Four construction sites are currently in operation, three in Austria and one in Italy. If you simply click on a construction lot, it will take you directly to its brief description, the overview plan and the photo gallery.
The excavation progress of the individual tunnel structures in the various construction lots is updated regularly. Work progress is shown on a graph.
The ongoing works on the construction lot "H21 Sill Gorge" - which began in August 2020 and are scheduled to run to the end of 2024 - will provide the link between the Brenner Base Tunnel and the central station in Innsbruck. This construction lot includes the construction of an approximately 600-metre section of the line and several other structures and river engineering works. The estimated construction costs for this stretch are 59.5 million Euro and Porr Bau GmbH Kematen will carry out the works.
Compared to other construction sites in Austria, where works take place mostly underground, works at this site are largely performed above ground.
The "Sill Gorge" section mainly includes the following construction works: a supporting wall (200 metres long), a cut-and-cover tunnel (Tunnel Silltal) (130 metres long), two railway bridges over the Sill, the northern portal to the Brenner Base Tunnel and a subsequent 120-130-metre long stretch of tunnel Viller Berg Tunnel). In spite of the relatively short stretch, this construction lot comprises very complex construction activities.
The stretch leads through the narrow and thus logistically challenging Sill Gorge. The area is characterized by numerous pieces of infrastructure in the immediate vicinity such as the A12 Inntal highway, the A13 Brenner highway, the "Tirol Panorama" museum, the "Untere Sill" power plant belonging to the municipal utilities company "Innsbrucker Kommunalbetriebe", as well as the existing ÖBB railway line with the Berg Isel tunnel.
The gorge - which is mostly in its natural state - is an important recreational area for the people of Innsbruck and can be reached via several hiking trails. In order to maintain access to the Sill Gorge during the construction period, an alternative hiking trail was specially built. In addition, for easier orientation, a system showing the various trails was installed and interesting spots near the construction site marked with information boards.
At the construction site itself, the construction of the 42-metre road access bridge over the Sill has already been completed. The demolition of the old access bridge and all the river engineering works have been completed. The symbolic excavation of the western main tube southwards began at the end of October 2021. Shortly afterwards, blasting began at the future north portal of the Brenner Base Tunnel. Since May 2022, excavation has been ongoing on the two approximately 130 m long main tunnel sections of the Viller Berg into the adjacent bedrock, where the breakthrough of the "Sillschlucht-Pfons" construction lot H41 from the north is expected in 2024. At the present time (June 2023), the retaining wall is visibly taking shape on the orographic left side of the river. The future tracks that will connect the Silltal tunnel with the Innsbruck railway station will run on this wall.
Work is also currently underway on two railway bridges over the Sill, the supporting structure for which has already been built. Furthermore, a 55 m long span bridge for pedestrians was built over the Sill, which will be part of the hiking tail network in the Sill Gorge in the future.
Completed construction work
An important part of the construction lot is the restoration of upstream fish passage in the Sill. The AGA weir, located at the entrance to the Sill gorge with a drop height of approx. 8 metres, was therefore removed and replaced by a roughly 350-m long fish ladder with a low-lying meandering channel in which water runs even during the dry season. In the course of these river engineering works, the riverbed was moved about 8 metres to the east in order to gain sufficient space on the western side for the retaining wall with the new double-track line running on it. Flood-proof and long-lasting stable embankments were constructed and re-naturalised.
Appropriate renaturalisation and restoration of the original landscape will take place, for example by backfilling the Silltal tunnel at the end of construction, including planting with typical native trees and shrubs, thus restoring the original natural condition of the area.
Main tunnel East (completed) | ||
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Excavation 120 m | Length 120 m | Cross-section 100 m² |
Main tunnel West (completed) | ||
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Excavation 130 m | Length 130 m | Cross-section 100 m² |
Works on this construction lot began in mid-January 2022 with the set-up of the construction site. Excavation works started in July 2022 towards Innsbruck with the lowering of the cross-chamber slab.
The H41 "Sill Gorge-Pfons" construction lot is located in the northern area of the BBT between the Sill Gorge of Innsbruck in the north and Pfons in the south. The Ahrental access tunnel, which has already been completed in the E41 "Ahrental" prospection lot, is used for the main excavation.
This construction lot represents the continuation of the construction works carried out in the H33 "Tulfes-Pfons" preliminary lot. The tender for the H41 construction lot was awarded on 17/11/2021 to the bidding consortium H41 Sill Gorge-Pfons comprising the companies Implenia Österreich GmbH, Implenia Schweiz AG, Webuild S.p.A, csc costruzioni sa. The total bid amount offered by the bidding consortium is 651 million euro.
