First complex tunnel of Korea will be Isu-Gwacheon complex tunnel. It will be private investment project.

Seoul City Council's Safety Construction Commission ordered a plan to limit tolls. Council ordered road and rainwater storage and drainage facilities coexist in one tunnel. It make it first complex tunnel in Korea.  Isu-Gwacheon road 5.4 km. It will solve flooding problem in Sadang and Isu area. It will also solve traffic congestion on Dongjak-daero and Gwacheon-daero. It will have road tunnel and 3.8km rainwater drainage tunnel in parallel.

Estimated construction cost is KRW 465.3 billion.

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