On April 5, the Norwegian government approved the world’s first ship tunnel, a bold scheme to cut a passage through the bottom of the Stad peninsula. Procurement of the $315-million project could start in 2019 or 2020. Three to four years’ construction would follow.

Passing up to 350 meters below mountaintops, the 1.7-kilometer-long Stad tunnel is planned to be 49 m tall and 36 m wide, calling for some 3 million cu m of hard-rock excavation. With both sides set at sea level, the maximum water current flowing through the tunnel is forecast to be 2 knots, says Terje Andreassen, project manager with the Norwegian Coastal Authority (NCA).

Having secured backing for the concept in the country’s next National Transport Plan, the Norwegian Coastal Authority next month aims to submit its final technical proposal for government approval. NCA completed initial feasibility studies in 2012, supported by Norwegian design firms Norconsult A.S., Sanvika; and Dr.techn.Olav Olsen A.S., Lysaker.

While drilling and blasting the tunnel should pose no trouble to Norway’s seasoned hard-rock tunnelers, materials handling will be the main challenge, says Andreassen. Using the heading and benching method, tunnelers will need to work on more than one level at a time, he says, adding, “We will leave that for the contractor to decide.”