In total, approx. 22.5 km of main tunnel tubes and 38 cross passages with a total length of approx. 2.3 km will be excavated by the summer of 2028 in this construction lot. In order to ensure the fastest progress possible in the whole project, the "Sill Gorge-Pfons" project area was extended southwards by three kilometres of main tunnel tubes, where it will connect to the future construction lot H53 "Pfons-Brenner".
The works basically include the following:
The following optional work was also tendered:
Current construction work:
Completed construction work:
At Herrenknecht AG in Schwanau, Germany, the first of the two tunnel boring machines (TBM) for the H41 "Sill Gorge-Pfons" construction lot of the Brenner Base Tunnel has formally passed its acceptance test. The single-shield TBM with a drilling head diameter of 10.37 metres, a length of around 160 metres and a weight of 2,420 tonnes (including its backup system) will be named "Lilia".
Today, the first parts of the TBM called "Lilia" were delivered to the H41 construction site for the Sill Gorge-Pfons construction lot, located south of Innsbruck. These are primarily single parts of the cutter head of the Tunnel Boring Machine. When assembled, this cutter head will measure about 10 meters in diameter.
The assembly of the cutter head has recently started in the Ahrental assembly chamber. The head made up of a total of five parts: the four segments and the drill head centre. Together, these parts weigh 260 tonnes. Lilia's cutter head has a diameter of 10.37 metres and is equipped with 58 cutters. Once the assembly phase is complete, the so-called "factory in the mountain" will excavate around 8.1 kilometres of the eastern main tube southwards, starting from the Ahrental assembly chamber.
The official inspection of the second tunnel boring machine (TBM) for the H41 "Sill Gorge-Pfons" construction lot of the Brenner Base Tunnel took place at Herrenknecht AG in Schwanau (D). The single-shield TBM with a drilling head diameter of also 10.37 metres, a length of around 160 metres and a weight of 2,420 tonnes (including its backup system) will be named "Ida".
The cutting head of TBM Lilia has been set up this morning in the assembly chamber. It has a diameter of 10,37 meters and weighs 263 tons.
The cutting head of TBM Ida has been set up today in the assembly chamber. It has a diameter of 10,37 meters and weighs 263 tons.
Main tunnel tubes SOUTH: TBM excavation | ||
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Excavation 2,101 m | Length 16,594 m | Cross-section 85 m² |
Mail tunnel tubes SOUTH and assembly rooms TBM: drill and blast (completed) | ||
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Excavation 258 m | Length 258 m | Cross-section 82-210 m² |
Mail tunnel tubes NORTH: drill and blast | ||
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Excavation 2,046 m | Length 5,746 m | Cross-section 70 m² |
Crosscuts | ||
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Excavation 704 m | Length 2,260 m | Cross-section 30-70 m² |
Emergency stop Innsbruck, remaining excavation (completed) | ||
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Excavation 702 m | Length 702 m | Cross-section 15-100 m² |
Since the end of September 2021, all work in this construction lot has been completed.
This construction lot was awarded to the Strabag SE / Webuild S.p.A. (ex Salini-Impregilo) bidding consortium in Summer of 2014.
construction time: 2014 - 2021
section of the tunnel to be driven: 43.3 km
awarded for: € 377 million
It consists of several structures:
Emergency tunnel
The emergency tunnel was being driven parallel to the existing Innsbruck railway bypass. It is 9.7 km long and the excavation cross-section is 35 m². The drill-and-blast excavation work on this tunnel started from three points at the same time: from Tulfes westwards, from the Ampass access tunnel eastwards and again westwards. The emergency tunnel was completed in Summer of 2017.
The main tubes have been excavated by blasting according to the so-called New Austrian Tunnel Construction Method. The ceremonial first volley was set off on 19/03/2015 in the presence of EU Commissar Violeta Bulc and the Ministers of Transportation of the 7 Alpine countries (Austria, Italy, Germany, Switzerland, France, Liechtenstein and Slovenia. This stretch includes about 6 km of main tunnels with an excavated cross-section of about 70 m2 .
Construction has been under way since summer of 2015 on the two connecting tunnels between the Brenner Base Tunnel and the existing Innsbruck bypass. The connecting tunnels were also excavated by blasting, with a cross-section of about 115 m². Excavation work was completed in Spring of 2017.
The construction lot Tulfes-Pfons included the construction of the stretch of exploratory tunnel between the Ahrental junction point and the town of Steinach am Brenner. The gripper TBM, 200 m long, started work on September 26th, 2015 and excavated about 16.7 km southwards, completing its work on July 6th, 2019. Since the breakthrough, the construction lot has been connected to the Pfons-Brenner lot.
