Undersea Tunnel to Jeju-do

Jeju-do Undersea Tunnel

A snowstorm paralyzed Jeju-do’s air traffic for two consecutive days and ten thousands of visitors were stranded on the island. This issue proved to me once again that Korea has to built a rail connection from the mainland to the island. Sadly, the Jeju-do undersea tunnel project receives little attention and there are many doubts about the feasibility. This article is going to introduce this huge rail project and discuss the most important points.


The Problem and THE Solution

A week ago Jeju-do experienced the strongest snow fall in 32 years. 1,200 flights were cancelled and around 89,000 visitors were stuck on the island. Air traffic was halted from Saturday 5:50 pm to Monday 2:30 pm. A trains is more resilient to extreme weather. The KTX has no problems with snow or strong wind. Trains would maybe operate at a lower speed and cause some delay but there wouldn’t be any cancellations.

After flights resumed, it took another two days to transport all people from the island despite a higher frequency of flights. A train can transport more people than an airplane. A second airport will be constructed on the island but it won’t change much. Once a big storm happens, flight services and ship transport will be interrupted. In the future we can expect an increase in severe weather phenomena due to climate change. It won’t be the last strong snowstorm for Jeju-do.

But the main arguments for an undersea tunnel to Jeju-do aren’t the limited capacity of air flights and the vulnerability to extreme weather events. Seoul-Jeju is the busiest air route in the world. Over 10 million passengers fly on this route every year. The negative impact on the environment is huge. The introduction of the KTX from Seoul to Busan in 2004 reduced flights between these two cities immensely. A rail connection to Jeju-do would reduce the amount of flights. There would be several stops on the way from Seoul to Jeju-do. A train would be able to pick up more people and reduce the amount of flights from Gwangju to Jeju-do, too. Of course, such a large-scale infrastructure project has negative impacts on the environment but in the long-term it will reduce emissions by shifting from air to rail.


Jeju-do Undersea Tunnel

After the snowstorm the governor of Jeollanam-do and several news articles called attention to the importance of a KTX tunnel to Jeju-do. The Jeju-do undersea tunnel is not a new idea. In 2008 the first studies have been made to show how such a project will look like.

A high-speed train from Seoul to Gwangju takes only 92 minutes. The second phase (Gwangju-Mokpo) of the Honam Express Rail has to be completed in order to develop the rail connection to Jeju-do. In addition, a 66 km-long rail connection to the southern end of the mainland in Haenam has to be constructed. A bridge (28 km) to the island Bogil-do will lead to the beginning of the Jeju-do undersea tunnel. The tunnel won’t go directly to Jeju-do. The draft plan includes a detour via Chuji-do. The undersea tunnel would be 73 km long. Thus, it would be the longest underground rail tunnel in the world. Currently, the longest tunnel is the Seikan Tunnel (53.85 km) in Japan, followed by the Channel Tunnel (50.45 km) between England and France.

The following map shows the connection:

A KTX from Seoul to Jeju-do would take around 2h 30min. A flight takes 65 min but a flight requires you to check-in your luggage, get the boarding tickets, pass security controls, go to boarding 30 minutes before take off and then again pick-up your luggage.


How much would it cost?

That is, of course, the most important question. It is estimated that the Jeju-do undersea tunnel project costs somewhere between 14 to 20 trillion KRW (11 to 16 billion USD). According to a cost-benefit analysis by the Ministry of Land, Infrastructure and Transport (MOLIT) in 2012 the project isn’t feasible because it had cost-benefit ratio of 0.71-0.78 (costs are higher than benefits). However, if you include environmental aspects, then the result would be different in my opinion.

The project is still far from realization. We won’t see any progress on this topic in the near future. Maybe after the second airport on Jeju-do is completed, the government will consider to build a rail tunnel to Jeju-do. But a lot of uncertainty is linked to this project and maybe the tunnel will be never built.


Sources and Information: Namu Wiki | Wikipedia | The Jeju Weekly | News1

About This Author

Co-Author of Kojects. Interested in Sustainable Transportation, Urbanism and Korea.


You can post comments in this post.

  • What an exciting undertaking this would be. Do you know the reason for passing through Chuja-do? Does it make the length of the tunnel more feasible? Or is it more for residence/tourism perhaps?

    Philip Partington 2 years ago Reply

    • Yes, it would be a really exciting project if they realize it!
      I believe that the island could be some kind of emergency refuge in case of a fire. I don’t think that they would built a station on the island and that each train stops there.
      Probably the concept planners examined the seabed and they wanted to avoid too deep waters because of higher costs and more difficulties during the construction.

      Nikola 2 years ago Reply

  • Hey James down here in Daejeon, love your site! Anyway a very cool concept indeed but yeah the cost would be insane, and with all the earthquake scares recently (and the movie Tunnel) it is not help the case :) I think it would be better to continue it onward to Japan. Japan would be able to pick up a good part of the bill as well. This would drastically increase tourism on both ends too. Not to mention Korea is looking for a “creative economy” well a lot of engineers and even regular workers would be employed for what 10 years or more on this project? In today’s job market that is a hell of a lot of job security. I think it needs some fine tuning but it is possible. The only issue I see is that Japan at this time is more interested in completing the Shinkansen from Honshu to Hokkaido. That tunnel is already built, but as it stands it is only for regular trains not the Shinkansen (Hayabusa).

    James 1 year ago Reply

    • Dear James,

      that’s a great comment. I would love to see both! A tunnel to Jeju-do and a tunnel from Busan to Japan.

      Nikola 1 year ago Reply

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