Construction works for the variant of State Road No. 20 (SS 20) on the section between km 138+000 and km 143+300.

Project objective

The SS 20 variant was planned to replace a highly hazardous road section affected by frequent rockfalls from the hillside; at the same time, the new alignment provides improved travel times.
State Road No. 20, which partly runs through French territory, is a major corridor as it enables access from western Liguria and France to the Piedmont Region. The Alpine chain is crossed via the Tenda Pass tunnel (between Italy and France).

Alignment description

The variant section under design has an overall length of approximately 3,800 m; travelling downhill, it diverges from the existing alignment near the built-up area of Airole.
The first structure is the Airole viaduct (L = 85 m); the alignment then continues through the “Cima di Rovere” tunnel with a total length of 1344.60 m.
Immediately downstream of this tunnel, a rockfall protection gallery (L = 120 m) was built to protect the roadway platform from potential rockfall, considering the steepness of the overhanging slope.
The alignment then continues for 96.9 m in a natural tunnel (“Lamberta”) and subsequently through an additional cut-and-cover rockfall protection gallery (L = 182 m).
The alignment then comprises, in sequence, the “Noceire” natural tunnel (L = 593.40 m) and the “Colombo” viaduct (L = 92.00 m), required to overpass the existing roadway and the Roya stream.
The variant alignment finally continues downstream with the “Bocche” natural tunnel (L = 603.60 m), at the exit of which it reconnects to the existing road network.