Ida completed her first 4-km stretch on July 22nd, and TBM Lilia is keeping up with her sister. Exactly two months later, the tunnel boring machine that is excavating the east line tunnel at the H41 Sill-Pfons Gorge site has also completed her first 4 km. Not an easy journey - Lilia has already successfully driven through the ‘Viggartal’ and ‘Walzn’ fault zones - but this huge multifunctional machine deep in the heart of the mountain is now very close to her halfway point. The total length of the planned stretch is in fact 8.1 kilometres, so today just over four kilometres separate Lilia from her finish line, located in the municipality of Navis.
The stages of Lilia’s journey, from December 2022 to today
Lilia was inspected and tested in December 2022 at the Herrenknecht plant in Schwanau, Germany. After the factory test, the TBM was disassembled and transported to the east assembly chamber of the H41 Sill Gorge -Pfons construction site. Finally, on 2 May 2023, Lilia began her journey through the east line 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 so-called back-up).
On-site tubbing ring production: an environmentally friendly process
“Lilia isn’t only excavating a tunnel through the mountain. In fact, she is also laying the tubbing rings which form the final concrete lining of the tunnel,’ explains Christoph Waldhör, technical coordinator of the H41 Sill-Pfons Gorge site.
That's right. So far, Lilia has laid more than 14,400 tubbing rings, produced in the on-site plant. The presence of a plant for tubbing ring production directly on the construction site is not a minor detail, as it allows a huge reduction in CO2 emissions. In fact, some 27,000 trucks would have been needed to transport the tubbing rings from a factory to the construction site. As the plant is located directly on the construction site, this environmental impact is mitigated.
What now? Lilia still has four kilometres ahead of her, Ida just over three. Together they are moving towards their goal, to complete machine-driven excavation of the tunnels southwards in an efficient and environmentally sustainable manner.
