The TBM Gaia is currently at work on the main tunnel of the Collettore Mediano in Turin, a strategic infrastructure for the city. The machine is excavating a 9.5 km tunnel, crossing heterogeneous soils more than 10 meters below the groundwater level using the Hydroshield technique, an advanced solution that applies constant counterpressure to stabilize hydraulic pressure and the excavation face, while minimizing surface deformations. 

The excavated material is mixed with bentonite slurry and pumped out through dedicated pipelines, then separated at the core of the system’s operations: the Soil Treatment Plant (STP), installed in a logistics area near the TBM’s launch shaft. 

The TBM is designed to install a segmental lining made up of 6+0 reinforced concrete segments, with an internal diameter of 3,200 mm and a thickness of 300 mm. The cutting head is equipped with 18 disc cutters, which can be replaced by rippers depending on ground conditions. 

The excavation diameter is 4,080 mm and the maximum thrust during advancement can exceed 1,200 tons. The system can achieve a daily progress of more than 20 meters of excavation and lining installation, equivalent to over 300 m³ of material moved per day.

In total, more than 124,000 m³ of material will be excavated and sent to recovery plants. The final lining of the tunnel will consist of 7,758 prefabricated reinforced concrete rings. 

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