Mont d'Ambin base tunnel

The Mont d'Ambin Base Tunnel, also known as the Mont Cenis Base Tunnel, is the largest engineering work of the Lyon–Turin rail link project. Once completed, it will facilitate the principal high-speed rail link between Italy and France, conveying both high-speed passenger trains and rail freight between the two countries. At 57.5 kilometres (35.7 mi), that tunnel will be the longest rail tunnel in the world, slightly ahead of the 57.1 km (35.5 mi) Gotthard Base Tunnel in Switzerland. It represents one third of the estimated overall cost of the project and is the only part of the line where work has started. This tunnel will pass through the Alps between the Susa Valley in Piedmont and Maurienne in Savoie. It has an estimated cost of €8 billion. During September 2016, a key agreement towards the tunnel's construction was reached by France and Italy. Three years later, competitive tenders to perform packaged elements of the construction work were sought. As of July 2024, the expected completion date for the base tunnel was 2033.

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).