Guidelines for the "euphonic" road infrastructures project

Increasing environmental awareness has made it necessary to plan new civil engineering projects according to sustainable development criteria. As regards the more specific case of transport infrastructures, the major environmental impact of roads is, undoubtedly, that caused by traffic noise. Obviously, the simple physical distancing of the sensitive receptors most exposed to the sources of noise is in itself a sure method of self-mitigation. However, it is clear that the hypothesis of direct physical distancing between source and receptors is impractical both for economic reasons (costs of expropriation) and the scantiness of non-urbanised territories bordering with the infrastructures. Any analysis of the phenomenon of acoustic impact must also include discussion on the need to extend the width of the strip pertaining to road noise, which is currently on the agendas of governments in Europe and other parts of the world. In Italy, for example, a recent government decree has laid down the widths of noise-abatement strips (varying from 250 m for major extra-urban roads and motorways, to 30 m for urban and local roads), extending the width of the limit of the true territorial impact of transport infrastructures. Therefore, the aim in the near future must be to project road infrastructures with “euphonic characteristics”, acting both on road geometry (sections in a natural or artificial cutting, tunnels, etc.) and materials (eco-technical, sound-absorbing, euphonic pavements, etc.). The goal may be more easily reached once the roadside strips are included within the concept of “road”, with the potential to mitigate the environmental impact of the infrastructure itself. A “widened road system” can be reasonably referred to, no longer means just the roadway but also strips of land of an adequate width on either side of the infrastructure, with truly self-mitigating characteristics with respect to the local environmental context. This discussion also covers the debate on the renewal of anti-noise systems for road infrastructures, specifically oriented towards minimising the environmental impact of the actual noise abatement systems and aimed at systematically increasing the sustainability of the new transport infrastructures during the preliminary project level.