TELT Interchange Niches of the Maddalena

High Speed Railways

Start of works

May 2021

Progress status


Data updated to April 2022

Chiomonte, Turin, Italy

The Maddalena tunnel, located in Chiomonte (Turin), is one of the construction sites of the Italian side of the Turin-Lyon railway line. It was created as a geognostic tunnel with the aim of providing the geological information useful to proceed with the excavation of the base tunnel on the Italian side of the TELT railway line, which will connect Turin with Lyon.

The construction site variant that moved the excavation of the base tunnel from Susa to Chiomonte has been approved. The site will be used not only to conduct a geological survey of the rocks, but also for the construction of 22 niches to adapt the tunnel to the passage of construction vehicles.

The niches, given the small size of the tunnel, will be 30 to 65 meters long, about 4.50 meters deep, and will allow vehicles to cross safely. They will be excavated with traditional methods over a period of 20 months, and will be used for service access for vehicles and equipment that will operate in the construction site of the base tunnel. The intervention also includes the formation of a driveway preparatory to the execution of the work, and laying of the coating of the first phase along the entire development of the tunnel.

Commissioned by TELT (Tunnel Euralpin Lyon Turin), the project will be carried out by Webuild and CSC Costruzioni SA (Webuild Group).

The work is part of the larger TELT project, the High Speed/High Capacity line planned under the Alps to connect Turin and Lyon, an important piece of the Trans-European Transport Network (TEN-T), the European Union’s ambitious sustainable mobility initiative to connect the continent’s rail networks and increase the transport of people and goods by rail instead of road.

The T.E.L.T. project

The Tunnel Euralpin Lyon Turin (or TELT) will extend 65 kilometres between Susa in Piedmont, and Saint-Jean-de-Maurienne in Savoie, France. Of the total section, 57.5 kilometers will be excavated underground, and of these about 10 kilometres have already been constructed.

TELT is an important part of the Mediterranean Corridor of the TEN-T network that will connect southwestern Europe with the countries of Central and Eastern Europe. By 2030, the Turin-Lyon railway will make it possible to reduce road traffic by contributing to the reduction of 3,000,000 tons of CO2 each year.

The 7-kilometre exploratory tunnel is the largest Italian construction site to date for TELT. The tunnel, completed in February 2017, was excavated in order to better investigate the geological structure of the mountain through which the TELT base tunnel will pass.

Webuild is also employed on other lots throughout the TELT project. The Group and its partners are engaged in the construction of Lot 2 (awarded in July 2021, it has a value of €1.43 billion, and concerns the excavation of a 46 km section of the line tunnels and auxiliary tunnels between La Praz and Saint-Martin-de-la-Porte, in France) and Lot 5A (awarded in 2020, it involves preparatory works for the construction of a safety site at Modane and four ventilation shafts that will serve the future base tunnel and the construction of a logistics hub 500 metres below the Ambin Massif).



AXEL ( Authonomus Exploration Electrified ) is the high-performance rover for inspection of critical environments. For the first time in Italy, and on this scale, tunnelling exploration is being automated. Robotics, in fact, is often used in industry and oil & gas, but little in excavations (unless in very small sections such as hydraulic tunnels).

The rover was developed by Webuild with CIM (Competence Industry Manufacturing 4.0, one of the main Italian technological Competence Centres) in order to carry out the exploration of the last 3 km of the geognostic tunnel of La Maddalena and build in total safety the preliminary surveys of the underground environment, and then equip the tunnel with the necessary systems to allow the workers to work safely.

Axel can collect environmental parameters to identify areas where operators can safely intervene and highlight critical situations. It can monitor temperature, humidity and the presence of gases such as – among others – carbon monoxide, hydrogen sulphide and flammable gases.

With a range of 2 km for the maximum distance of remote driving, Axel is a zero-emission robot, fully electric and with batteries that give him a range of 10 km, while its wheels, with a diameter of 60 cm, allow him to overcome obstacles that are even 30 cm in height.