Mont Cenis Base Tunnel: Optimized Tunnel Lining for Gripper TBM Tunnelling

Credit/Quelle: TELT

1 Overview of the cross-border section of the Lyon–Turin tunnel under Mont Cenis, with Lot CO5 of the two Gripper TBMs with the Wurm visible in the center

Credit/Quelle: TELT

2 The first of six Herrenknecht TBMs, the 180 m long “Viviana” with a diameter of 10.34 m, will drive the approximately 9 km long tunnel between Saint-Martin-La-Porte and La Praz

Credit/Quelle: TELT

Credit/Quelle: Herrenknecht AG

3+4 Two Herrenknecht Gripper TBMs (Ø 10.43 m) for Lot CO5 of the Mont Cenis Base Tunnel

Credit/Quelle: Herrenknecht AG

5 The Wurm lining and installation system for the southern lots of the Gotthard Base Tunnel

Credit/Quelle: Herrenknecht AG

6 Schematic overview of operation of the Wurm for Lot CO5 of the Mont Cenis Base Tunnel: Cross-section before the Wurm, concreting work on the Wurm, cross-section after the Wurm (from left to right)

Credit/Quelle: Herrenknecht AG

The two parallel 57.5 km long tunnels under Mont Cenis are the key structures of the new railway link currently under construction in the Alpine areas between Lyon in France and Turin in Italy. When the Mont Cenis Base Tunnel opens in 2033, it will be the longest railway tunnel in the world. For the excavation, the contracting joint ventures have ordered six Herrenknecht tunnel boring machines to date, including two 334 m long Gripper TBMs and two 650 m long lining and installation systems – known as “Wurm”. Their job is to help the miners complete the lining of the bored tunnels within the specified time frame.

1 Project Overview

The new 164 km railway link between Lyon and Turin closes a gap in European infrastructure in terms of the rail network. It will form part of the Mediterranean corridor within the EU‘s Trans-European Transport Network (TEN-T). The centerpiece of the new line will be the 57.5 km long base tunnel under Mont Cenis, with the French-Italian TELT (Tunnel Euralpin Lyon Turin) responsible for the project. As of May 2025, 17.2 km of what will be the world‘s longest railway tunnel had been excavated. It is a complex system consisting of two parallel main tubes, four access tunnels and...