PROJECT | ROCK TUNNELS


H61 - MULES 2-3


Immediately south of the border, and dominating the Italian side of the tunnelling works for the Brenner Base Tunnel, is Lot H61, Mules 2-3 (Mauls 2-3, in German). It is also the largest construction package on the entire project. Started in late 2016, it has been undertaken by a JV of Webuild (which holds the previous contractor on the Lot, Astaldi (until 2021)), Ghella, Oberosler Cav Pietro (up to mid-2018), Cogeis and PAC. The contract package includes the works for main


tunnels, the Mules Emergency Stop, cross passages, a long section of exploratory tunnel, and access and logistics tunnels. All excavations have been completed, except for


some cross passages, and final lining works which are underway. Well in advance of those works though was some


early tunnel construction - for the Mules access tunnel over 2007-9; and, the southernmost portion of the exploratory tunnel, over 2008-10. Altogether, preparatory works took place over 2008-11, then more underground works for various tunnels, under Lot Mules 1/Mauls 1 (also called Exploratory Lot E62), were performed over 2011-15. Thereafter, Mules 2-3 would hold the main tunnelling works to be execute for the project. Mules adit is in the area where two tectonic plates


(European and African) press together as the Periadriatic Seam, making the locality one of the most important fault zones in the Alps, says BBT-SE. The adit was on one side of the fault zone and on the other was the future location of the Trens Emergency Stop’s large tunnels. Early works, therefore, were undertaken to carefully explore the fault zone and firmly open up the short stretches of the main tubes and the exploratory tunnel that were to pass through. Those excavations were performed by mechanical diggers over late 2011 to mid-2015.


The southern end of the exploratory tunnel was bored


by a 6.3m-diameter double-shield TBM, launched from the south portal at Aicha (Italian) or Aica (German) which is off the alignment of the Brenner Base Tunnel. The TBM bored northwards through Brixner granite for about 10.4km from mid-2008, coming into the main tunnel alignment and finishing, near the Mules/ Mauls Access Tunnel, in late 2010. The works were performed by Seli (now part of Webuild), as part of a JV with Pizzarotti, Bilfinger Berger, Alpine, Beton -und Monierbau, Jager, Collini, and Condotte. With completion of those early works completed,


preparations continued for the main tunnel and associated works to follow, in Lot H61. In early 2017, soon after the Lot was awarded, one


of the tasks was to build a 3.8km-long branch tunnel from Mules adit. The branch ran parallel to the main alignment of the Brenner Base Tunnel and then turned in to the location of the future Trens Emergency Stop. Benefits of the branch would be two-fold: access during construction; and, backup in the operational life of the Base Tunnel. The branch tunnel was completed in mid- 2020 and works began to open up the Emergency Stop and other tunnels. Final lining works for the Emergency Stop were completed in mid-2025. It was also in 2017 that excavations for two main


tunnels began, with faces blasting in opposite directions from Mules adit. But blasting would only continue on the south side, as far as the boundary with the project’s southernmost Lot, H71 (Isarco River Underpass, and portals). Excavation of H61’s south tunnels finished in late 2020. To the north side of the adit only a short distance of


blasting was performed and double-shield TBMs were then launched to complete the main tunnels up to the border with Austria. The two northbound drives started in mid-2019. TBM ‘Virginia’ finished the 14.2km-long drive (East main tunnel) in early 2023, and ‘Flavia’ (West main tunnel), having had a brief difficulty at a fault zone, completed in May 2025 - marking the end of TBM tunnelling on the Italian side of the project. The remaining tunnelling works in the Lot were for


a portion of exploratory tunnel, extending northwards from Mules adit and Emergency Stop tunnels area. The tunnel was bored by 6.8m-diameter double-shield TBM ‘Serena’, which was launched on the 14km-long drive to in mid-2018 and finished in late 2021. In September, the Lots H53 and H61 achieved final


breakthrough on the exploratory tunnel, marking finally the end of excavation on the tube. It is the first tunnel where excavation has been completed fully on the Brenner Base Tunnel.


December 2025 | 33


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