The outdated Seosomun Overpass, built in 1966 and posing safety issues, will be demolished starting on the 17th of next month. A new overpass is scheduled for completion in February 2028. In the meantime, traffic congestion is expected during the 2 years and 6 months of construction when entering downtown Seoul.
The Seosomun Overpass connects Chungjeongno Station and City Hall Station on Line 2 of the subway. It consists of 18 piers and has a length of 335 meters and a width of 14.9 meters, accommodating 4 lanes of traffic in both directions. Currently, more than 40,000 vehicles pass through each day. Beneath the overpass, there is the Seosomun Intersection where the Gyeongui Line passes. It is also a railway track for KTX and regular trains traveling between Seoul Station, Yongsan Station, and the Suseo Rolling Stock Depot.
In this overpass, an accident occurred in 2019 when concrete fragments fell. Following a detailed safety inspection, it was rated as D level, which prohibited its use or required urgent repairs. In 2021, a section of the deck also fell, and last year, concrete beams fell and tension wires were damaged.
The Seoul city government has repaired the piers and lowered the weight limit for vehicles passing over the overpass from 30 tons to 10 tons. However, it judged that securing safety through repairs alone is difficult due to the overpass reaching the end of its lifespan, leading to a decision to demolish and reconstruct it.
According to the city of Seoul on the 29th, the demolition of the Seodaemun Overpass will take place in stages. Starting from midnight on August 17, one lane from City Hall toward Chungjeongno will be closed, and from midnight on August 24, one lane from Chungjeongno toward City Hall will also be closed. Then, at midnight on September 21, access to the overpass will be completely restricted, and demolition work will begin. The demolition is expected to be completed in May next year, 10 months later, after which construction on the new overpass will begin immediately. The target completion date is February 2028.
Once the Seosomun Overpass is demolished, the direction from Chungjeongno toward City Hall will reduce from a total of 4 lanes (overhead and ground) to 2 ground lanes, while the opposite direction will be reduced from 3 lanes to 1 ground lane.
As a result, traffic congestion is anticipated. The city of Seoul has requested that general vehicles detour through nearby roads such as Sajik-ro, Saemunan-ro, and Sejong-daero, if possible.
Of the 43 bus routes passing through Seosomun-ro, 20 express bus routes will detour starting from midnight on the 17th of next month. Eleven Incheon bus routes will turn around at Hongdae Entrance Station, and nine Gyeonggi bus routes are planned to detour via Tongil-ro, Sajik-ro, and Saemunan-ro. Some of the 23 city bus routes in Seoul are also scheduled to detour starting at midnight on September 21.
Oh Se-hoon, the mayor of Seoul, inspected the Seosomun Overpass site on the 28th and said, "Demolition is inevitable for the safety of citizens," adding, "We must work closely with relevant agencies to minimize traffic inconvenience during construction. All efforts should be made in this regard."