Ceresole Tunnel is the steepest tunnel in the Italian Alps

Located in the Metropolitan City of Turin in the Italian region Piedmont, Ceresole Tunnel is said to be the steepest tunnel in the Alps, with gradients of around 14-16%.

Ceresole Tunnel

Set high in the Eastern group of the Graian Alps, in the heart of the Parco Nazionale Gran Paradiso (the oldest in Italy), the tunnel is 3.535m (2.17 miles) long on the way to Colle del Nivolet.
The tunnel is totally paved and carries traffic on the Strada Provinciale 460 di Ceresole (SS460). The tunnel is lit and wide and was built in 1992. It’s said to be the steepest tunnel in the Alps with gradients of around 14-16% here and there. It starts on the eastern side at 1172m above the sea level, and ends on the western side at 1456m asl. The elevation gain is 284 meters and the average gradient is 8.03%.

To avoid the tunnel, there’s a small old service road on the left. It was properly repaved for bicycle transit due the passage of the Giro d'Italia in 2019 and features 3 hairpin turns. The bypass road allows you to admire the beauties of nature, including overhangs, waterfalls and the course of the Orco stream. The slope, in this section, is between 10% and 15%.