Axel’s journey to the centre of the Earth

Armed with off-road tires that would be the envy of an SUV, Axel enters the tunnel and vanishes into the dark heart of the earth. The vehicle looks like a tractor built to work the fields, but its performance is something else entirely. Axel (Autonomous Exploration Electrified Vehicle) is a tele-guided rover robot designed for tunnel inspection unique in the world. Commissioned by the Webuild Group, it was built by the Turin-based CIM4.0 (Competence Industry Manufacturing 4.0) in order to respond to a specific need: to penetrate the Piedmontese mountains and explore a 3-kilometer-long tunnel, thus avoiding any risk for human beings.

Axel’s training camp was the “Nicchie La Maddalena” construction site in Chiomonte, part of the Italian section of the Turin-Lyon line’s base tunnel connecting Italy and France, where the consortium consisting of CSC Costruzioni SA (Webuild Group) and Webuild has been operating since 2020. This is a crucial portion of this ambitious high-speed railway project that belongs to the TEN-T rail transport networks that are being financed by the European Union to link the continent from end to end.

“The Axel project was created by Webuild Group together with partner CSC, and commissioned by client TELT within the La Maddalena consortium, to offer a service capable of examining an unexplored tunnel section without the use of personnel, and therefore without any threat to safety,” said Stefano Mosconi, project manager of Webuild. “We can say that it is the first time in the world that a rover of this type and in this working environment has been deployed.”

Axel is an example of how robotics applied to the world of infrastructure not only improves innovation in data analysis, but can also increase safety for people on worksites. Axel’s task is to collect data in extreme conditions: the tunnel he is entering is 7 kilometres long, 6 metres (19 feet) wide, and has an uneven bottom and copious amounts of water. Moreover, the temperature reaches 40 degrees Celsius (104 degrees Farenheit) and the air contains a very high level of humidity.

The robot’s rugged characteristics allow it to be driven remotely from a base station up to 2 kilometres away. Axel can overcome large obstacles such as depressions and slopes of more than 60%, and can wade across water up to 30 centimetres (11 inches) deep. It is powered entirely by electricity, with zero impact on the environment.

“We are talking about a highly sustainable solution, because the rover is entirely powered by an electric engine, which has the added benefit of avoiding pollution of the data collection resulting from exhaust gases,” said Mosconi.

These features allow Axel to slip into the long tunnel at the “Nicchie la Maddalena” site, collecting the necessary data to ensure it will be safe for the men who will be work in the tunnel to enter.

The robot’s design is the result of a study conducted in partnership between Webuild and Competence Industry Manufacturing 4.0 in Turin that included the development of remote laboratories to test the machine, as well as a series of pre-tests to verify the calibration of sensors and communication.

The result is a prototype that looks like a tractor, but hides a full array of equipment like cameras, sensors, and antennas, all in a vehicle that is 3.5 metres (11.5 feet) long and weighs 2,200 kg (4,800 pounds).

“The rover communicates with us thanks to the 5 gigaherz radios, one placed on the back of the vehicle and the other near the cabin,” explains Pasquale Russo, Axel’s remote pilot. “Axel communicates with our console and transmits video and data in real time. At the same time, we communicate with him from the console, guiding him.”

Axel’s journey into the centre of the earth takes him inside the Nicchie la Maddalena site tunnel, one of the sites on the Italian side of the future Turin-Lyon highspeed rail link. The information collected by Axel will be essential to provide valuable input to proceed with the excavation on the Italian side of the cross-border TELT (Tunnel Euralpin Lyon Turin).

On the Maddalena side, the project approved in 2018, calls for the excavation of the base tunnel to be carried out from Chiomonte, and no longer from Susa as originally planned. Consequently, the Maddalena site will be used not only for the geological analysis of the rocks, but also for the construction of 22 interchange niches that will be built and inserted as recesses along the tunnel. They are needed to allow the construction vehicles to pass one another safely in the tunnels. The niches, from 30 to 65 metres (98-213 feet) long and about 4.5 metres (11.5 feet) deep, will be excavated with traditional methods in a time estimated at about 20 months.

All this is necessary to build the TELT section of the high speed/high-capacity Turin-Lyon railway. The TELT is 65 kilometres (40 miles) of railway between Susa in Piedmont and Saint-Jean-de-Maurienne in French Savoy, of which 57.5 kilometres (35.7 miles) is underground.

An important infrastructure project connecting the high-speed lines in Italy and France, supporting the development of sustainable mobility in Europe that should be completed in 2030, when the new high-speed Turin-Lyon line will cut down road traffic reducing harmful emissions by 3 million tonnes of Co2 per year.