A section of the Seosomun overpass in Seoul collapsed on Tuesday after workers detected structural instability during demolition efforts [1].
The incident raises critical questions about the timing of emergency evacuations and the effectiveness of safety protocols when structural warnings are detected in dense urban environments.
According to the Seoul City Urban Infrastructure Bureau, the incident began during slab-cutting operations. Between 1:30 am and 2:30 am, the concrete slab sank by approximately 2.9 cm [1]. Choi Jin-uk, the head of the civil engineering department at the Seoul City Urban Infrastructure Bureau, said the slab-cutting work was conducted during those early morning hours [1].
Warning signs were first detected around 2:30 am [1], [2]. Despite the detection of these anomalies and a subsequent work stoppage, the structure remained standing for several hours. The overpass eventually collapsed around 2:30 pm, approximately 12 hours after the initial warning was identified [1].
Investigators determined that the collapse was caused by the failure of a supporting girder, known as a 'geodeu,' in the middle of the slab [1], [2]. This failure caused the slab to settle, ultimately leading to the total collapse of the section.
Reports indicate that the signs of collapse had already appeared while the slab-cutting process was underway [2]. The delay between the first detection of the 2.9 cm sinkage and the final collapse suggests a window of time where the structure was compromised but not yet fully failed [1].
“The overpass eventually collapsed around 2:30 pm, approximately 12 hours after the initial warning was identified.”
The 12-hour gap between the detection of structural settling and the actual collapse indicates a failure in risk assessment. While work was stopped, the continued presence of a compromised structure over a public area suggests that the threshold for total site evacuation or immediate stabilization was not met, highlighting a potential gap in urban demolition safety standards.
