The TBM are large, highly automated machines that also serve to lay the precast concrete elements that cover the entire excavation profile. A layer of gravel is placed between the rock and the tubbing segments in order to ensure continuous contact between the excavation profile and the lining and to drain water from the mountain towards the floor of the tunnel.

The TBM are assembled on site prior to the commencement of the excavation work. This requires preparation spanning several months. At the end of the excavation work, the machines will be disassembled before being used again at other construction sites in Europe.

The TBM have a precision control system with laser technology, meaning that the two sides of the tunnel being excavated will meet with centimetre precision. 

A tunnelling team ensures that the excavation work continues around the clock, working in three shifts in order to keep disruptions to a minimum. The tunnelling area is supplied with electricity, water and fresh air via pipelines. Lorries are used to transport the precast concrete elements as well as other necessary materials and personnel to the TBM.