The western coast of Norway is home to some of the most dramatic landscapes on earth.
Carved by glaciers throughout the ages, some of these fjords stretch for 200 kilometres
inland and are over a kilometre deep.
The current convoluted travel route through and around this terrain takes you along Norway’s
1,100 kilometre, 683 mile, E39 highway.
A road with a total journey time of 21 hours.
Now, the Norwegian government are working to improve access to services and residential
and labour markets across the country’s western regions by embarking on the largest
infrastructure project in the nation’s history.
Norway’s E39 highway runs between, Kristiansand
in the far south of the country and Trondheim in the north.
The route navigates its way
across the fjord network and features no fewer than seven ferry crossings.
The new coastal highway project aims to eliminate the need for ferry services altogether by
building a series of bridges and tunnels across, through and under the landscape.
With many of the fjords along the route being too wide or too deep for conventional infrastructure
to cross, innovative new solutions are being investigated by the Norwegian Public Roads Administration.
Rogfast is the first in a series of crossings that will link the E39, connecting Stavanger
and Haugesund via a 27 kilometre, 16 mile, under sea tunnel.
This structure will reach depths of up to 390 metres below sea level, making it the
deepest as well as the longest undersea road tunnel in the world.
The Rogfast project will in fact consist of two tunnels connected every 250 metres with
emergency exits.
Each tunnel will have a lay-by at 500 metre intervals, along with telephone
and surveillance cameras along the route.
The tunnel will also feature a mid-route intersection with the island municipality of Kvitsøy creating
an undersea tunnel junction and connecting the island with the Norwegian mainland.
With work begun in 2018, this element of the project is set to be completed by 2026 at
a cost of USD $2BN.
While the Rogfast works are already underway, the scale of some other fjords is presenting
the project team with extreme engineering challenges.
Bjornafjord - located to the south of Bergen - stands 5 kilometres wide, and reaches depths
of 600 metres.
To cross this challenging stretch of water, a proposal has been put forward for a floating
bridge, anchored to the shore at both ends.
The Sulafjord crossing has seen two possible solutions put forward.
The first is for a three tower suspension bridge, with two of the bridges’ towers
anchored on land and the third central tower anchored to the seafloor, some 400 metres
below the water line.
An alternative proposal for a “submerged floating tunnel” would see two interconnected
tubes running side by side tethered to the seabed using high strength cables.
Crossing the Romsdalsfjord will require a 16 kilometre undersea tunnel, much like the
Rogfast project, from Alesund to Midsund - followed by a 2 kilometre suspension bridge connecting
onto Molde.
By far the most complex and ambitious of all of the coastal highway crossings is that at
Sognefjord - also known as the “King of the Fjords”.
Norway's largest and deepest fjord is over 3.7 kilometres wide and an incredible 1.3
kilometres deep at its lowest point.
While these extreme distances pose their own challenges, engineers must also account for
the high number of ships that enter the fjord on a regular basis.
Any crossing must allow for a clear shipping lane that is at least 400 metres wide - with
70 metres clearance above the water’s surface and at least 20 metres clearance into the
depths.
To deliver this, the project team are considering numerous different types of crossing for this
fjord.
The first is a traditional suspension bridge. With a 3,700 metre crossing, such a structure
would be almost double the length of the world’s current longest bridge and would require support
towers at least 450 metres tall, significantly eclipsing the 343m tall Millau Viaduct in
France to become the world’s tallest bridge structure.
A floating bridge is also being considered. However, this structure would need to raise
to allow ships to pass and achieving such a feature in a bridge that is only anchored
to each shoreline poses considerable engineering challenges that are yet to be overcome.
In a similar proposal to that found at Sulafjord, a submerged floating tunnel in also being
considered.
This proposal would differ slightly to its counterpart due to the extreme depth of the
Sognefjord. Rather than being tethered to the seabed, the tunnels would be suspended
from floating pontoons that would allow ships to pass overhead.
A hybrid proposal is also being considered - combining a floating pontoon bridge with
a portion of submerged floating tunnel that allows ships to pass.
Whilst fixed bridges transferring into fixed tunnels is not an uncommon solution in waterways
with high shipping traffic - such as the link between Denmark and Sweden and the extensive
Hong Kong to Macau crossing - combining the two floating structures in this way would
create the world's first example of such a solution.
Finally, a proposal for a multi-span cable stayed bridge is under review.
This structure would feature four floating pylons tethered to the sea floor rather like oil rigs.
With safety and environmental considerations being of the utmost importance, Norway’s
vast coastal highway project is set to become a new benchmark in engineering capabilities
and a model for future infrastructure projects around the world.
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