The world's longest underground railway connection

The Brenner Base Tunnel is being built from the Tulfes portal near Innsbruck to Fortezza in South Tyrol, Italy, over a total length of 64 kilometers. When completed it will be the longest underground rail link in the world. It is the centerpiece of the Scandinavian-Mediterranean Trans-European Network (TEN) from Helsinki (Finland) to Valletta (Malta).

In 2018, 2.4 million trucks crossed the Brenner Pass by road. The Brenner Base Tunnel will allow heavy traffic to be shifted from road to rail for the benefit of local residents and the environment. In future, the almost horizontal tunnel route will eliminate the uphill and downhill gradients of the existing Brenner railway alignment, which is over 140 years old and runs over the 1,371 meter high Brenner Pass.

Hard rock specialists for tunnel superlative

A special feature of the project is the exploratory tunnel driven through the rock before the two main tubes. In addition to exploring the geology, for example with regard to the expected fault zones, later, when the trains are running, the gallery (centered 12 meters below the two main tubes) will take on the function of a drainage and maintenance tunnel.

For the exploratory tunnel on the Austrian side, Herrenknecht supplied an approximately 200 meter long and 1,800 tonne Gripper TBM with a diameter of 7.9 meters. After assembly in a cavern 3.5 kilometers deep inside the mountain, in September 2015 it began its 16.7 kilometer drive from Ahrental in Austria toward the Italian border.

Five disc cutters of the Gripper TBM’s cutterhead were equipped with the DCRM (Disc Cutter Rotation Monitoring) system, which monitors the rotational movement and temperature of the disc cutters, allowing optimization of the tool maintenance intervals. Additionally, a camera system provided photos of the tunnel face to the control cabin monitors.

First milestone mastered

On Monday, July 6, 2020, with the breakthrough of the exploratory tunnel, proud tunnelers at the Brenner Base Tunnel celebrated the first decisive milestone. The Gripper TBM for the northern section of the exploratory tunnel broke through the rock to the target cavern after previous top performances of up to over 61 meters per day.

Project Facts

  • Longest underground rail link in the world
  • Eight Herrenknecht TBMs for a total of approc. 90 km of tunnel
  • Up to over 61 m of tunnelling per day
  • Up to 860 m of tunnelling per month
  • Additional equipment and services provided by Group companies

Up to 860 meters of tunnel bored and lined per month

Herrenknecht supplied for the tunnelling lots south of the Brenner Pass three machines: two large-diameter Double Shield TBMs (Ø 10,650mm) are being used for the 14 kilometer southern drive of the two main tubes from Italy. A smaller diameter Double Shield TBM (Ø 6,800mm) has been boring the southern section of the exploratory and later drainage and service tunnel.

The smaller Double Shield "Serena" began its drive in May 2018 and by the turn of the year 2021 / 2022 the machines reached the end of its tunnelling mission after 14.1 kilometers. The two large-diameter TBMs "Flavia" and "Virginia" began tunnelling through the Brenner in early summer 2019. With "Virginia" the miners set a new record in mechanized tunnelling: in March, miners and project owner proudly announced an advance rate of 860 meters in a month.

Northern main tubes

For the excavation of the two northern main tubes, Herrenknecht records the orders for two Single Shield TBMs (Ø 10,250mm) as well as for two Double Shield TBMs (Ø 10,330mm).

Muck removal

A highlight of the Brenner Base Tunnel megaproject is a huge belt conveyor system Herrenknecht, in cooperation with its subsidiary H+E Logistik GmbH in Bochum, developed and built at the Wolf access tunnel. The conveyor system has a nominal capacity of up to 5,000 tonnes of rock per hour. If there wasn't such a central belt conveyor system, 190 trucks with a load capacity of 26 tonnes each would have to drive in and out of the tunnel every hour to handle the removal and relocation of the excavated material. The entire conveyor system is controlled and monitored from a central control center.


In addition to the eight tunnel boring machines and the belt conveyor system at the Wolf access tunnel, other deliverables from the Herrenknecht Group support the Brenner jobsites: TUnIS TBM navigation system with apps for mobile system access, e.g. for surveyors, from VMT; invert segment formwork from Herrenknecht Formwork; tunnelling professionals from Global Tunnelling Experts; formwork for segment production and the lining of conventionally excavated tunnel sections as well as handling equipment from Euroform.

Brenner Base Tunnel

Project Data
Column 0 Column 1
Tunnelling Length approx. 90 km
Rock: Quartz, slate
Client Brenner Basistunnel BBT SE
ARGE H33 Tulfes-Pfons (STRABAG AG, Webuild)
ARGE H61 Mauls 2–3, BTC S.c.a.r.l. (Astaldi S.p.A., Ghella  S.p.A., P.A.C. S.p.A., Cogeis S.p.A.)
ARGE H41 Sillschlucht-Pfons ( Implenia Österreich GmbH, Implenia Schweiz AG, Webuild S.p.A, CSC costruzioni SA)
Machine Data
1x Gripper TBM
Diameter: 7,910 mm
Lining method: Rock support
Cutterhead power: 3,500 kW

1x Double Shield TBM
Diameter: 6,800 mm
Lining method: Segmental lining
Cutterhead power: 2,800 kW

2x Double Shield TBM
Diameter: 10,650 mm
Lining method: Segmental lining
Cutterhead power: 4,200 kW

2x Single Shield TBM
Diameter: 10,250 mm
Lining method: Segmental lining

2x Double Shield TBM
Diameter: 10,330 mm
Lining method: Segmental lining

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Steffen Dubé President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.

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Steffen Dubé President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.