Seoul overpass collapse: Safety inspection proceeded despite 'subsidence risk'

Questions are emerging about the safety procedures followed during the demolition of Seoul's Seosomun overpass, which collapsed on May 26, 2026, resulting in three fatalities and three injuries. The overpass, built in 1966 and rated a 'D grade' in structural integrity, was undergoing demolition when a section unexpectedly crumbled.

Evidence suggests that warning signs were present before the fatal collapse. Earlier on the day of the incident, during slab cutting operations, a subsidence of approximately 2.9 centimeters was detected, leading to a work stoppage. Despite this indication of structural instability, a safety inspection involving experts proceeded shortly after, ultimately leading to the collapse.

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The dismantling should proceed in reverse order of construction, first removing slabs and then supports. During this process, there is a dangerous moment when the support alone must bear the load. Precautionary measures must be taken before cutting work, and we need to confirm if this sequence was followed.

Experts are scrutinizing the demolition process, emphasizing the importance of following established procedures, such as dismantling from the top down and ensuring adequate support during critical phases. There is concern that the sequence of operations may not have been strictly adhered to, potentially creating dangerous stress on the remaining structure. The fact that the inspection team entered a confined space beneath the slab, which was then supported only by a girder, is particularly being questioned.

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We need to investigate whether the pre-collapse subsidence measurement was done properly and if the work was carried out according to the safety management plan.

Furthermore, the decision to proceed with the safety inspection despite the earlier detected subsidence is raising concerns about risk assessment and protocol adherence. Experts suggest that a more thorough preliminary risk evaluation might have been necessary before allowing personnel into a compromised area. The incident occurred over a vital urban corridor, with roads and KTX train lines running beneath the overpass, narrowly avoiding a larger catastrophe.

Investigations have been launched by multiple agencies, including the Seoul Metropolitan Government, the Ministry of Employment and Labor, and the Ministry of Land, Infrastructure and Transport, to determine the exact cause of the collapse and assign responsibility. The focus is on uncovering whether procedural shortcuts were taken and if safety management plans were adequately implemented.

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Even to the naked eye, the supports looked weak, yet the experts entered. We need to clarify whether risk assessment or preliminary visual inspection procedures were omitted before entering the site.