HYDRO Exploitation SA

06/23/2026 | Press release | Distributed by Public on 06/22/2026 22:27

Refurbishment of the Great St Bernhard Tunnel Turbine

The Great St Bernard Tunnel connects Switzerland with Italy. Situated 1.5 km from the entrance on the Swiss side, a hydroelectric power plant built into the tunnel was constructed by les Ateliers de Vevey and commissioned in 1962. The system uses water from a dam located 170 metres higher up, a reservoir designed primarily to supply the tunnel's fire protection system. The plant produces 3.2 GWh per year.

Complete refurbishment of the turbine

In January 2026 HYDRO was commissioned to carry out a complete overhaul of the turbine, including all hydraulic, mechanical and safety components. The engineers fully dismantled the installation on site, then brought all the components back to the central workshops in Martigny. The following works were carried out:
  • Complete restoration of anti-corrosion coatings on all parts
  • Repair or refurbishment of multiple components (electrolysis, chrome plating, welding, non-destructive testing, grinding of main rods, replacement of needles and mouthpieces, changing all seals, cleaning, etc.)
A boost of 15 kilowatts to output

A pressure test was carried out in early April 2026, which showed the installation was fully watertight, before it was put back into service in mid-April in line with the original schedule. The boost to output is estimated to be 15 kW. HYDRO's completion of this service guarantees the hydroelectric plant's reliability, efficiency and complete suitability for the tunnel's future operating requirements.

A unique installation built into the tunnel

This plant is the only example of a hydroelectric generation facility being built into the heart of an international tunnel. Six experts are responsible for the annual maintenance and technical monitoring of the facility, while 25 fire-fighters and operators oversee the tunnel and manage the fire system, which is closely linked to the dam and turbine.

HYDRO Exploitation SA published this content on June 23, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on June 23, 2026 at 04:27 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]