[Infrastructure, From Construction to Replacement]① Rapidly Aging South Korean SOC... Warning Light for Safety Threats

Serious Defects in Facilities Like Bridges Surge 3.4 Times in Four Years
By 2044, Over 75% of Facilities Expected to Be Over 30 Years Old
Seoul Launches Comprehensive Inspection of Aging Sewer Pipes, the Main Cause of Ground Subsidence

Editor's NoteAs South Korea's national infrastructure rapidly ages, a red flag has been raised over 'safety.' Infrastructure that once symbolized economic growth—such as roads, bridges, and water and sewage pipelines—are now turning into potential hazards that threaten public safety. The proportion of major facilities, such as roads and bridges, that have been in use for over 30 years is expected to increase sharply over the next 20 years. Especially as climate crises and natural disasters occur more frequently, the vulnerabilities of aging infrastructure are becoming even more pronounced. Even with regular inspections, the probability of unexpected issues arising due to unforeseen variables can increase. For this reason, the demand for creating safe national infrastructure and urban environments is more urgent than ever. To protect people’s lives and property, systematic maintenance and proactive reinforcement of existing facilities are essential. With artificial intelligence (AI) technology proliferating rapidly and a new term of local government heads beginning, this is considered the optimal time to innovate management systems through building smart infrastructure.

On the 10th, Seoul city contractors were inspecting aging sewer pipelines located in Jongno-gu. They were monitoring the condition through a CCTV robot vehicle that moves inside the sewer and records video. Provided by Seoul City

#Since August 2025, the Seoul Metropolitan Government has been conducting a phased, comprehensive survey of sewer pipelines that are over 30 years old. This initiative began after a large sinkhole occurred in Myeongil-dong, Gangdong-gu in March of the same year, prompting the city to inspect aging sewer systems. The survey targets sections rated as D and E, which require repairs, based on the city’s self-developed 'Priority Maintenance Zone Map' that utilizes five major ground condition factors contributing to ground subsidence and six types of underground facility information. Out of the total 6,029 km of aging sewer pipelines in Seoul that are over 30 years old, 1,848 km—sections with a high probability of ground subsidence—are being prioritized for inspection over two years. As of July, roughly 11 months after the survey began, inspections have been completed on 909 km, and more than one-third, or 326 km, have been identified as needing maintenance.

The number of aging facilities—those built over 30 years ago—among key national infrastructure such as roads, tunnels, and dams continues to rise each year, increasing the probability of defects such as cracks. According to the Korea Infrastructure Safety and Technology Corporation as of the end of 2024, there are a total of 177,142 major facilities managed by the national and local governments as well as public institutions. These include bridges, tunnels, port facilities, dams, and buildings that are required by law to undergo regular inspections. Of these, 37,473 facilities, or 21.2% of the total, have been in use for 30 years or more. In particular, bridges that have been in service for over 30 years account for 25% of all bridges.

Although facilities are maintained after completion, the number of major defects—such as unexpected damage, cracks, and deterioration—has been rapidly increasing every year. Data from the Korea Infrastructure Safety and Technology Corporation shows that the number of major defects surged from 275 cases in 2020 to 935 cases in 2024, an increase of 3.4 times in just four years. The proportion of facilities in South Korea that have been in use for more than 30 years is projected to reach 49.9% by 2034 and 75.3% by 2044. This means that in 20 years, three out of every four public infrastructure facilities will be considered aged.

60% of Underground Sewer Pipelines Have Exceeded Their Lifespan 

Among aging infrastructure, the most urgent target for repair is the sewer system. Sewer pipelines are cited as a major cause of ground subsidence, commonly known as 'sinkholes.' Because they are buried underground in densely populated urban areas and invisible to the naked eye, they pose an even greater risk. An analysis by the Korea Infrastructure Safety and Technology Corporation of 1,577 ground subsidence incidents nationwide between 2018 and 2025 found that 46.2% (729 cases) were due to sewer pipe damage. According to the Ministry of Climate, Energy and Environment, as of 2023, 58.5% of South Korea’s total sewer pipelines—approximately 170,000 km—were installed before 2004. The typical lifespan of a sewer pipeline is 20 years, meaning that about 60% have already exceeded their designed service life. A Seoul city official commented, "Pipelines are not automatically replaced just because their service life has been exceeded; maintenance targets are determined through internal condition assessments."

Sinkhole occurrences due to sewer defects are more frequent during the rainy season. Looking at the frequency of ground subsidence, the summer months of June to August account for 48.4%—nearly half—of all cases. This is an overwhelming figure compared to spring (28%), autumn (13.9%), and winter (9.8%). Heavy rains and monsoons weaken the ground, and rainwater infiltrates damaged sewer sections, washing away soil and causing the ground surface to collapse. Just last month, a ground subsidence incident occurred on a road in Gyerim-dong, Dong-gu, Gwangju, with a sinkhole measuring 1.5 meters deep and 1 meter in diameter. In 2024, a fatal ground subsidence accident also occurred in Yeonhui-dong, Seodaemun-gu, Seoul, during a period of heavy summer rainfall in August.

The aging of sewer pipelines is even more pronounced in major cities outside the capital. In particular, Daegu had the highest proportion of sewer lines in use for 20 years or more at 74.0%. Gwangju (67.0%), Seoul (66.1%), and Daejeon (62.7%) also exceeded the national average. Water supply pipelines are facing similar issues. According to statistics from the Ministry of Climate, Energy and Environment, as of 2023, South Korea had a total of 246,125 km of water supply pipelines, with 38.2% (93,969 km) being over 21 years old.

Maintenance Costs for Aging Infrastructure to Soar... 25 Trillion Won by 2040

Many types of infrastructure, including roads, railways, ports, and reservoirs, are entering the stage of being over 30 years old. According to the Construction Industry Research Institute, as of 2023, 52.9% of South Korea’s roads had been in service for more than 30 years. In particular, 84.8% of general national highways have long surpassed the 30-year mark. Road maintenance costs rose from 2.4 trillion won in 2013 to 4.4 trillion won in 2023—an increase of nearly 80% over 10 years.

Experts say that proactive measures are needed not only to reduce maintenance costs for aging infrastructure but also to protect public safety. According to the Korea Institute of Construction Industry, infrastructure maintenance costs are expected to approach the national social overhead capital (SOC) budget.

Um Geun-yong, a research fellow at the Korea Institute of Construction Industry, stated, "As abnormal weather events increase and infrastructure aging accelerates, it is becoming increasingly necessary to improve infrastructure performance and strengthen safety investments to address public safety risks. By 2040, it is estimated that maintenance costs will reach the current SOC budget level of around 25 trillion won."

This content was produced with the assistance of AI translation services.