
The first floating underwater submersible tunnel in the history of civilization: technologies, features, prices
Humanity is in a hurry: running to work, galloping to rest. Mobility has reached an incredible level. The steering wheel and pedals seem to be becoming additional organs of homo sapiens. Land vehicles require roads. And here on the way there is a mountain, then a strait - a headache for the guys in orange vests. But these guys do not give in: they are developing a complex, labor-intensive, expensive branch of the national economy. Next to them, technology, mechanisms, tools are being improved.
Road builders, driven by the rush of humanity, are coming up with new ways to reduce the distances between populated areas and industrial facilities. They figure out how to make travel comfortable and deliver cargo quickly. To do this, they smooth out terrain, build bridges, and bite into rock formations. The industry is rich in discoveries, innovations, and fantastic technologies. And here is a fresh example – the Scandinavians with their floating tunnel.
Norway – a prosperous, rich state with unique nature. Tourists come here to admire, among other things, the stunning fjords. Narrow sea bays cutting deep into the land are not only the country's heritage, but also an eternal problem. For road workers, first of all.
Computer visualization of a floating submersible tunnel element. Photo: YouTube.com
The international highway number E39 runs along the western coast of the country. The route connects Trondheim in Norway with Aalborg in Denmark. Its length is not the largest – 1330 km. In principle, it is possible to cover the route on the car in 10-11 hours is a task that any driver can handle. You can drive slowly, observing speed limits and making stops for a snack or to contemplate the same beauties.
In fact, the minimum a motorist can expect is 23 hours. The thing is that you need to cross 9 fjords by ferry. At the same time, law-abiding citizens will have to wait in line, follow the unwavering schedule of disciplined carriers, and spend extra money. These circumstances complicate the trip and irritate drivers.
Schematically, the submersible floating tunnel will look like this. Photo: YouTube.com
Adding to the inconvenience are the two E39 road lanes, which are unwilling to accommodate the ever-increasing flow of cars. The Norwegian government, obliged to respond to challenges, has instructed the Public Roads Administration to sort out the situation. Especially since it is too expensive for the government to maintain an entire ferry fleet.
For example, in Hordaland, located south of Bergen, there are 5 ships transporting cars. But the queue does not dissipate. The work of the ferry crossings, let us remember, directly depends on the weather. And it is very unstable in the polar regions.
Ten years ago, the said Department developed active activities. First: it is necessary to modernize the international highway, adding a couple more lanes. The usual duties for the Orange Vests. Modern technologies allow road repairs to be carried out on kilometer-long sections without stopping the traffic flow.
Fjords lengthen Norway's road network. Photo: YouTube.com
Second: where conditions allow, the banks of the fjords will be connected by bridges of various configurations. However, given the soil conditions and seismic activity of the region, bridges are not a panacea everywhere.
Thus, it is impossible to build a bridge between Stavanger and Bergen, the country's major cities. The strait is deep - more than 300 m. It was decided to build an underwater concrete tunnel here.
It is difficult to count similar cases in international construction practice. Such tunnels have been built successfully for a long time: from 30-meter pedestrian to 53-kilometer railway. Basically, they run along the bottom. There are few examples below this level: the Eurotunnel under the English Channel, the Japanese Seikan.
Ferries across the fjords. Photo: YouTube.com
The length of the Norwegian tubular tunnel with a diameter of 10,5 m should be 27 km. The depth is 392 m, i.e. below the bottom. Three threads need to be laid: two for movement Transport in different directions and one service.
The contractor prepared the design documentation, received parliamentary approval in 2017, and received 1,73 billion euros in funding. The contractor, Rogfast, promised to start running cars through the underwater pipes by 2026. However, the first explosion of coastal rocks at the construction site in January 2018 blew both the technical and economic justifications of the project to pieces.
Work on the construction of underwater tunnels begins on the shore. Photo: YouTube.com
The reality turned out to be more complicated than it looked on paper and on the computer. To the credit of the Norwegians, they suspended construction, adjusted plans and started again in 2020. Now the budget has increased to 2,55 billion euros, and the commissioning dates have been pushed back to 2028.
However, these were not the biggest difficulties that awaited road workers in the development and modernization of the E39 highway.
Songefjord is one of the most impressive places in Norway. It is the largest bay in Europe.
Computer shows a floating transport highway. Photo: YouTube.com
Dimensions of water obstacle:
✅ Length – 204 km
✅ Width – 1 km
✅ Depth – 1308 m
Planning for the crossing began with a detailed study of the seabed, soil conditions, and geological conditions. The team included architects, civil engineers, and marine biologists. Surveyors, weather forecasters, and ecologists also participated.
They studied the underwater currents in Songfjord, wind directions, wave intensity, bottom relief and many other parameters. The bridge was rejected. The underwater tunnel remained. But an unusual one.
Such a thing had never been built in the history of human civilization. Although, after thinking it over, historians of the industry found the British engineer Edward Reed. The naval architect had already proposed the idea of a floating tunnel across the English Channel in 1882. But, fearing a European attack on the island, the British rejected the proposal.
Divers take soil samples and other specimens from the bottom of the fjord. Photo: YouTube.com
Under pressure from circumstances, Norwegian experts came to the following decision: a floating structure is the only possible way to cross the Songefjord without a ferry.
Schematically and simplified, the device can be imagined as a pipe (tubing) passing between the banks of the bay in the water column. For ease of movement (it is proposed to be one-way), two parallel pipes will be laid. In places, they will be connected by technological transitions.
The term "floating" in relation to the tunnel is a relative term and can be misleading. The structure will be laid 20-30 meters below sea level. The tunnel will be connected to the bottom and held by anchors on cables, and pontoons will be on top. So the structure will be stationary and will not dangle in the bay. The design length of the transport line is 1,2 km. The engineers leave a distance of 400 m between the "fastening" points. This is enough to avoid interfering with shipping.
The ship moves between the pontoons of the submersible floating tunnel. Photo: YouTube.com
Technologically, the construction process will be divided into two parts: onshore and offshore. Concrete sections of the tunnel will be manufactured onshore. They will then be delivered to their destination by ferries and loaded by cranes to the required depth. Then the underwater operation begins – connecting the elements.
There is no reliable information about the completion date of this unique facility: 2035 or 2050 are mentioned. The developers cite a bunch of arguments in favor of the floating tunnel costing $25 billion. The main ones are: the structure does not spoil the view of the bay, is environmentally safe, does not create noise, and is not affected by storms. But little is said about the risks.
This is what the floating tunnel will look like schematically. Photo: YouTube.com
Whether cars will travel through the pipes is an open question. After all, where will the exhaust gases go in that case? Conventional ventilation systems for such closed spaces will not cope. Rather, cars will be transported by car carriers powered by electric traction.
What if there is an explosion or fire in the pipe? What are the escape routes for passengers? Is there enough safety margin if a submarine or large fish hits the object? Will the trawl gear or anchor of a deep-draft vessel passing over the tunnel get caught?
There are many questions, and they are disturbing...
Road builders, driven by the rush of humanity, are coming up with new ways to reduce the distances between populated areas and industrial facilities. They figure out how to make travel comfortable and deliver cargo quickly. To do this, they smooth out terrain, build bridges, and bite into rock formations. The industry is rich in discoveries, innovations, and fantastic technologies. And here is a fresh example – the Scandinavians with their floating tunnel.
Prerequisites for the birth of the project
Norway – a prosperous, rich state with unique nature. Tourists come here to admire, among other things, the stunning fjords. Narrow sea bays cutting deep into the land are not only the country's heritage, but also an eternal problem. For road workers, first of all.

