Korean bridge-tunnel links

21 October 2005

Mott Macdonald has been awarded two contracts as specialist adviser to supervising consultant Yooshin Engineering Corporation for the design and construction of US$2.8bn of new bridge and tunnel links to the mainland in South Korea.

One of the contracts relates to an 800m main span cable stayed bridge from Incheon Island in the north. The other is for construction supervision of a US$1.6bn fixed link between Busan on the mainland and the island of Geoje. The project consists of two cable stayed bridges with main spans of 475m and 230m, plus an immersed tube tunnel 3.7km long. The transition between the tunnel and the approaches to the bridges will be by means of an existing small island.

Client, GK Fixed Link Corporation, awarded the design and build contract to the Busan-Geoji Fixed Link Construction Consortium, who retained Daewoo Engineering and COWI for design services. The immersed tube units will contain twin tunnels for the carriageway and a service tunnel. Each precast unit will be 26.5m by 9.97m and accommodate 10.1m by 7.29m of carriageway T&TI was told.

The geology along the route is alluvium overlying andesites. The precast concrete tunnel units will be sunk into a dredged channel at seawater depths of up to 50m. Mott Macdonald said the tunnel will be one of the longest and deepest in the world and added that extensive ground improvement works would be required.

Early works actually got underway last year on the scheme, but major construction is yet to start. T&TI was told by Mott Macdonald that the precast yard was currently under construction and site accesses were being formed. The project is scheduled for completion in 2010.