Following a recent spate of accidents near excavation sites, including a large-scale sinkhole incident in Myeongil-dong, Gangdong-gu, Seoul, the government has decided to proactively inspect high-risk construction sites and disclose the locations of voids in the ground that cause sinkholes nationwide.

The Ministry of Land, Infrastructure and Transport (MOLIT) unveiled a safety management plan on May 27 that includes preemptive inspections of accident-prone areas as a series of large-scale sinkhole accidents in Myeongil-dong, Seoul, and Gwangmyeong, Gyeonggi Province, have recently occurred.

According to the ministry, the primary cause of recent sinkhole incidents is faulty excavation work. Of the 57 large-scale sinkholes (areas over 9 square meters and depths over 2 meters) reported between 2020 and 2023, 21, or 36.8 percent, were attributed to poorly conducted excavation work. While typical sinkholes are often caused by damaged water or sewage pipelines, serious incidents involving potential human casualties are mostly linked to construction defects in excavation projects.

Excavation work is also closely related to the formation of underground voids that lead to sinkholes. A special inspection of 94 excavation sites conducted between October and December last year revealed 68 underground voids.

This means that 0.191 voids were found per kilometer of excavation site inspected, which is significantly higher than the 0.115 voids per kilometer found during the regular inspection conducted last year. Of the 793 underground voids identified and reported to local governments by the Korea Authority of Land & Infrastructure Safety (KALIS) under the MOLIT from 2020 to 2024, only 393 (49.6 percent) had been repaired as of last month.

The MOLIT has decided to proactively manage risky areas such as excavation sites. Previously, ground safety inspections by the KALIS were conducted only upon request from local governments. However, a legal revision now allows the ministry to initiate inspections on its own authority.

The ministry will designate risk-prone areas based on several factors, including past subsidence history, underground water leakage volume, proximity to subway lines, and local geological conditions.

For example, in Seoul, 125 of the 226 large-scale construction sites (those with depths over 20 meters) that have a history of ground subsidence will be prioritized for inspection, particularly those near subway infrastructure and in geologically weak areas.

Beginning next month, the government’s underground survey data will be made public via the Underground Safety Information System (JIS) operated by the KALIS. In addition, to address the low repair rate of identified voids, which is currently below 50 percent, the ministry will publish statistics on the joint recovery rate by local governments.

However, if local governments, such as Seoul's autonomous districts, conduct their own geotechnical exploration and do not disclose the findings, the government plans to consult with them and encourage them to disclose the results in the JIS.

Kim Tae-byeong, Director of Technology and Safety Policy at the MOLIT, said, “By next year, we plan to improve the system so that the results of geotechnical explorations conducted by local governments and specialized organizations such as Seoul can be managed in the JIS. He added, “We are also working with the Ministry of the Interior and Safety to evaluate and score the joint recovery rate by local governments.”

The government will also strengthen pre- and post-construction safety measures. Currently, underground safety inspections are only mandatory for large-scale construction sites deeper than 20 meters. However, the new plan will expand this requirement to include smaller excavation sites. A new regulation will also impose fines on companies that fail to conduct the safety inspections properly.

Kim emphasized, “This plan is a first step toward fundamentally preventing large-scale ground subsidence accidents around excavation sites and establishing a more systematic underground safety management system.”