The Halsnøy tunnel is a 4,1 km long sub-sea road tunnel between Sunde at the mainland and Tofte at Halsnøy in Hordaland.
 
Overview over the tunnel alignment

The Halsnøy connection between the mainland and the island Halsnøy will give 2.300 people a better connection to the mainland.  The connection consists mainly of a sub-sea road tunnel, Halsnøy tunnel, witch will be 4,1 km long and have a width of 9 m. The deepest part of the tunnel will be 136 m below the sea level. The tunnel is under construction as a drill and blast tunnel in gneiss and mica schist.

NGI's work have consisted of geological mapping, design of core drilling, core logging, estimation of rock support and grouting and preparation of tender documents.

Example on a crushed zone

Client: Norwegian Road Authority
Project year: 2003-2004
Project cost: NOK 356 million