Eiksund undersea tunnel

Eiksund undersea tunnel is the world's deepest tunnel.

The 7,765 m long Eiksund road tunnel in Norway is, to date, the world’s deepest undersea tunnel, reaching a depth of 287 m below mean sea level at its deepest point. When completed it will connect the Norwegian mainland with the offshore islands of  Eika and Hareid, Herøy, Sande and Ulstein.  As with all undersea tunnels, salt water seepage tends to be corrosive and for long life, special rock bolts need to be used.  In Norway CT Bolts are almost always specified for undersea tunnel sections as they are designed to have a 50-year life in aggressive environments.  For the Eiksund tunnel standard Combi-Coated Ørsta resin anchored bolts are in use as regular support and Combi-Coated M20mm CT Bolts are used where there are poor rock conditions and for systematic permanent support.  Altogether it is anticipated that some 10 000 CT Bolts will be used on this project.

 

Bolting in the Eiksund tunnel