Mechanised digging using a TBM

TBMs – Tunnel Boring Machines are impressive machines, custom-built to dig underground quickly and safely. The cutter is configured as a “travelling industry”: it allows to mechanise and automate all the excavation, clearing, and soil transport activities, thus reducing to a minimum both the work time and the number of operators that have to be present. The cutters on the cutter head break the rock without abrading it, thus limiting the formation of dust and therefore its dispersion in the environment.

Traditional excavation using explosives

This is used in the more complex mountain sections. This technique involves making holes in the rock wall which are then filled with explosives and subsequently ignited. After the debris are removed, the front is consolidated with beams and sprayed concrete. In some cases, the shell can be reinforced with steel bars.

Traditional excavation using pneumatic drills

Where the rock is less resistant and explosives cannot be used, progress is made using pneumatic drills, with the excavation again being consolidated with beams and concrete.