Milestones Reached at Brenner Base Tunnel

BBT SE announced on July 19 that the last ring came off the line at the factory in Ahrental which made the prefab concrete elements for the nearby “H41 Sill Gorge-Pfons” construction site, for the Austrian stretch of the Brenner Base Tunnel.

The plant had gone into operations in February of 2023 and since then has produced just over 59,000 tubbing rings, meaning a daily production rate of approximately 90 prefab pieces. The tubbings are the final lining of the main rail tunnels and are laid by the TBMs, which besides the excavation also install the final tunnel lining.

The Ahrental construction site had no rail line for material supply. For this reason, the temporary consortium carrying out the works, ARGE H41, chose to produce the rings directly on-site. Production was organized on a line thanks to an innovative set-up which divided the work into phases: molding, reinforcement, concrete and curing. An internal transportation system ensured continuity, optimizing timing and costing and guaranteeing high quality standards. After storage, the tubbing rings were carried into the heart of the mountain, down to one thousand meters above the surface, using a specially developed vehicle and then a special train. Finally, the rings were installed by the TBMs.

If the rings had been produced elsewhere, transportation to the construction site would have required about 29,500 truck trips. With this efficient and sustainable solution, only 3,000 trips took place, which were necessary to supply construction materials and the reinforcement steel.

“Thanks to this on-site production, tens of thousands of lorry trips were avoided”, explains Romed Insam, project manager for Lot H41 Sill Gorge-Pfons. “This meant not only far less disturbance for the surrounding communities, but also shows that modern infrastructure projects can be carried out efficiently and yet respect the environment”.

Marco Reith, Project Manager for Implenia, ARGE H41, is pleased with the goals that have been achieved: “Thanks to Implenia’s experience and the close cooperation with BBT SE, we were able to produce extremely high-quality prefab shotcrete elements, and do it in a sustainable manner. This was to the benefit of local companies as well, since they were our suppliers. Once production ends, part of the plant will be used to produce steel reinforcements.”

Meanwhile, tunnel boring on the lot is nearing the finish line. Two Herrenknecht TBMs, Ida and Lilia, have both been operational since the summer of 2023 and will travel just under 17 km when they reach the end of their journey in the township of Navis. The two machines are advancing southwards towards the neighboring H53 Pfons-Brenner lot.

Herrenknecht announced in late August that TBM Ida successfully completed its drive. Lilia is expected to complete its drive this fall. This would complete all mechanized excavation work for the construction lot H41 Sill Gorge-Pfons – the next milestone toward the completion of the Brenner Base Tunnel.

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