TBM Ida has reached her halfway point: on 22nd July 2024, she completed the excavation of the first 4 kilometres along the west line tunnel as part of the Austrian construction lot ‘H41 Sill Gorge-Pfons’.

Ida’s journey is progressing smoothly: her determination to continue through the heart of the mountain, at a depth of approximately 1000 metres, has already brought the Austrian tunnel boring machine past the fault zones known as ‘Viggartal’ and ‘Walzn’. Today, the TBM is practically halfway: the total length of the planned excavation is 8.4 kilometres, so today Ida is just over 4 kilometres away from her goal.

The stages of Ida’s Journey, from February 2023 today

Ida’s journey started from afar. The tunnel boring machine (TBM) was inspected and tested in February 2023 at the Herrenknecht plant in Schwanau, Germany. After the factory test, the TBM was disassembled and transported to the west assembly chamber of the H41 Sill Gorge-Pfons construction site. The dismantled parts of the TBM were brought to the construction site and, after reassembly, the TBM was prepared to move southwards through the west main tunnel.

She is one of the largest TBMs on the entire site, with a cutter head diameter of 10.37 metres, a length of around 160 metres and a weight of 2,420 tonnes (including the back end). In June 2023, she finally set off on its journey southwards along the west main tunnel, where she will reach the town of Navis.

TBM Ida not only excavates, but also installs the final tunnel lining

"Ida can do a lot. For instance, her cutterhead can rotate and extract rock from the mountain. And she can also install prefabricated tubbing rings in the tunnel”, declared the third-grade students at the Navis elementary school in a video made last year during the TBM's start-up ceremony.

And it's all true. These delightful friends, who chose the name “Ida” for the TBM, pointed out that the machine doesn’t just move southwards, excavating the tunnel, but also installs the tunnel’s inner lining.

So far, some 22,300 tubbing rings have been laid in the two main tunnels. All of the tubbing rings were produced by the site’s own factory, thus sparing the environment the approximately 27,000 heavy vehicle transports required to move the tubbing rings.

Best of luck to Ida for the next 4 kilometres.  The challenges of mechanized excavation and tubbing ring production continue under the banner of three key principles: perseverance, efficiency, and environmental sustainability.

source: BBT-SE