Two subsea tunnels totalling 20km in length have been given the green light by the Norwegian Government.
The estimated US$1 billion dual carriageway road tunnels, which have been subject to alignment changes, geotechnical and seismic studies for 35 years, are to be financed partly by regional and national government sources, but mostly by toll income.
Aerial view over Stavanger and Strand
Fig 1. Alignment for 20km subsea tunnels
Commenting on the announcement by the Norwegian Highways Department, the Norwegian Tunnelling Society described the mega-project as technically challenging. Parliament is expected to ratify the Cabinet's decision to progress the Ryfast Project to a construction tendering phase later this month. Procurement and construction of this most ambitious of Norway's long list of undersea tunnels is on scheduled for completion and an opening to traffic in 2018.
Norwegian Roads Authority (Statens Vegwesen) Project Manager Geir Tor Espedal said: "This is a breakthrough for Ryfast. We are looking forward to the start of construction. Many questioned this project but the thorough preparation work that has been carried out has proved decisive. The contracts for construction are so large that we expect interest from foreign companies."
The project comprises two linked undersea tunnel sections:
• The 14.3km Solbakk tunnel linking Solbakk and the ferry port at Tau in the Strand municipality, and the island of Hundwåg, via an alignment under the small island of Hidle where a ventilation shaft is planned. At its deepest point it will sit 290m below sea level, with an average depth below the sea of 50m (Fig 2), making it the deepest and the longest of all Norway's subsea tunnels.
• The 5.7km Hundvåg tunnel which will link Hundwåg and the mainland city of Stavanger on the west coast of Norway, with an exit ramp at Buøy (Fig 3).
Fig 2. Solbakk tunnel cross section
Fig 3. Hundvåg tunnel cross section
Engineering design consultant Norconsult completed the alignment and planning studies earlier this year and will be involved in the tendering process, which is expected to start in Autumn this year.
At Stavanger the subsea tunnels are planned to connect with a new 3.9km road tunnel that already has secured funding and is due to be constructed on the main E-39 highway. Once all the tunnelling work is complete the ferry service that currently links Stavanger and Strand will cease.
Norway is the world's leader in construction of subsea highway rock tunnels, with more than 29 in operation and others in design and construction. The country's first undersea road tunnel, the 2.6km Vardø link above the Arctic Circle, opened in 1981.
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