DYWIDAG Systems Stabilize one of the World’s Longest Immersed Tunnels

Geoje city is an important industrial city of South Korea and is located in the vicinity of Busan - location of one of the world’s largest container ports. : Geoje city is scattered on approximately 60 small islands and up to now, there has been no direct road connection between Busan and Geoje and commuters had to either use a ferry or put up with a 140km long detour to travel between the 2 cities.


The construction of an approximately 8.2km long highway from Busan to Geoje began in 2004. The Busan-Geoje Fixed Link will shorten the route to 60km and thus cut average travelling times by about two and a half hours. The new highway will not only relieve the surrounding roads and save logistics costs, but it will also strengthen the region’s economy.

The Busan-Geoje Fixed Link includes two stay cable bridges approximately 3.5km long as well as a 3.7km long immersed tunnel. Once completed, the tunnel will be one of the longest immersed tunnels in the world. With a depth of up to 50m, the tunnel is also the world’s deepest road tunnel. It is composed of 18 precast concrete tunnel elements that will be floated into position.

The first of the two stay cable bridges has two pylons, a main span of 475m and two side spans of 220m each. The second stay cable bridge leads over 3 pylons, with two main spans of 202m each and a total length of 672m. Due to the region’s high seismicity, the companies involved had to face special project requirements. Construction was also made difficult by weather conditions at sea: each section had to be stabilized to withstand possible storms.


DSI Korea was involved in several sections of the infrastructure project. The company supplied type 32 WR, St 950/1050 DYWIDAG THREADBAR® in lengths of 1.2m each for steel structure segment lifting. In additon, 4,640 anchor nuts and 160 anchor plates were delivered to the site. DSI Korea also supplied 312 type 36 WR, St 950/1050 DYWIDAG THREADBAR® in lengths of 2.96m each for stabilization. In addition, DSI Korea supplied a total of 312 hex nuts, 312 couplers and 624 lock nuts. Type 40 WR, St 950/1050 DYWIDAG THREADBAR® were used for the construction of the immersed tunnel. In addition, a total of 272 nuts and 544 couplers were supplied.

DSI Korea is pleased that DYWIDAG Systems were used for this special infrastructure project.


Yooshin Engineering Corporation, Seoul, Korea

Chungsuk Engineering, Seoul, Korea

Kumho ST, Seoul, Korea (connecting road); Taeah, Busan,Korea

Daewoo E & C, Seoul, Korea