The Stad Ship tunnel, Norway

The North-West coast of Norway is a rough and potentially dangerous area for sea traffic. To reduce current hazards, the Norwegian Coastal Development Authority is considering proposals for a ship tunnel, aiming to provide protected passage and minimize journey time in the highly exposed Stad area.

Certain parts of the north-western coastline off Norway pose a significant challenge for ships during severe weather. One of the major obstacles is the passage west of the Stad headland, midway between Bergen and Trondheim. Many vessels have met their fate in this harsh and exposed area between the North Sea and the Norwegian Sea. During storms, coastal freighters commonly wait in port either side of Stad. Incidents and accidents, as well as the uncertainties and the waiting, led to the idea that the way to secure safe and regular passages would be a tunnel through the headland.

Several studies have been conducted over the years, all suggesting that the project is feasible, and foreseeing few technical obstacles. The planned tunnel will connect the Moldefjord to the Vanylvsfjord, a distance of about 1.8km.

The Norwegian Coastal Development Authority is currently evaluating a tunnel designed to carry ships of several thousand tonnes, but not the biggest carriers. A width of 36 metres, and a height of the roof 37 metres above sea-level, and the water depth will allow a draft of 12 metres.

Numerical modelling with rock support bolting

Cross section for the planned rock tunnel

NGI provides engineering geology expertise
Significant amounts of rock will have to be excavated and disposed of. NGI has been engaged to evaluate the rock mechanics aspects related to such excavations, based on long time experience with planning and design of large rock caverns for the hydro power industry and, transportation and infrastructure, both in Norway and internationally. The Stad tunnel project is regarded as straightforward in terms of construction and engineering.