The rock is being excavated using mechanical tunnel boring machines, also referred to as TBM for short. So-called single-shield TBM are being deployed for this project. These comprise a drill head and shield skin, which houses and protects the propulsion system. A temporary lining made of precast concrete elements (tubbing segments) is installed at the end of the shield. The TBM advance by means of propulsion cylinders, which are in direct contact with the already laid tunnel ring.

Two TBM are drilling through the mountain from the north and south and are scheduled to meet in the middle in summer 2027. The rock is excavated with the help of around 80 cutting rollers mounted on the drilling head and is then placed on a conveyor belt that transports it out of the tunnel. The drilling head has a diameter of 12.26 metres and rotates between four and five times per minute. The machines are operated electronically with an output of approximately 2 MW, allowing for the tunnel excavation to advance by 15 to 20 metres per day over a period of two years.

The tunnel crosses several short fault zones that are unsuitable for the TBM technology. Access to these zones is gained via separate access tunnels, from which the main tunnel is excavated using conventional tunnelling methods