The tunnel project in Korea is huge: it is the largest in South Korea’s history. The tunnel will provide a link between the mainland and the Geoje Islands. The motorway will be 8 km and the tunnel itself will be 3 km. It currently takes three hours to reach Busan, but, in 2010, once the project is complete, the same journey will take only 40 minutes. The main contractor is Deawoo. I work for Strukton/Mergor. It is a fun project that I feel good about.
The project has been running for awhile, and so far 15 of the 18 sections are in place. Most of the sections are 180m long and 24m wide. Sections 17 and 18 are a little wider, as these will connect with the entrance to the secondary abutment.
The tunnel opens onto cable-stayed bridges, which are also a work in progress. Together the tunnel and the cable-stayed bridges cost a tidy €1.3 billion. The costs will run up much higher though: not only are there two cable-stayed bridges in progress, but another is also needed on the other side of the tunnel. Work on that bridge has not yet started.
To get there, you have to fly from Schiphol to Seoul, then take the airport bus to Seoul Domestic Airport and then fly from there to Busan. In Busan you are taken to the compound in the Tongyeong area.
The tunnel sections are parked close to one of the largest shipyards inKorea, called Sungdoo. The tunnels are transported there by two pontoons: GK 1 & GK 2. Various winches are on board, including eight mooring winches for the mooring anchors. On each GK there are also two contractions which clasp the sections with an EPS system developed by Mergor/Strukton.
Using the contractions, the GK1 and GK2 direct the tunnel sections and lower them into the correct place. This operation was documented and broadcast on RTL7. (LINK!!)
The preparations are much more time-consuming than the operation itself. If there are no problems with the measuring points and measuring equipment and if the wind conditions and current are favourable, the operation can be completed in a day, that is as long as no rubber seals pop out between two of the sections, as this can cause leaks, making the tunnel unusable. If this happens, push and pull cylinders are used to pull the tunnel away from the other sections slightly and then put it back in place. Fortunately it does not happen very often, butitis always a risk.
Catch frames are also used, which are a kind of guard on the primary side of the tunnel, which then fitinto the catch of the tunnel sections already in place. All the winches, including the mooring winches, in this two-pontoon system can be operated remotely from the pontoons and are monitored using cameras.
When lowering the sections into place a remote ballast system is used which runs from a laptop. Six ballast tanks are set up in the tunnel, which are removed after the sections have been lowered into place and the green light has been given. This can clearly be seen in the photos attached.
It has been and still is a great project, not only for the people working here through TOS, but also for TOS as a company. That has certainly been the case for me and I will probably be here to see a couple more sections lowered into place. Enjoy reading and watching the story of this rather special, and huge, project.