Backers of the 19km Fehmarnbelt Crossing between Denmark and Germany have confirmed that they will recommend the tunnelled option over the bridge proposal, despite recently lauding the benefits of the latter.
Promoter Femern said that an immersed tunnel was less risky to build and operate the alternative cable-stayed bridge proposal, despite the bridge being called “iconic” by the firm.
Both options faced technical risks relating to environmental impact, navigation safety and construction cost.
These were the key factors in choosing the tunnel option, although the promoter’s decision remains provisional pending an Environmental Impact Assessment (EIA).
A final political decision on which of the two will be selected will be made in early 2011.
It is anticipated that the preferred solution will form the basis for the project application to be submitted to the German authorities.
The project will be officially sanctioned via Danish legislation and subject to approval by the German authorities.
Construction contracts are not expected to be signed until 2014. It will be up to contractors to organise the work, including the location of the large production sites for manufacturing bridge or tunnel components.
Femern said it had assumed that a large proportion of the steel structures for a bridge would be constructed in the Far East – possibly China – while tunnel components would be produced locally owing to their weight. Femern said that production of concrete components should ideally be sited up to 120km from the route corridor.
A more distant siting may also be considered if contractors conclude that this would be more financially competitive.
In financial terms, there is very little difference between the two projects.
The construction estimate (2008 price level) for an immersed tunnel is €5.1bn (£4.27bn) and for a cable-stayed bridge £4.35bn. The construction time for the tunnel is estimated at six and a half years, and for the bridge, six years.