DL E&C announced on the 8th that it has completed the final caisson installation work at Ulleung Airport. With all 30 caissons installed about three years after the first caisson was installed in May 2022, the groundwork for the airport runway has been finished.
A caisson is a large concrete structure used for harbor embankments or breakwaters that is sunk into the sea.
Ulleung Airport is the first airport built on an island without road access in the country. There is no flat land for a 1,200-meter long runway on Ulleungdo, so it will be created by filling in the sea. DL E&C applied the "caisson method," which uses caissons to block seawater and fill the inside, for the airport construction, marking the first use in the country. The largest caisson installed at a depth of about 30 meters at Ulleungdo measures 28 meters high, 32 meters wide, and 38 meters long. This is the largest scale in the country, with a maximum weight of 16,400 tons.
Considering that the site for the airport is Ulleungdo, DL E&C applied a "wave-dissipating caisson" modeled after a beehive structure. The lattice structure of the wave-dissipating caisson creates spaces that dissipate the impact of waves. Additionally, DL E&C designed the caisson in a curved shape to further enhance resistance to waves. This allows it to withstand wave heights occurring once every 200 years (22.6 meters).
DL E&C manufactured the large caissons at Yeongilman in Pohang and transported them by sea. The caissons were moved to the dock using the Individual Pushing Caisson Carrier Vehicle (IPCCV). The IPCCV is equipped with hydraulic jacks that run along a rail laid on the ground, allowing it to move like a conveyor belt. Subsequently, the caisson was transported by tugboat. The marine transport distance was about 210 km, with a total movement distance of approximately 6,300 km.
After moving the caissons to their designated positions, they were permanently installed underwater. To support the total weight of 16,400 tons, 60,000 tons of gravel (small stones) were poured to establish a foundation. At that time, since the size and shape of the stones varied, divers manually filled the gaps between the stones to complete the setup.
A DL E&C representative noted, "Since Ulleung Airport is being built in the middle of the East Sea, where the waves are strong, high levels of technology and stability are required," adding, "All employees will do their best with a united effort until completion."
Ulleung Airport will be constructed in the area of Sado Port in Ulleung County, covering an area of 430,455 square meters (approximately 130,000 pyeong). DL E&C has secured the contract for 607.3 billion won under a turnkey method where they oversee design, material procurement, and construction. Construction began in July 2020, and the current progress is at 61%. The airport is expected to open in 2028 after completing landfill and runway construction for the main airport facilities. Once Ulleung Airport opens, travel time from Seoul to Ulleungdo will be reduced from the current 7 hours to about 1 hour.