What caused the Seosomun overpass accident? Demolition, 3 dead, 4 injured

On the afternoon of May 26, 2026, a collapse occurred at the demolition site of the Seosomun Overpass in the heart of downtown Seoul. The accident resulted in the deaths of three people, including the site manager, the supervision team leader, and an external structural expert, and injured three others, while also causing disruptions to the Gyeongui-Jungang Line and some KTX services.

 

While the exact cause of the accident is currently under investigation, the D-grade rating of the aging elevated roadway and structural abnormalities that occurred during the demolition process are emerging as key issues.

 

 

1. When did the Seosomun overpass accident occur?

 

The Seosomun Overpass collapse occurred around 2:32 PM on May 26, 2026, at a demolition site in the Migun-dong area of ​​Seodaemun-gu, Seoul. Part of the overpass structure being demolished at the time fell to the ground, injuring personnel at the site. Firefighters and police were dispatched to the scene immediately after the accident, and the surrounding area was cordoned off due to the risk of further collapse.

 

This accident is classified not merely as damage to road facilities, but as a serious accident that occurred during demolition work. In particular, the traffic impact was significant as the accident site was located in a key downtown area close to Seoul Station, Chungjeong-ro, Seodaemun, and City Hall. Since there is a railway section beneath the overpass, it also led to disruptions in train operations. Immediately after the accident, the Ministry of Labor ordered a work stoppage and established central and regional industrial accident response headquarters.

 

 

2. What are the casualties from the Seosomun overpass accident?

 

The confirmed casualties from this accident so far are three deaths and three injuries. The deceased are reported to be the construction company's site manager, the supervision team leader, and an external structural engineer. It is known that they were personnel deployed to the site prior to the accident to check for structural abnormalities, adding to the tragedy.

 

The injured are known to be men in their 30s, 40s, and 50s, and it has been reported that they include officials from the Seoul Metropolitan Government's Infrastructure Headquarters and employees of the Seodaemun-gu Community Center.

 

In particular, it was reported that the community center employee was not a construction worker but was struck by the accident while passing under the overpass. Initially, it was reported as two deaths and four injuries, but later, one of the injured died, so the death toll was finalized at three.

 

 

3. Why are Grade D and aging mentioned as causes of the accident?

The Seosomun Overpass is an aging structure completed in 1966. According to the Seoul Metropolitan Government, although the overpass has handled downtown traffic for 59 years since its completion, it received a Grade D rating in a detailed safety inspection. A Grade D rating indicates a condition where major structural components have defects requiring urgent repair and reinforcement, and where the restriction of use must be reviewed.

 

The Seoul Metropolitan Government explained that structural damage had occurred repeatedly, including concrete spalling from bridge piers in 2019, the collapse of the deck slab in 2021, and damage to beams in 2024. Consequently, the Seosomun Overpass was completely closed starting September 21, 2025, and demolition work began. In other words, this accident was not a case of a road in use suddenly collapsing, but rather an accident that occurred at a structure that was already being demolished due to aging and safety issues.

 

 

4. What problems occurred during the demolition process?

 

The exact cause of the accident is currently under investigation. However, it is reported that during the demolition work on the day before or the day of the accident, a step difference—specifically, a partial subsidence—was observed in the top plate or slab, and the collapse occurred while the cause was being identified and safety inspections were underway. The reference document also summarizes the sequence of events, stating that the accident occurred during safety inspections after a subsidence of approximately 2.9 cm was discovered.

 

This point is important due to the nature of demolition work. Demolition is not simply the task of removing a structure; it must be carried out while continuously calculating how the remaining structure withstands the load. In the case of aging structures, the load balance can change drastically the moment certain members are cut or removed.

 

In the current investigation, the key issues are expected to be the appropriateness of the demolition method, whether facilities to prevent overturning were maintained, on-site safety inspection procedures, and whether the response after the work stoppage was appropriate.

 

 

5. What is the impact of traffic control and train operations?

 

The collapse of the Seosomun overpass had a direct impact on downtown traffic and train operations. In the aftermath of the accident, power was cut off to the overhead lines between Seoul Station and Sinchon Station, and KTX operations were suspended between Seoul and Haengsin Station, while commuter train operations were suspended between Seoul and Suseok. Anticipating that restoration would take a considerable amount of time, Korail adjusted the operation of some trains starting with the first train on May 27.

 

In the case of KTX, the suspension or alteration of operations for approximately 120 trains caused disruptions to the morning commute and long-distance travel. Gyeongbu Line KTX services are operating primarily between Seoul and Busan Station, and between Yongsan and Mokpo/Yeosu EXPO Stations, while Gangneung and Jungang Line KTX schedules have been adjusted to focus on routes departing from Cheongnyangni. The Seoul Metropolitan Government also implemented adjustments to some bus routes and concentrated dispatching to reduce downtown traffic congestion. When traveling by car, it is necessary to avoid the Seosomun-ro area and check alternative routes such as Saemunan-ro, Sejong-daero, and Sajik-ro.

 

Lastly, we pray for the repose of the souls of those who tragically lost their lives while fulfilling their responsibilities at the scene, and extend our deepest condolences to the bereaved families and the injured.

 

 

 

 

FAQ

Q. Where did the Seosomun overpass accident occur?

A. It occurred at the Seosomun Overpass demolition site in Migun-dong, Seodaemun-gu, Seoul.

 

Q. How many people were injured in the Seosomun overpass accident?

A. As of now, 3 people have died and 3 have been injured.

 

Q. What was the cause of the accident on the Seosomun overpass?

A. The exact cause is under investigation, and the key issues are aging and structural abnormalities during the demolition process.

 

Q. Will this affect KTX operations as well?

A. Yes, the operation of the Seoul-Haengsin KTX and Seoul-Suseok commuter trains has been suspended or adjusted.

 

 

 

 

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