Assessing the environmental impact exerted by roads in operative conditions - a Highway case-study

The work arises from the consideration that the environmental impact of a road cannot be limited to the analysis of materials constituting it, even if correctly analyzed in their life cycle, because roads are designed mainly to accomplish well established requests of transportation demand of people and freights. These considerations must be properly taken into account, when analysing the environmental performance of the road infrastructures, by properly accounting for the vehicles’ pollutant emissions. On the other hand, a given road is comprised of the pavement and subgrade; it also includes several different components and accessories (e.g. road marking, drainages, safety barriers, etc.) that contribute to set a road infrastructure in operative conditions. As a matter of fact, apparently, unlike pavement materials and traffic flow, only a limited attention has been paid in the scientific literature to roadside components. In the present work the environmental pressure of these components, and especially safety roadside installations (i.e. guardrails), is presented and critically compared with the one exerted by pavement materials and traffic flow, in order of establishing their relative contribution. To accomplish this task, an application referring to a segment of a typical Italian highway is proposed. By means of the inclusion of the other accessories, a general assessment of roads can be achieved, that is more useful for administrations for better matching the current sustainability standards and guidelines.