Tunnelling starts on French entrance portal
19 December 2022Excavation work has started on the entrance portal on the French side of the base tunnel for the Lyon-Turin railway.
The tunnel 3km tunnel connecting Saint Jean de Maurienne and Saint Julien Montdenis will be added to the 10.5km completed in April between Saint Martin la Porte and La Praz, near the border with Italy.
A consortium comprising Implenia, NGE, Itinera and Rizzani De Eccher will excavate the tunnel stretching from the French entrance portal using traditional methods (hydraulic breakers and/or explosives). More than 1km of the tunnel will be an umbrella vault.
Implenia says the preparatory work has already been demanding. It has included building 794 jet grouting columns to improve the mechanical properties of the soil in the alluvial zone, as well as a Parisian wall. For the excavation of the ‘spandrel zone’, 290,000 tons of material were excavated – a total of approximately 600,000m3 for the entire project.
The consortium is currently constructing three acoustic buildings to reduce noise and dust pollution for local residents.
The Lyon-Turin line will be 270km long and include the 57.5km Mont Cenis Base Tunnel. The tunnel, which will connect Italy’s Susa Valley with France’s St Jean-de-Maurienne, will enable passenger trains to travel at speeds up to 220km/h and freight trains at 110km/h.
The Lyon-Turin line is designed to transport 40 million tons of goods and 5 million passengers each year, shifting 1 million heavy vehicles from road to rail and reducing annual CO2 emissions by 3 million tons.
A consortium of Vinci Construction Grands Projets, Dodin Campenon Bernard, Vinci Construction France TP Lyon and Webuild has the Lot 2 contract to build the 23km tunnel between Saint-Martin-la-Porte/La Praz and Modane.
