page_title: Mont d'Ambin Base Tunnel
section_title: Characteristics
hierarchical_section_title: Mont d'Ambin Base Tunnel / Characteristics
caption_attribution_description: Italiano: Profilo geotermico del tunnel di base lungo la Nuova Linea Torino Lione English: Geothermal profile of new Turin-Lyon railway base tunnel
context_page_description: The Mont d'Ambin base tunnel is the largest engineering work of the Lyon–Turin rail link project. Reconnaissance work began on the French side in 2002 with the excavation of access points at Modane, then Saint Martin la Porte and La Praz, and on the Italian side in 2011 at La Maddalena. Construction has yet to start officially, but the 9 km reconnaissance gallery already tunneled from Saint Martin de la Porte towards Italy is bored along the axis of the South tube of the tunnel and at its final diameter. In March 2019, the Italians published calls for tender for tunneling of the French portion and in July 2019 for tunneling of their portion.
context_section_description: Following protests against the original alignment of the base tunnel in the Susa valley, its length was increased from 52 to 57.5 km (35.7 mi). When it opens, it will be the longest rail tunnel in the world, followed by the Gotthard Base Tunnel (57.1 km), the Brenner Base Tunnel (55 km, currently under construction), the Seikan Tunnel (53,85 km), the Channel Tunnel (50.45 km), and the Yulhyeon Tunnel (50.3 km).
  The portals will be in Saint-Jean-de-Maurienne on the French side and Susa on the Italian side.
  The cost of the joint Franco-Italian section (from Saint Jean de Maurienne to Val Susa) is estimated at 8 billion euros (in January 2018 value). The cost will be borne by the French and Italian governments, and from EU funds.
  The tunnel will be used by  freight trains and freight shuttles running at 100 km/h and by higher speed passenger trains operating at 220 km/h.
caption: Geothermal profile of new Turin-Lyon railway base tunnel
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