The tunnel will improve traffic flows in the city centre and will form part of European Route 39, one of the main traffic arteries on Norway's southwest coast. It will be built by a joint venture in which Bilfinger holds a 60% stake and the Norwegian company Stangeland has 40%.
Work on the approximately 5km-long twin tube tunnel includes construction of several access ramps as well as further connector tunnels. A 2.5km-long new motorway section will also be built as will bicycle and pedestrian paths.
Bilfinger will carry out the underground construction and Stangeland will assume responsibility for earthworks and road construction.
The project is due for completion in 2018.