Restoration of the collapse "Iris"
This collapse is a cavity that formed in a fault zone during the excavation of the exploratory tunnel. This had to be backfilled by means of cement mortar injections from an injection tunnel in order to rule out any effects on the overall tunnel system. As part of these repair works, the main tunnel tubes in the fault zone were excavated from July 2020 to May 2021 in advance by blasting using an auxiliary drivage from the exploratory tunnel. This allows to reduce interferences when the next TBM arrives.
Works on this construction lot began in February 2022 with the set-up of the construction site area at Wolf. On 4 May 2022, the ground-breaking ceremony took place in the costruction lot.
The H52 - Hochstegen construction lot, located within the area of the Steinach am Brenner township, is a part of the previous lot H51 - Pfons-Brenner which has now been restructured. This stretch of the project was divided in several construction lots, in order to guarantee the fastest and most efficient continuation of the works with an aim to driving the entire project forward quickly. The Wolf lateral access tunnel is used as a main access and supply route.
The Hochstegen lot is located in a zone characterized by extremely complex geological conditions. The stretch is about 500 m long, with mainly water-bearing, carbonatic rock layers, meaning that the tunnel excavation in this stretch is particularly challenging. The contract for the works in the H52 - Hochstegen construction lot was awarded to Swietelsky Tunnelbau GmbH & Co KG on December 15th, 2021. The bid was around 102 million Euro and construction time is expected to be 23 months.
The core of the project is the excavation of the exploratory tunnel southwards through the geologically challenging stretch known as "Hochstegen", where excavation will take place with the protection of preliminary sealing and stabilisation injections.
The works basically include:
Completed construction work
Hydrogeological construction support and monitoring of water resources:
With rock mass improvement measures in the form of injections, both water inflows and a lowering of the water levels in the protected areas "Hinteres Venntal" and "Hinteres Valsertal-Natura 2000" are to be avoided and the inflow quantities significantly reduced.
Main tunnel tubes | ||
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Excavation 2,977 m | Length 3,200 m | Cross-section 60-80 m² |
Exploratory tunnel | ||
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Excavation 861 m | Length 1,200 m | Cross-section 60 m² |
Cross-over and connecting side tunnels (completed) | ||
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Excavation 970 m | Length 970 m | Cross-section 25-30 m² |
On April 4, 2023, the contract for the construction lot "H53 Pfons-Brenner" was awarded to a bidder consortium consisting of Porr Bau GmbH, Marti GmbH Austria and Marti Tunnel AG Switzerland.
With this award, the tunnelling works of the last remaining construction lot of the Brenner Base Tunnel have been commissioned. The contract value for what is now the largest construction lot on Austrian project territory amounts to EUR 959 million. The scheduled construction time for this tunnel section is 70.5 months.
Construction work for this lot started on May 4, 2023, and the order was made for the two tunnel boring machines (TBM) for this lot. The two TBMs will drive a stretch of 7.6 km (a total of approx. 15.2 km) in each main tunnel tube. Due to the ordering, delivery and installation times in the contract, the tunnel boring machines are expected to start driving northwards in the fall of 2024.
Tunnelling work according to the "NATM" (New Austrian Tunnelling Method, cyclical driving) will start much earlier, moving southwards to the national border at Brenner. These works are expected to start in spring of 2024. Until then, the construction site set-up will be ongoing.
The miners will excavate around 5 km per main tunnel tube (10 km in total) in the southern section of construction lot H53 Pfons-Brenner. At the same time, excavation work will continue in the exploratory tunnel, where the miners have to drive approx. 1.3 km.
Parallel to the respective drives in the north and south of the construction lot, 37 cross-passages of approx. 70 m each, i.e. 2,590 m, are being excavated. After completing the tunnelling work in the respective sections, the inner lining work will be carried out in the entire area from the lot boundary with lot H41 Sill Gorge-Pfons to the state border at Brenner, as well as in the access tunnel in Wolf.
The construction lot includes the following excavation works:
The construction lot includes the following inner lining works:
The construction lot "Periadriatic seam", carried out between October 2011 and the summer of 2015, comprised the excavation of 3.7 km of the main tubes and 1.5 km of the exploratory tunnel. The crossing of the Periadriatic fault line, one of the biggest geological fault lines in the Alps, was accomplished without a hitch.
In May 2016 the biggest construction lot of the Brenner Base Tunnel project, known as "Mules 2-3", with a contract volume of 993 mln euro, was awarded to the bidding consortium Webuild S.p.A., Ghella S.p.A., Oberosler Cav Pietro S.r.l. (until June 2018), Cogeis S.p.A. and PAC S.p.A. Works started in September 2016.
This lot reaches from the construction lot "Isarco river underpass" up to the State border with Austria. In the course of a 7-year construction period, 39,8 km of the main tubes and 14.8 km of the exploratory tunnel will be excavated, including the emergency stop in Trens and its access tunnel as well as the bypasses which connect the main tubes every 333 m. A total of approximately 65 kilometers of tunnels will be excavated.
