Korea Economy write for 'Daesim Rainwater Drainage Tunnel' first stage is starting with tender in June.  Construction start in November and completion in December 2027. Estimated price for Gangnam, Gwanghwamun, and Dorimcheon tunnels is 900 billion won.

Seoul Metropolitan Government put into implementation a 4 billion won 'Daejim Rain Water Drainage Tunnel' in flood areas in the city, in Gangnam Station, Gwanghwamun, and Dorimcheonplan.In November a plan was ordered. Local government will review it until May.

For example Gangnam Station is 10 meters underground and flooded always in heavy rain. For this station 3.1 km long tunnel will carry Gangnam water to Han river. Another 3.2  km tunnel for Gwanghwamun. And another 5.2km tunnel between Hyoja -dong and Cheonggyecheon.

plans to order a turnkey (design and construction bid) in June after reviewing the basic plan.

One obstacle is possible resident resistance to tunnel construction. Maybe also because of sinkholes near tunnel construction sites in past.

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