The international highway number E39 runs along the western coast of the country. The route connects Trondheim in Norway with Aalborg in Denmark. Its length is not the largest – 1330 km. In principle, it is possible to cover the route on the car in 10-11 hours is a task that any driver can handle. You can drive slowly, observing speed limits and making stops for a snack or to contemplate the same beauties.
In fact, the minimum a motorist can expect is 23 hours. The thing is that you need to cross 9 fjords by ferry. At the same time, law-abiding citizens will have to wait in line, follow the unwavering schedule of disciplined carriers, and spend extra money. These circumstances complicate the trip and irritate drivers.

Adding to the inconvenience are the two E39 road lanes, which are unwilling to accommodate the ever-increasing flow of cars. The Norwegian government, obliged to respond to challenges, has instructed the Public Roads Administration to sort out the situation. Especially since it is too expensive for the government to maintain an entire ferry fleet.
For example, in Hordaland, located south of Bergen, there are 5 ships transporting cars. But the queue does not dissipate. The work of the ferry crossings, let us remember, directly depends on the weather. And it is very unstable in the polar regions.
Norwegian road megaproject
Ten years ago, the said Department developed active activities. First: it is necessary to modernize the international highway, adding a couple more lanes. The usual duties for the Orange Vests. Modern technologies allow road repairs to be carried out on kilometer-long sections without stopping the traffic flow.

