Hyundai E&C constructed 'Boryeong Undersea Tunnel' has been opened on December 1. The 6.9 kilometer long tunnel is the longest undersea tunnel in Korea and the 5th longest tunnel in the world.

The 2-lane unnel links links Daecheon Port in Boryeong-si, Chungnam to Wonsan-do, Ocheon-myeon, Taean-gun. It is 80m below sea level from Taean (upward line) to Boryeong direction (downbound line).

Hyundai E&C could use technologies, know-how and experience accumulated at civil works it did around the world. Korea benefited from Hyundai E&C's learning process at works in international projects.

To control the seawater inflow, Hyundai E&C applied the blasting NATM method in the seabed section, and optimized it through geological analysis using 3D computing. Hyundai E&C also used IMG (Intelligent Multi Grouting) method to minimize construction damage to surrounding facilities. This is a method that can block the inflow of seawater into the tunnel by precisely controlling the optimum pressure, flow rate, time, etc. of cement solution when constructing tunnel wall concrete.

In order to strengthen the durability of the Boryeong Submarine Tunnel, Hyundai E&C has strengthened the original wall thickness from 30cm to 40cm and the concrete strength from normal (24MPa) to high strength (40MPa).