ROCK TUNNELS | PROJECT
H41 - SILL GORGE TO PFONS
The H41 Lot was the first, and most northerly, package of extensive tunnelling works on the Brenner Base Tunnel itself. While H33 Lot was mostly offline for the Connecting Tunnel and tied-in to and started to open up the Ahrental area, and the H21 Lot prepared the north tip of the Brenner Base Tunnel, the works then for H41 were mostly major excavations that linked back to H21 while completing the Ahrental tunnels (including the Innsbruck Emergency Stop) and then advanced southwards with the main tubes. The tunnelling package was executed by a JV of
Implenia, Webuild and CSC Costruzioni. Contract award was in late 2021 and ground-breaking took place in mid-2022. Excavations in Lot H41 involved both TBM and Drill and
Blast tunnelling, primarily, for the two main tubes. The underground works involved constructing a
total of approx. 22.5km of main tunnels plus 38 cross passages (approx 2.3km in total), and completion of the Emergency Stop (mostly built in Lot H33). Access underground was via Ahrental adit - itself built earlier, in the E41 Exploratory Lot, over 2010-12. The Ahrental Access Tunnel and Innsbruck Emergency
Stop arrangement created a T-junction, in effect, on either side of which different tunnelling methods were employed: to the south side of the Emergency Stop the main tubes had TBM launch chambers constructed, from which two shields bored southwards, towards Lot H53; to the north side of the Emergency Stop the main tubes only would be blasted towards the Innsbruck portal, and tie-in to the H21 works. The Ahrental adit allowed short, initial portions of
the main tubes to be blasted, in 2015. This readied the location for tie-in of other tunnels, such as from H33, and to proceed later from the area. The JV contractor launched the two 10.4m-diameter
single-shield TBMs on their drives south from Ahrental starting in May 2023. TBM ‘Lilia’ would drive 8.1km southwards for the East main tube, and sister shield ‘Ida’ would bore 8.4km for the West main tube. The TBMs very recently completed their drives - ‘Ida’ in late August 2025, and ‘Lilia’ in early October. For the Drill and Blast works, the JV excavated
distances of 2.3km and 3.4km for the East and West main tubes, respectively. Tunnel blasting for the East tube finished in September 2024 and for the West tube the excavations were completed in May 2025. The H41 package did not include much exploratory
tunnel works. The northern portion had been built already, and the H33 Lot built the stretch at Ahrental and extended it much farther south.
28 | December 2025
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