Second: where conditions allow, the banks of the fjords will be connected by bridges of various configurations. However, given the soil conditions and seismic activity of the region, bridges are not a panacea everywhere.
Thus, it is impossible to build a bridge between Stavanger and Bergen, the country's major cities. The strait is deep - more than 300 m. It was decided to build an underwater concrete tunnel here.
It is difficult to count similar cases in international construction practice. Such tunnels have been built successfully for a long time: from 30-meter pedestrian to 53-kilometer railway. Basically, they run along the bottom. There are few examples below this level: the Eurotunnel under the English Channel, the Japanese Seikan.

The length of the Norwegian tubular tunnel with a diameter of 10,5 m should be 27 km. The depth is 392 m, i.e. below the bottom. Three threads need to be laid: two for movement Transport in different directions and one service.
The contractor prepared the design documentation, received parliamentary approval in 2017, and received 1,73 billion euros in funding. The contractor, Rogfast, promised to start running cars through the underwater pipes by 2026. However, the first explosion of coastal rocks at the construction site in January 2018 blew both the technical and economic justifications of the project to pieces.

The reality turned out to be more complicated than it looked on paper and on the computer. To the credit of the Norwegians, they suspended construction, adjusted plans and started again in 2020. Now the budget has increased to 2,55 billion euros, and the commissioning dates have been pushed back to 2028.
However, these were not the biggest difficulties that awaited road workers in the development and modernization of the E39 highway.
Underwater floating submersible tunnel
Songefjord is one of the most impressive places in Norway. It is the largest bay in Europe.

Dimensions of water obstacle:
✅ Length – 204 km
✅ Width – 1 km
✅ Depth – 1308 m
Planning for the crossing began with a detailed study of the seabed, soil conditions, and geological conditions. The team included architects, civil engineers, and marine biologists. Surveyors, weather forecasters, and ecologists also participated.
They studied the underwater currents in Songfjord, wind directions, wave intensity, bottom relief and many other parameters. The bridge was rejected. The underwater tunnel remained. But an unusual one.
Construction of the building
Such a thing had never been built in the history of human civilization. Although, after thinking it over, historians of the industry found the British engineer Edward Reed. The naval architect had already proposed the idea of a floating tunnel across the English Channel in 1882. But, fearing a European attack on the island, the British rejected the proposal.

Under pressure from circumstances, Norwegian experts came to the following decision: a floating structure is the only possible way to cross the Songefjord without a ferry.
Schematically and simplified, the device can be imagined as a pipe (tubing) passing between the banks of the bay in the water column. For ease of movement (it is proposed to be one-way), two parallel pipes will be laid. In places, they will be connected by technological transitions.
The term "floating" in relation to the tunnel is a relative term and can be misleading. The structure will be laid 20-30 meters below sea level. The tunnel will be connected to the bottom and held by anchors on cables, and pontoons will be on top. So the structure will be stationary and will not dangle in the bay. The design length of the transport line is 1,2 km. The engineers leave a distance of 400 m between the "fastening" points. This is enough to avoid interfering with shipping.

Technologically, the construction process will be divided into two parts: onshore and offshore. Concrete sections of the tunnel will be manufactured onshore. They will then be delivered to their destination by ferries and loaded by cranes to the required depth. Then the underwater operation begins – connecting the elements.
Clarifying moments
There is no reliable information about the completion date of this unique facility: 2035 or 2050 are mentioned. The developers cite a bunch of arguments in favor of the floating tunnel costing $25 billion. The main ones are: the structure does not spoil the view of the bay, is environmentally safe, does not create noise, and is not affected by storms. But little is said about the risks.

Whether cars will travel through the pipes is an open question. After all, where will the exhaust gases go in that case? Conventional ventilation systems for such closed spaces will not cope. Rather, cars will be transported by car carriers powered by electric traction.
What if there is an explosion or fire in the pipe? What are the escape routes for passengers? Is there enough safety margin if a submarine or large fish hits the object? Will the trawl gear or anchor of a deep-draft vessel passing over the tunnel get caught?
There are many questions, and they are disturbing...
- Timofey
- youtube.com
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