Brenner Base Tunnel: TBM Wilma completes first continuous main tunnel tube

Thousands of cutterhead rotations, nearly 7.5 kilometres of tunnelling, more than 23,000 tubbing rings installed, and the passage through challenging geological fault zones are now behind it. On August 25th, the tunnel boring machine Wilma reached its final destination. 
With this first successful breakthrough in a main rail tunnel, the entire 55-kilometre length of the western main tunnel tube of the Brenner Base Tunnel is now complete.  From the Sill Gorge near Innsbruck to Fortezza in Alto Adige, numerous individual tunnel sections have now been joined to form one continuous main tunnel.

706 days in operation – a success made possible by the people behind the machine
The decisive moment was, understandably, an emotional one: As the 260-tonne cutterhead broke through the final centimetres of rock, the sense of relief, joy and pride among the staff of the project company BBT SE and the H53 Brenner Base Tunnel joint venture responsible for the construction was clearly palpable.

The road to today’s breakthrough was anything but straightforward. On several occasions, the tunnel boring machine encountered geological fault zones, where the characteristics of the rock changed significantly within just a few metres. 

TBM Wilma – a factory deep inside the mountain

On September 18th, 2024, Wilma was officially launched in the H53 Pfons–Brenner construction lot. From there, the tunnel boring machine worked its way through the mountains towards Innsbruck.
With a total length of around 180 metres, a boring diameter of 10.37 metres and a total weight of around 2,700 tonnes, Wilma is a highly complex underground production facility. 

As the cutterhead worked its way through the rock at the front, numerous processes were taking place simultaneously inside the machine: Tubbing rings were delivered by construction site trains and installed automatically; the excavated material was removed via conveyor belt systems, technical systems were maintained on an ongoing basis, and the geological conditions were closely monitored. And so, deep inside the mountain, a virtually self-sufficient construction site came into being. 

H53 Pfons-Brenner construction lot – Short-distance logistics

The scale of the project was already evident when the machine was delivered: around 80,000 individual components had to be transported to the construction site in a total of 170 specialised shipments and assembled underground in a specially constructed assembly chamber.
Logistics during tunnelling were also designed to be as efficient and environmentally friendly as possible. “In a project of this scale, logistics are at least as important as the machine itself.  We wanted to keep road transport to an absolute minimum. This allowed us to make the processes more efficient while also eliminating around 45,000 lorry journeys,” explains Michael Knapp, BBT Project Manager for the H53 Pfons–Brenner construction lot.

A key element of the logistics plan was the delivery of the tubbing segments by rail. The tubbing segments, each weighing around ten tonnes, were transported by rail to the construction site via the Wolf rail link and then made ready for installation in the tunnel boring machine.
The excavated material generated during tunnelling also only had to be transported a short distance. The excavated rock was transported via several kilometres of conveyor belts directly from the tunnel construction site to the nearby Padastertal disposal site.

Key data on TBM Wilma
•    Completion of the western main tunnel tube of the Brenner Base Tunnel
•    Breakthrough by tunnel boring machine Wilma: August 25th, 2026
•    TBM launch: September 18th, 2024
•    Length excavated: approximately 7,500 metres
•    Breakthrough: IRIS auxiliary drivage (H53 Pfons–Brenner construction lot / H41 Sill Gorge–Pfons construction lot)
•    Operating period: approximately 706 days
•    Boring diameter: 10.37 metres
•    Total length (including backup system): 180 metres
•    Total weight: 2,700 tons
•    Weight of the cutting head: 260 tons
•    Installed power performance: 9,928 kW
•    Cutterhead driving power: 4,550 kW
•    Operating torque: 22,448 kNm
•    Maximum special thrust force: 180,000kN
•    Tubbing rings: 3,720
•    Installed tubbing segments 22,320
•    Special transports for delivery: 170
•    Individual machine components: approximately 80,000