Brenner Base Tunnel

The Brenner Base Tunnel (BBT) connects Austria and Italy. The rail tunnel forms the heart of the Scandinavian-Mediterranean TEN corridors from Helsinki to Valetta and runs for 55 km from Innsbruck to Franzensfeste.
 
Taking into account the existing Innsbruck bypass tunnel, this results in the longest underground rail tunnel in the world with a total length of 64 km.
 
The BBT consists of two single-track tubes, each 8.1 m wide and 70 m apart. The two tubes are connected every 333 m by connecting side tunnels, which serve as escape routes in emergencies. There are also three emergency call stations.
 
A special feature of the Brenner Base Tunnel is the continuous exploratory tunnel beneath the two single-track tubes. It is located in the middle at a depth of around 12 m and has a diameter of 5 to 8 m. In total, the tunnel system of the Brenner Base Tunnel comprises approx. 230 tunnel kilometres.
 
The almost horizontal tunnel route avoids the gradients of the existing Brenner line, which is more than 140 years old. The total cost of the project, which is scheduled for completion in 2032, is estimated at €10.535 billion.
 
STRABAG has been involved in the Austrian section of the BBT since 2009, contributing its expertise as a technical leader and problem solver under geologically challenging conditions in various construction lots (EBN, AFA, KSP and ATP). At the heart of the BBT are the approximately 7 km long intersecting connecting tunnels that link the east-west route of the Inntal Tunnel, completed in 1994, with the north-south tubes of the BBT. This connection could only be achieved through the integration of the EBN, AFA and ATP construction lots by STRABAG. With the breakthrough in the exploratory tunnel in July 2020, Innsbruck was connected to lot H51 and, with the geologically challenging “Iris” auxiliary drive, another essential foundation was laid for the main tube drives in lots H41/H53 in the summer of 2021.