“I’ve returned home for now, but I can't help but feel uneasy.”

This is what Mr. A, a nearby resident in his 40s, said on April 13 in front of a collapsed subway construction site for the Sinansan Line in Gwangmyeong, Gyeonggi Province. Nearby, there is an apartment complex with around 600 households. Mr. A and other residents were urgently evacuated to nearby schools and other facilities on the 11th, the day of the collapse, due to concerns over a potential secondary collapse.

Behind the barricade set up right next to the entrance of the apartment complex, the collapsed tunnel and road, along with the halted crane, hinted at the scale of the accident. Although all the apartment residents have returned home, they said they are still shaken and unable to calm their nerves. Ms. B, a resident in her 50s, said, “I don’t understand how a subway tunnel could collapse like that,” adding, “They say there’s no damage to the apartment, but everyone living here is feeling anxious.”

Local business owners are just as anxious. Around 40 small and mid-sized commercial buildings are clustered right in front of the collapsed area. One shop owner said, “I’m worried too, but my customers are also feeling uneasy,” adding, “I keep getting calls asking if the store is still open.”

The collapse occurred at around 3:13 p.m. on the 11th, when an underground tunnel under construction and the road above it gave way near Yangji Intersection in Iljik-dong, Gwangmyeong, at Section 5-2 of the Shinansan Line double-track railway project, being built by the Posco E&C consortium, Nextrain. Of the 19 workers on site at the time, two were trapped and went missing. About 13 hours after the accident, at 4:31 a.m. on the 12th, rescue authorities managed to save one of them.

The search for the other is ongoing. However, the rescue is expected to be difficult due to fears of further collapse and bad weather. The Gyeonggi Province Fire and Disaster Headquarters resumed the search operation later in the day, but internal search efforts could not proceed due to the risk of additional collapse. A fire department official said, “The site is filled with potential hazards,” adding, “We’ve confirmed that cracks have worsened due to the rain that started yesterday, and we cannot rule out the possibility of further subsidence.” The official also said, “The rescue operation is expected to take a considerable amount of time.”

The risk of an accident was detected at around 9:50 p.m. on April 10, 17 hours before the tunnel collapsed. Workers were evacuated from the site around 0:30 a.m. on the 11th, about two hours later. Police immediately closed the surrounding roads, but the collapse occurred while work was being done to reinforce the tunnel.

The police are currently conducting witness interviews with some of the workers who were involved in the reinforcement work and safety inspection of the tunnel at the time of the collapse. A police official said, “We have not yet investigated in detail what specific tasks the workers were performing on site during the reinforcement work.”