The international section of the Lyon-Turin line spans about 70 km between Saint-Jean-de-Maurienne in Savoie and Bussoleno in Piemonte, and is the only part of the line on which work has started. The 57.5 km Mont d'Ambin base tunnel is being dug at the base of the Mont d'Ambin and is the major engineering work of the overall future Turin-Lyon line. An underground service and rescue train station is planned around the half-way point of the tunnel, East of Modane.