Seoul document mandated additional support structures

Safety guidelines for the dismantling of the Seosomun Overpass required additional support structures to be installed when necessary to prevent a collapse, according to Seoul Metropolitan Government documents reviewed Wednesday. The provision has come under scrutiny after a structure gave way at the demolition site in Seoul’s Seodaemun District, killing three workers. No supplemental supports had been installed before the accident.

The requirement appears in the Construction Specifications for the Seosomun Overpass Reconstruction and Performance Improvement Project, a set of technical guidelines drafted by the city government in March 2025. The document states that contractors should install braces, support columns or other safety structures when needed to prevent deformation, settlement or collapse during demolition and to protect nearby facilities from damage.

Prepared in accordance with the Occupational Safety and Health Act, the specifications serve as the project's official construction guidelines and are intended to govern how the work is carried out.

City officials said engineers determined that additional supports were unnecessary under the approved design. “The girders were securely supported on both sides by the bridge bearings, so temporary bents or other auxiliary support structures were not required,” an official at the Seoul Metropolitan Government’s Urban Infrastructure Headquarters said. “The project was designed on that basis, and construction proceeded accordingly before the unexpected accident occurred.”

Police have stepped up their investigation into the collapse and are reviewing project records submitted by city authorities. The Seoul Metropolitan Police Agency’s Metropolitan Investigation Unit obtained demolition-related documents from the Urban Infrastructure Headquarters’ civil engineering division on Monday, the day of the accident. The materials included the site’s safety management plan and procurement contract.

Officials said the safety plan contains operational procedures and safety protocols governing the demolition work. Investigators also conducted a detailed forensic examination of the site between midnight and 4 a.m. Tuesday in cooperation with the National Forensic Service and the Korea Occupational Safety and Health Agency.

Police said they will determine whether the safety procedures outlined in the project documents were fully implemented at the site and whether demolition work was carried out in accordance with the approved plan.


권구용 9dragon@donga.com