution, without evaluating other acoustic sources in the same areas. As a consequence, in the pertinence zones the imposed limits for the infrastructure presence and the limits imposed by the acoustic municipal zoning, taking into account the acoustic impact of the other sources, are valid simultaneously but separately when evaluating the acoustic impact. However, in these areas the general acoustic climate is due to the overlap of both acoustic classes, and the noise induced on the population is determined by the contemporary presence of both sources. It is eventually very important to evaluate the effective noise dose absorbed by the population, especially when having to design mitigation interventions.