Seoul to bore tunnel under Han River linking Umyeon and Yongsan

The Seoul Metropolitan Government announced Thursday that it is seeking public input ahead of the planned Umyeon–Yongsan underground road, a 5.4-kilometer tunnel connecting Seocho-gu's Seocho-dong, near the northern exit of the Umyeonsan Tunnel, to Yongsan-gu's Dongbinggo-dong — running between 28-2 Banpo-daero in Seocho-gu and 66 Noksapyeong-daero in Yongsan-gu.

The city will hold a public review of the draft strategic environmental impact assessment for the private-investment project through Aug. 5, and will host resident briefing sessions on July 23 and 24.

A strategic environmental impact assessment analyzes the effects of a policy or plan on the natural environment, living conditions, and social and economic surroundings before the project moves forward.

In the draft assessment, the city said the tunnel aims "to ease traffic congestion on Banpo-daero and improve the inefficient mix of long- and short-distance traffic by building an underground road beneath Banpo-daero, thereby enhancing traffic convenience and safety for local residents and establishing measures to handle future increases in traffic volume on the road."

The city added that it expects the tunnel to relieve traffic on the existing surface road. It plans to reduce above-ground lanes from eight to 10 down to six to eight, create green spaces on both sides and expand pedestrian areas as part of surface improvement works.

Under the Environmental Impact Assessment Act, the head of an administrative agency drawing up a development master plan must publicly announce and display a draft strategic environmental impact assessment and hold a briefing session to gather residents' opinions.

The resident briefings will be held at 4 p.m. on July 23 at the Seobinggo-dong Community Center in Yongsan-gu, and on July 24 at the Banpo 2-dong Community Center in Seocho-gu.

Residents who wish to submit opinions after the review period and briefings may do so through Aug. 12. The results of the public consultation and whether feedback has been incorporated will be made public in November.

The Umyeon–Yongsan underground road is designed to ease chronic congestion on Banpo-daero and restructure a surface road where long- and short-distance traffic currently intermingle. The estimated project cost is 782 billion won ($518 million).

Construction is targeted to begin in 2029, with completion set for 2033. Surface improvement works above the tunnel are planned for 2034 to 2035, after the underground road opens.

Once complete, the Umyeon–Yongsan tunnel will join the under-construction Yangjae–Goyang expressway and the Metropolitan Area Second Beltway as tunnels carrying vehicle traffic beneath the Han River.