Kaprun 2029: A Giant Leap for Hydropower with TBM Technology

The Kaprun 2029 project has reached a major milestone with the launch of a tunnel boring machine (TBM) on February 18, 2025. The 5.6km pressure tunnel, a critical component of Austria’s €370 million hydropower modernization initiative, will secure the long-term energy supply for the Kaprun-Hauptstufe power plant by transporting water from the Wasserfallboden reservoir to the facility in the valley.

With an excavation rate of 15m per day, the TBM is expected to complete its journey to the new surge tank within a year. The machine, previously used in Limberg II and III projects, has been upgraded with a 100-tonne cutterhead, fitted with 42 cutting rollers, each weighing 130kg.

The TBM, measuring 190m in length and weighing 1,200 tonnes, was transported in 90 separate shipments and assembled inside an underground cavern over eight weeks. Engineers and geologists carefully planned the excavation process, ensuring that geological conditions were well understood before the project commenced.

A sophisticated rail system will be installed inside the tunnel to streamline excavation, while 200,000m³ of excavated material will be efficiently transported via conveyor belts to a transfer station before disposal.

The Kaprun 2029 project reflects Austria’s commitment to renewable energy, ensuring the continued efficiency and flexibility of hydropower. The new headrace tunnel, set for completion by 2027, will enhance energy stability while minimizing environmental impact by conducting most of the construction work underground.

The project marks another step forward in modernizing hydropower infrastructure, demonstrating how advanced TBM technology and sustainable engineering are shaping the future of energy production.