South Korea’s capital city Seoul has announced a W11.2t plan to build a 149km underground road network in the city.

The proposed road network will be located 40–60m below the ground and will have three north-south and three east-west underground tunnels.

Five out of the six tunnels will be divided into two 3m levels for smaller cars. One tunnel on the north-south route will have a single-storey tunnel for bigger vehicles.

The network will form a lattice pattern and the intersections will be connected to form two circular roads.

Subterranean car parks will be built at major downtown points and high-speed lifts will be created to link the underground roads with the surface.

The project is aimed at reducing traffic congestion on surface roads.

The network will allow travelling through the city in 30 minutes and will increase the average speed on surface roads from the current 24.2kmph to 32.6kmph.

The project includes disaster-prevention plans such as emergency shelters and exits every 250m for underground fires.

The first of the six roads, north-south route 3, is expected to be complete in 2017.

North-south routes 1 and 2 and east-west routes 1 and 2 are expected to be complete in 2019. The final plan for east-west route 3 has not been decided yet.

Work will start in 2010 with the design phase for north-south route 3.

The city hopes to get private capital to finance the project.