Brenner Base Tunnel

At 63 kilometers in length, the Brenner Base Tunnel (BBT) was constructed through the base of the Eastern Alps beneath the Brenner Pass. It is the most critical infrastructure project of the Scandinavian-Mediterranean Corridor. This corridor overcomes the Alps barrier to connect Finland and Sweden in northern Europe with the Italian ports in the south.  

The BBT runs beneath 1,700 meters of complex rock mass massifs. Its construction included excavating two 9.04-meter inner diameter single-track tunnels approximately 70 meters apart and connected by transversal galleries. The tunnel replaces part of the Brenner Railway which had a maximum speed of 70 kilometers per hour. 

On the axis of railway tunnels 11 meters underneath, an Exploratory Tunnel was bored to be used first as a final geological investigation and then as emergency access. The BBT Double Shield TBMs used several investigation techniques to provide information on ground and rock conditions several meters onwards, helping engineers to adapt the TBMs in advance for better and more efficient performance. Given the geomechanical hazards, including squeezing and face instability, precious water resources needed to be preserved. 

In addition to using our expertise to assist with TBM selection, TYLin designed the TBM launching frames and precast segmental lining (geometry, materials, and manufacturing processes). We defined the methodologies for TBM advance, interpreted data from the boreholes in advance (150 meters every 100 meters), and the geophysical test. The team provided drainage ahead of excavation and lining monitoring. Finally, we identified the stretches where consolidation is needed and designed the intervention based on the condition.