Stalled construction site left exposed as heavy rain triggers ground subsidence in Seoul

"I can't walk this way anymore."

On Monday morning, across from the Junghwa 2-dong community center in Jungnang-gu, Seoul, 87-year-old Kim Woo-geum was heading to catch a bus when she stopped, looked at the narrow sidewalk hemmed in by construction barriers and turned back. An elderly man in a wheelchair stepped down onto the road, while residents pulling hand carts crossed at the intersection to go around.

Part of the pedestrian walkway along the edge of the construction site suddenly sank on July 15. Police, responding to a report that "the ground subsidence looks dangerous," set up a cordon at the scene.

Jeong Bong-gi, who runs a hansik buffet restaurant across from the site, said he arrived for work at around 6 a.m. that day to find the soil had been completely washed away, leaving the second and third basement floors of the building fully exposed. "The area under the pavement looked like it was just floating in mid-air," he said. "I thought a small child could fall in, so I called the police right away."

The site is a residential building project that has been suspended since April 2024. Originally planned as youth housing, it was later converted to a general apartment complex before construction ground to a halt due to project financing difficulties and other funding problems. The property is now in foreclosure proceedings. Work had progressed through the underground structural and floor concrete stages before the site was abandoned for more than two years.

Officials from the Jungnang-gu district office and Seoul Metropolitan Government architectural safety advisers who conducted an emergency inspection concluded that the subsidence stemmed not from the heavy rain itself but from a drainage overflow: as water pooled inside the construction site was pumped out through existing pipes, the volume exceeded the pipes' capacity and washed away surrounding soil. Inspectors determined there was no risk of the structure collapsing. The district office poured concrete at the affected point and filled gaps in the retaining wall with coarse sand and sandbags as reinforcement.

The damaged section was repaired, but residents' anxiety did not easily subside. Their chief concern was that a building abandoned in the middle of the city for more than two years could see the same thing happen again.

Cho Hyo-muk, 66, who has run a business nearby for 20 years, said the road had felt like it was gradually sinking ever since construction began, but the subsidence became more noticeable after the recent rain. "Seeing residents walk along the narrow strip next to the road because the sidewalk is blocked makes me uneasy," he said.

Another resident, who asked not to be named, said, "Construction has been stopped for years — shouldn't the management have been that much stricter?"

According to the Korea Real Estate Board's fourth survey of stalled construction sites, Seoul had 22 buildings with suspended construction as of last year, up 10 from 12 in 2022. Four sites in Seoul alone had been frozen for more than 15 years, left as eyesores in the urban landscape. Nationwide, the number of stalled construction buildings rose about 26 percent over the same period, from 286 to 361. Most involve projects that stopped due to financing problems or legal disputes among stakeholders.

The concern is that these sites are exposing safety gaps during the summer rainy season, when heavy downpours are common. Most halted construction sites have little more than safety fencing in place, with routine management and preparation for rain-related damage remaining lax.

A third-phase remediation plan for long-abandoned stalled construction buildings published by the Seoul Metropolitan Government last year found that 10 of the 12 buildings where construction had been suspended for two years or more were subject to safety-measure orders.

Jung Jin-woo, a professor in the department of safety engineering at Seoul National University of Science and Technology, said local governments need to step in to protect public safety when building owners cannot manage their sites due to financial difficulties. "As the construction slowdown drives a nationwide increase in stalled buildings, local governments should proactively survey the situation during the monsoon season and strengthen safety inspections," he said.

The district office plans to continue conducting regular special inspections alongside outside expert advisers, given the prolonged construction halt. A district office official said, "There are no small number of construction sites that have been suspended for a long time due to funding problems, which limits what we can do, but we plan to keep carrying out repeated inspections with outside expert advisers."