Transportation infrastructures represent a relevant noise source in residential areas and have to be carefully taken into account in urban planning. Road traffic is commonly assumed to be the most relevant transportation mean in developed countries. For this reason, road traffic noise can be considered as the most important source of annoyance. The extremely random nature of road traffic makes very difficult to model the phenomenon and give reliable predictions. In the infrastructure design phase, a proper acoustic modelling can be helpful to minimize the noise impact. If the road is already present in the area, it is important to design effective mitigation actions. In this paper, the installation of noise barriers is simulated in a case study. This location, in south Italy, is characterized by several buildings placed in proximity of a motorway. In particular, a new building set has been built just in front of the motorway, without providing any noise mitigation action. In this paper, once the noise map of the area is obtained with a predictive software, the effects of the barriers, measured in terms of noise level reduction, are evaluated by means of literature, regulation and software approaches. The comparison between these approaches will be discussed and will show that, in order to obtain a reliable estimation of the noise reduction, diffraction, reflection and other relevant parameters cannot be neglected
