The road tunnels form part of the E39 European highway between Trondheim city in Norway and Ålborg in Denmark, and in 1992 the Byfjordtunnel was the world’s longest undersea tunnel, 5.875 meters long and lowest point is 223 meters below sea level. The Mastrafjordtunnel is 4.424 meters long 133 meters below sea level.
A Systemair spokesman added: "More than 20 years after they first opened, these tunnels have been fully refurbished with new safety equipment. Systemair Norway has been a part of this refurbishment and has contributed on several levels. The fans were produced at Systemair in Germany. The tunnel has been open for traffic during the complete refurbishment period. The project’s order value is close to EUR 2M (USD 2.2M)."