Once this construction lot is finished, all excavation activities in the Italian project area will be complete.
On 24/11/2021, the tunnel boring machine in the exploratory tunnel successfully reached its destination at the state border, after 14 kilometres and 3.5 years of excavation northwards. For the first time, the excavation for the tunnel tubes in the BBT project reached the Brenner Pass, which represents a historic milestone.
With the breakthrough on 19/05/2022 the "H61 Mules 2-3" and "H71 Isarco River Underpass" construction lots, which began separately, are now connected.
On March 30th, 2023, after four years, the tunnel boring machine "Virginia", working on the main east tunnel northwards, successfully reached its goal. Upon reaching the construction lot border at the Brenner Pass, with "Virginia" the first tunnel boring machine successfully ended its drillings.
Trens emergency stop
Excavation work for the connection of the Mules access tunnel with the future Trens emergency stop began in January 2017 and was completed in June 2020.
The tunnel, with an excavation cross-section of approximately 80 m2, extends over a total length of 3.8 km.
The final lining of the Trens central tunnel, of the connection and ventilation tunnels along the emergency stop is currently under construction.
Main tunnels
On 13 March 2017, excavation work began on the main tunnels moving northwards, towards the state border. After approximately 0.8 km, excavation using drilling and blasting was completed and two double-shielded TBM started excavating.
The TBM named “Flavia” is currently excavating the western main tunnel and is about 3,4 km from the State border.
The ‘Virginia’ TBM completed excavation of the east main tunnel on 30 March 2023, reaching the Brenner Pass.
The southward excavation using drilling and blasting began in April 2017 and was completed for both main tunnels in October 2020.
Final lining is currently being installed in the Access Tunnel and the Trens Emergency Stop (Trens central tunnel and connecting/ventilation tunnels). In addition, the base slabs are being laid in the section of the exploratory tunnel excavated using drilling and blasting.
Access tunnel to the emergency stop (completed) | ||
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Excavation 3,805 m | Length 3,805 m | Cross-section 80 m² |
Main tunnels | ||
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Excavation 36,479 m | Length 39,856 m | Cross-section 85 m² |
Exploratory tunnel (completed) | ||
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Excavation 14,757 m | Length 14,757 m | Cross-section 35 m² |
Crosscuts, safety- and logistics tunnels | ||
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Excavation 4,214 m | Length 6,930 m | Cross-section 26-56 m² |
The southernmost construction lot of the Brenner Base Tunnel, worth 301 million Euro, was awarded to the bidding consortium Isarco s.c.a.r.l. composed of Webuild Italia S.p.A. (formerlySalini-Impregilo), Strabag AG, Strabag S.p.A., Consorzio Integra and Collini Lavori S.p.A. bidding consortium in October of 2014. This lot links the Brenner Base Tunnel with the existing Brenner line and the railway station in Fortezza.
Since in this section the tunnel tubes are just a few meters below the surface, a portion of the activities pertaining to this construction lot is be carried out building artificial tunnels. Furthermore, as loose fluvioglacial materials and the groundwater layer will be crossed, it is be necessary to adopt specific ground consolidation procedures including ground freezing and the so-called jet grouting.
By the end of 2016, as part of the so-called preparatory works, the SS12 state road was rerouted, bridges over the Isarco river and over the Rio Bianco were built, and an underpass of the Brenner railway line was completed, as well as a direct link with the motorway. These works have therefore created enough space on the valley floor to set up the construction site and carry out the construction work. In addition, the direct link to the motorway avoids the transit of vehicles through towns in the area.
With the breakthrough at the boundary with the adjacent lot on 19 May 2022, the excavation of the main tunnels in the Isarco river underpass construction lot was completed. The H61 Mules lot and the H71 Isarco river underpass, once separate construction lots, are now joined, effectively creating a single link from Fortezza almost all the way to the Brenner Pass.
On 8 August, construction work on the future line tunnels in the 'H71 Isarco Underpass' lot at Fortezza was completed. In eight years of work, more than 6 km of tunnels and their interior lining were constructed. In the final phase of the work, the construction site will be “demobilised” and the areas will be greened, in accordance with the seasonality of the tree species.
Main tunnels (completed) | ||
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Excavation 4,478 m | Length 4,478 m | Cross-section 60-150 m² |
Connecting tunnels (completed) | ||
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Excavation 1,569 m | Length 1,569 m | Cross-section 60-80 m² |
Connecting side tunnels, Crosscuts (completed) | ||
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Excavation 170 m | Length 170 m | Cross-section 35-45 m² |
Shafts and access tunnel (completed) | ||
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Excavation 164 m | Length 164 m | Cross-section 65 m² |