GENERAL INFORMATION ON THE CONSTRUCTION LOT

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.

Current construction work

• A reinforced concrete retaining wall along the Sill, around 200 m long and over 9 m high, with its foundation on bored pilings. This is where the railway line will run above ground between Innsbruck main station and the north portal of the BBT. Further structures linked to the retaining wall are currently being erected (cable collector and emergency reservoir). The first landfill works are taking place, too
• The portal of the "Viller Berg" tunnel, which is the north portal of the Brenner base tunnel. Here, the BBT runs southwards for 55 km completely underground to Fortezza
• The "Silltal" tunnel through the eastern slope of the Bergisel; it is approximately 130 metres long and built as a cut-and-cover reinforded concrete box, including the northern and southern portals. Since the concrete works are nearly complete, the tunnel is currently being covered over by landfill in order to recreate the original shape of the terrain
• Two railway bridges over the Sill, one for the east and one for the west track. Both bridges will be built as open steel trellis bridges; the one on the west track will also be enclosed with a reinforced concrete superstructure, in order not to cause ventilation issues in the event of a fire

Completed construction work

• Access bridge
• The two tunnel tubes, each approx. 130 m long, of the "Viller Berg" tunnel stretch into the adjacent bedrock, integrating and permanently securing the portal structure within the slope
• 350 m of river engineering works to ensure that the course of the Sill is as close to nature/ecological as possible
• The former AGA weir was removed in 2021 and replaced by a fish-passable riverbed
• Pedestrian bridge over the Sill connecting hiking trails from the urban area to the local recreation area in the Sill Gorge
• Slope stabilization work for Silltal tunnel and Viller Berg tunnel

Ecological aspects in H21

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.

GENERAL INFORMATION ON THE CONSTRUCTION LOT

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:

• Remaining excavation of the Innsbruck emergency stop including excavation by blasting of the western mail tunnel tube up to the western assembly chamber for the TBM and to the eastern assembly chamber for the TBM
• Blasting of main tunnel tubes northwards from Ahrental to the location of the breakthrough in the H21 "Sill Gorge" construction lot (east tube approx. 2,331 m long, west tube approx. 3,415 m long)
• Mechanical excavation of the main tunnel tubes southwards from Ahrental up to the border of the future construction lot H53 "Pfons-Brenner" (east tube approx. 8,108 m long, west tube approx. 8,396 m long)
• Inner lining operations in both main tunnel tubes, each approx. 14.4 km long, as well as in the Innsbruck emergency stop, the Ahrental cross-chamber, the cross passages (every 333 m), in the exploratory tunnel, in the Ahrental access tunnel including the Ahrental ventilation chamber and in the Patsch shaft as well as in the Sill Gorge access tunnel
• Partition wall for the Innsbruck connecting tunnel east and west and tracks in side corridors (safety corridor) for the Innsbruck connecting tunnel east and west
• Long-distance flushing system in the connecting tunnels Innsbruck east and west
• Construction of a 69.4 metre long bridge over the A13 Brenner motorway

The following optional work was also tendered:

• Remaining concrete inner lining in the Tulfes emergency tunnel

Current construction work:

• Erection of partition walls for the Innsbruck connecting tunnel east and west and tracks in side corridors (safety corridor)
• Installation of the long-distance flushing system in the connecting tunnels Innsbruck east and west
• Excavation main tunnel west northwards (Innsbruck)
• Excavation main tunnel east northwards (Innsbruck)
• Excavation main tunnel east southwards with TBM Lilia
• Excavation main tunnel west southwards with TBM Ida

Completed construction work:

• Construction of conveyor belt systems from underground to the Ahrental disposal site
• Blasting assembly chamber west
• Blasting assembly chamber east
• Reinforcement works in the expolatory tunnel
• Excavation emergency stop
• Building of a production hall for the manufacture of tubbing rings (pre-cast concrete elements for the inner lining)
• Construction of conveyor belt systems from underground to the Padastertal disposal site
• Bridge over the A13 Brenner motorway

GENERAL INFORMATION ON THE CONSTRUCTION LOT

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:

• Tulfes emergency tunnel
• Innsbruck emergency stop
• Main tunnel tubes
• Connecting tunnels
• Ahrental-Pfons exploratory tunnel

Construction works

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.

Main tunnel tubes

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 .

Connecting tunnel between the BBT and the Innsbruck bypass

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.

Exploratory Tunnel

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.

GENERAL INFORMATION ON THE CONSTRUCTION LOT

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:

• 0.9 km of exploratory tunnel excavated southwards
• 3.0 km of main tunnel excavated southwards
• 0.6 km of connecting tunnels
• 0.3 km of cross-passages

Completed construction work

• Excavation work in the southern exploratory tunnel and in the main tubes, starting from the auxiliary drivage
• Installation of an approx. 9 km long conveyor belt to the "H41 Sill Gorge-Pfons" construction lot
• Construction of an auxiliary drivage from the exploratory tunnel to the main tunnel tubes in the Hochstegen zone
• Excavation of the northern transition to the Hochstegen marble in the exploratory tunnel and the main tunnel tubes
• Construction of a cross-over point
• Injection measures in the area of the exploratory tunnel in the section of the Hochstegen marble

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.

GENERAL INFORMATION ON THE CONSTRUCTION LOT

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:

• ca. 15.2 km of main tunnel northwards using a TBM
• ca. 10.0 km of main tunnel southwards using the NATM method
• ca. 1.3 km of exploratory tunnel southwards
• ca. 2.6 km of cross passages (37)

The construction lot includes the following inner lining works:

• ca. 15.6 km of exploratory tunnel
• ca. 15.6 km of main east tunnel
• ca. 15.5 km of main west tunnel
• ca. 3.1 km of cross passages (45)
• ca. 5.1 km of auxiliary structures (Wolf access tunnel, spoil tunnel, etc.)