Norconsult
Rogfast will be the deepest tunnel in the world
Already under construction, Rogfast, in Norway, will be the longest and deepest underwater tunnel in the world, stretching 27 kilometers off the country’s western coast. With two parallel galleries, it will have a double rotunda 260 meters deep.
Norway is involved in building one of the most ambitious infrastructures in its recent history. Its engineers designed a tunnel with two parallel galleries, 27 kilometers long, which will descend to 392 meters below sea level, becoming the underwater road tunnel longer and deeper of the planet.
If there are no delays, the tunnel, which has been named Rogfast — abbreviation of Rogaland landline, the name of the region followed by the Norwegian word meaning “fixed connection” — should be completed in 2033.
The tunnel will be one of the fundamental parts of the E39 coastal highway, a 1,100-kilometer axis that connects Trondheim, in the north, to Kristiansand, in the south of the country. Today, traveling this road involves 21 hours of travel and the use of up to seven ferries.
The purpose of this bridge and tunnel system is completely eliminate ferries and reduce the travel time in half. But this should only happen, according to the promoters’ most optimistic estimates, around 2050note or .
“The tunnel will significantly improve connectivity along the west coast of Norway by creating a faster and more reliable connection between the Stavanger and Haugesund regions,” he explains. Anne Brit Moenproject director at , the construction company responsible for works in the northern part of the tunnel, the deepest section, measuring 9 kilometers.
The construction started in January 2018but was discontinued at the end of 2019 due to cost overruns which led to the cancellation of existing contracts and a restructuring of the project.
Work resumed at the end of 2021 and is estimated to be completed at an approximate cost of 25 billion Norwegian kroner (around 2100 million euros).
The tunnel will have two separate galleries, each with two lanes, designed exclusively for car traffic.
It will also have a unconventional design element halfway through: one double roundabout 260 meters deepwhich will connect to an access tunnel to the island of Kvitsøy, the smallest municipality in Norway.
Like most modern tunnels, Rogfast is being excavated simultaneously from both endsto save time, which requires the two construction teams meet halfway with a margin of error of just 5 centimeters.
This limit, Skanska engineers guarantee, is one of the most demanding in the world, but allows you to save a lot of time, moneywaste and emissions — as long as deviations are avoided.
Carrying out a project of this type hundreds of meters deep under the sea is a constant puzzles.
“We are now 300 meters below sea level and we have already had infiltrations quite significant amount of salt water in the tunnel system. As we will descend to 392 meters below sea level, we are focused on finding the best methods to ensure safe working conditions and efficient for everyone”, highlights the project director.
The tunnel will integrate measures to protect drivers from pollution from the air. It will have a longitudinal ventilation system with reaction fans to create airflow, which will work in conjunction with a ventilation system.
“This combination was designed to guarantee a effective air circulation and security along the considerable length of the tunnel”, notes Moen. There will also be a camera and radar system monitoring in real time vehicles to detect potential breakdowns or congestion.
Although Moen recognizes that they will lose jobs with the end of ferries, believes that the region will be compensated for other opportunities. The project director guarantees that the tunnel will facilitate access to other jobsas well as education and public services for local communities.
Rogfast will also have, he says, positive effects on the local economy and in the fishing industry, as logistical costs will decrease and companies will be able to operate in a wider area.
“The project also creates a lot of jobs during the construction phase and lays the foundation for a more sustainable regional development and integrated along Norway’s fragmented western coast,” says Moen.
Although Rogfast is the deepest tunnel, the title of longest tunnel in the world with an underwater section belongs to tunnel Seikan. Located in northern Japan, it is used exclusively for rail transport and has a total length of 53.85 km, with an underwater section of 23.3 km.
O Eurotunnelwhich connects England to France, is shorter, at 50.46 km, but its underwater section, at 37.9 km, is longer than that of Rogfast. The Norwegian tunnel will, however, much deeper than the Seikan or the Eurotunnel, which are located, respectively, 240 meters and 115 meters below sea level.
