Wedoany.com Report-Feb 21, A tunnel boring machine (TBM) has begun work on a new 5.6km pressure tunnel as part of the modernization of VERBUND’s Kaprun-Hauptstufe power plant. The launch took place on February 18, 2025, with the traditional miner’s greeting ‘Glück Auf.’
The event, known as the ‘turning ceremony,’ marked a key milestone for the ‘Kaprun 2029’ project. Around 200 guests attended as VERBUND hydropower management representatives Michael Amerer and Karl Heinz Gruber, along with tunnel patron Kathrin Aberger-Dick and ARGE representatives Jürgen Raschendorfer (COO Porr AG) and Bernd Raderbauer (Marti Tunnel AG), initiated the TBM’s cutterhead rotation. The new headrace is expected to be completed by the end of 2027, ensuring the continued safe and efficient transport of water from the Wasserfallboden reservoir to the power plant.
The TBM being used for this project was previously deployed in the Limberg II and Limberg III projects. Key components, including the 100-tonne cutterhead with a 6.90m diameter, have been replaced and adapted. The entire TBM measures 190m in length and weighs 1,200 tonnes. Transporting its components required 90 separate deliveries to the assembly cavern, where it was put together over eight weeks.
VERBUND Hydro Power Managing Director Michael Amerer emphasized the historical significance of the project, stating: “We are continuing on the path taken by the heroes of Kaprun after the Second World War for the reconstruction of Austria. Today, we have driven the first metres of the new pressure tunnel – an important moment for VERBUND. This pressure tunnel is the centrepiece of our project, which will upgrade the entire power plant to the latest state of the art by 2029, so that we can continue to supply all of Austria with green electricity and efficient flexibility from hydropower in the future.”
Project Manager Maria Leo noted the careful planning that preceded the tunnel boring process. “A launch celebration is always something very special. We are pleased that the preparatory work has gone so well and that it is now starting. The geological conditions for the advance are well known and the tunnel boring machine and the team are already familiar with our mountains from previous projects. Almost all of the work will be carried out underground. This means that the impact of the construction work is reduced to a minimum.”
Tunnel patron Kathrin Aberger-Dick spoke about her personal connection to the region. “I have close ties with the mountains in Kaprun and grew up with the high-altitude reservoirs. It is therefore a special honour for me to accompany the construction phase as the earthly representative of Saint Barbara, the patron saint of tunnel builders and miners. I hope that the underground work remains free of accidents and that the tunnel boring machine reaches its destination as smoothly as possible.”
Tunnel excavation and logistics
The TBM will advance at an average rate of about 15m per day, reaching its destination at the new surge tank in about a year. The pressure tunnel will have an incline of 0.50% and a 6.90-metre excavation diameter.
The excavation process requires managing approximately 200,000 cubic meters of removed material. The rock is broken into small pieces by the cutters and transported out of the tunnel via conveyor belts to a transfer station at the Limberg valve chamber. From there, it is moved through the existing tunnel system to a disposal site in the valley. This system helps minimize construction-related traffic and reduces the impact on the surrounding area.
VERBUND is investing approximately €370 million in the ‘Kaprun 2029’ project, which aims to upgrade the power plant with modern technology to ensure reliable and sustainable energy production for the future.
