The Seosomun overpass in Seoul collapsed on Tuesday after crews detected structural warning signs during demolition work earlier that day [1].
The incident raises critical questions about the safety protocols used during urban demolition and whether the response to early warning signs was sufficient to prevent the failure.
According to Seoul city officials, the incident began during the early hours of the morning. Choi Jin-wook, head of the Seoul City Urban Infrastructure Headquarters Civil Engineering Department, said that slab cutting work took place between 1:30 a.m. and 2:30 a.m. [1]. During this window, workers observed that a concrete slab had sunk by approximately 2.9 cm [1].
This settlement served as a primary indicator of structural instability. The 2.9 cm drop suggested that the supporting girder, known as the 'geoder,' had broken [1]. This failure compromised the integrity of the overpass, creating a precarious situation for the site.
Despite the detection of these anomalies, the full collapse occurred around 2:30 p.m. [1]. This means the structure fell approximately 12 hours after the initial warning signs were recorded by the crew [1].
City officials and demolition crews had been monitoring the site, but the gap between the detection of the slab's descent and the eventual collapse suggests a rapid degradation of the remaining support systems. The overpass was already in the process of being dismantled when the girder failure triggered the final collapse [1].
“The overpass collapsed around 2:30 p.m., roughly 12 hours after warning signs were detected.”
The 12-hour window between the detection of a 2.9 cm slab settlement and the total collapse of the Seosomun overpass suggests that the structural failure of the girder was an immediate catalyst for instability. This incident may lead to a review of the 'safe' thresholds for slab movement during demolition and whether immediate evacuation or stabilization measures are required when such deviations are first measured.
