The S.S. 23 "del Sestriere" national highway has a role of primary importance in the Olympic event insofar as it allows, along with the S.S. 24 "del Monginevro", accessibility to the Olympic districts of Pragelato and Sestriere (in the Chisone Valley) and San Sicario (in the Susa Valley). From Perosa Argentina (at about 600 m.a.s.l., the highway climbs up to the Sestriere Pass (at about 2030 m.a.s.l.) along the Chisone Valley, crossing the territories of the Municipalities of Perosa Argentina, Roure, Fenestrelle, Usseaux, Pragelato and Sestriere. From Sestriere Pass the highway descends towards Cesana Torinese (at about 1350 m.a.s.l.) in the district of the Susa Valley, into the territories of the Municipalities of Sestriere and Cesana Torinese. The section of the ex S.S. 23 "del Colle del Sestriere" concerned by the planned intervention lies between the towns of Perosa Argentina and Cesana Torinese, for an area of around 50 kilometres. The planned intervention consists essentially in around 95 one-off interventions in the infrastructure - adjustment of curves, implementation of safety measures at road crossings, consolidation of road structures and, optimisation of the hydraulic regime, replacement of safety barriers, etc. - and general interventions such as tar resurfacing, replacement of road signs, optimisation of carriageway drainage - all of which are aimed at upgrading the functionality of the highway. Among the one-off interventions, particularly important are: the avalanche barrier tunnel in the Municipality of Fenestrelle, the parking area in the Municipality of Pragelato, the redesigning of several road junctions and the adjustments planned around Cesana Torinese. The avalanche barrier tunnel, as an intervention of major technical and economic importance is located in the territory of the Municipality of Fenestrelle near the boundary with the Municipality of Usseaux. This structure, located on the left orographic side of the Chisone Valley, is made up of two sections, the first 235m long and the second with a length of 125m intercalated with a section of 60m near the rocky spur on the curve. More protecting snow barriers are planned against the fall of boulders in this intermediate section and in the end section of the avalanche barriers as an addition to the safety measures already present. The main function of the construction will be to protect the roadway from avalanches that have their origin on the upper part of the slopes and against which remedies were attempted in the past by laying active snow barriers. Their effectiveness was not sufficient to eliminate the risk of a temporary blockage of the highway. The cement construction in pre-compressed reinforced concrete, open on the side facing the valley, will be built as an overhang over the carriageway creating a continuous window all along the protected section. The upper part of the construction will be filled in and planted with greenery so that it blends in with the slopes above and creates a natural slide for the masses of snow that could detach from the slope.