[Infrastructure, From Construction to Replacement]④ "Retaining Walls Collapse, 60-Ton Rocks Crash"... The Outcry of Roads and Disaster Networks Built to 'Past Standards'

Extreme Rainfall of 100mm Per Hour and Prolonged Heatwaves Becoming the Norm

Landslide Restoration Costs Surge 11-Fold in 10 Years

Extreme Precipitation Exposes Infrastructure to 'Scouring' Phenomenon

"Improve Infrastructure by Alloca

Climate change is an increasingly powerful threat to the safety of infrastructure such as roads and water and sewage systems. With extreme rainfall of around 100 mm per hour and prolonged heatwaves becoming a part of daily life, the structural vulnerabilities of social overhead capital (SOC) facilities—including road slopes, retaining walls, and underground power grids—are being exposed one after another. There are concerns that the design standards for infrastructure safety are no longer keeping up with reality, as the climate conditions that were assumed at the time of design have completely changed.

According to the "Korea Climate Crisis Assessment Report" published by the Korea Meteorological Administration last year, the average ground temperature in Korea rose by 0.21 degrees per decade between 1912 and 2024. This increase is 16.7% faster than the previous rate of 0.18 degrees (based on the 1912–2017 assessment), mainly due to the more rapid warming observed in the most recent eight years. Nationwide, the average number of annual heatwave days from 2015 to 2024 stood at 15.6, a record high since the beginning of the meteorological observation. The extended rainy season of the past is now transitioning into shorter, more localized downpours of extreme rainfall. The average annual frequency of localized heavy rainfall events increased from 4.2 between 2015 and 2019 to 7.6 between 2020 and 2024. On July 17 last year alone, there were fifteen instances of 100-year-frequency torrential downpours, setting a record. Such climate changes highlight the vulnerabilities of aging infrastructure that was largely built between the 1970s and the 1990s and thus intensify disaster risks.

Limits of Road Slope Design Based on “50mm Per Hour”

The impacts of climate change are most quickly evident in mountainous areas and road slopes. According to the Korea Forest Service’s "Digital Slope Integrated Landslide Information System", last year landslides damaged 612 hectares, with KRW 185.5 billion required for restoration. Compared to the damage area (54 hectares) and restoration cost (KRW 16.9 billion) in 2016, each has increased by roughly elevenfold. Notably, while last year’s damage area was about half of that during 2020’s record-long rainy season (1,343 hectares), the number of deaths actually increased from 13 to 17. Experts attribute this to a shift in rainfall patterns: instead of widespread, prolonged rain, short bursts of extreme downpours in particular areas now translate even small collapses into casualties. The Ministry of the Interior and Safety reported that, among the 199 people killed or missing due to storm and flood disasters over the past decade (2016–2025), landslides accounted for 85 victims (42.7%)—the single largest cause.

Experts point out that many slopes and retaining walls nationwide were designed decades ago for maximum rainfalls of about 50 mm per hour, making them ill-equipped to withstand today's extreme downpours. According to the Korea Infrastructure Safety & Technology Corporation, spikes in indicators of extreme rainfall, such as the five-day maximum precipitation across the country, rapidly speed up water flow, exposing bridges to scour—the erosion of soil around bridge piers—leading to possible overturning or collapse. Similarly, retaining walls and cut slopes along roadways are vulnerable to catastrophic collapses and falling rocks as large volumes of rainwater infiltrate and rapidly erode ground support. In July 2023, heavy rain in Jinan-gun, North Jeolla Province weakened the ground, causing massive rocks and soil weighing up to 60 tons to cover a two-way road. Also, last July, when 61 mm of rain per hour fell in Osan, Gyeonggi Province, a 10-meter-high retaining wall for an elevated road collapsed.

On the 9th, when record-breaking heavy rain fell, a landslide occurred in the hills near Sillim Middle School in Gwanak-gu, Seoul, and officials are clearing the soil and trees spilled onto Sillim-ro while repairing the road. Photo by Hyunmin Kim kimhyun81@

The limitations of existing design standards are also being revealed in urban drainage facilities and underground infrastructure. According to a "National Assembly Probe Report on the Ohsong Underground Road Disaster", 426 mm of rain fell on Cheongju over three days from July 13–15, 2023, resulting in 34 casualties and property losses totaling more than KRW 75.5 billion. Urban drainage capacity proved wholly inadequate in the face of such deluges.

Particularly, the Ohsong Gungpyeong 2 Underpass, where most casualties occurred, had been classified by local authorities as "the safest road" prior to the tragedy because it had no history of flooding. The temporary levee that collapsed had been constructed based on the 100-year flood level (29.30 meters), but the actual flood reached an extreme level of 29.87 meters—higher than even the 200-year flood probability (29.33 meters)—and was thus quickly breached. This incident demonstrated that infrastructure designed for previous climate conditions can no longer be relied upon for safety in the face of extreme weather.

Even unseen underground power infrastructure is vulnerable to climate change. According to the Meteorological Power Index (PWI) of the Korea Meteorological Administration, summer peak demand pushes the index above 200 compared to a base of 100 for average annual power load. As the PWI quantifies changes in electricity demand due to weather conditions like temperature and humidity, a doubling of grid stress can lead to blackouts from transformer failures in apartment complexes or damage to insulation on underground city cables. Such overloading is also leading to more fires. National Fire Agency data shows that in the summer months (July–August) last year, there were 2,464 fires caused by electrical issues—a 12.4% increase from 2020 (2,192 cases).

‘Regional Infrastructure’ Even More Vulnerable... Construction Costs Alone at Least KRW 6.5 Trillion

Aging infrastructure is an even graver problem in rural areas. According to the "Special Bill Review Report on Facility Safety Reinforcement for Climate Change and Aging Response" from the National Assembly Land, Infrastructure and Transport Committee, out of 17,045 reservoirs responsible for disaster prevention in non-metropolitan agricultural and fishing communities, a staggering 96.8% (16,494) are facilities older than thirty years. Unsurprisingly, these are highly vulnerable to extreme rainfall.

Financial resources are the most essential requirement for climate adaptation. However, considering the strained budgets of local governments, it is difficult for them to implement facility upgrades with only their own financial capacity. According to the National Assembly Budget Office’s late 2025 estimate, at least KRW 6.4577 trillion will be required over the five years from 2027 to 2031 for climate response infrastructure such as the installation of 33,000 Internet of Things (IoT) sensors and 100 inspection drones in vulnerable facilities nationwide. Geun Yong Eom, Research Fellow at the Korea Institute of Construction Industry, said, “Maintenance and performance improvement costs for infrastructure older than thirty years are projected to reach KRW 118.2 trillion between 2026 and 2035, KRW 300 trillion between 2036 and 2045, and are expected to skyrocket to about KRW 52 trillion a year by 2050.”

The government also acknowledges the limits in responding to rapid climate change. To cope with extreme floods, it is set to recalculate the possible maximum precipitation (PMP) of dam basins based on the latest climate change scenarios. In addition, the number of artificial intelligence (AI)-based flood forecasting stations will be increased by 270 nationwide by 2030, and AI-powered CCTV for national rivers will be massively expanded.

Researcher Eom advised, “There needs to be a minimum funding rule to accumulate at least 1% of construction costs as a performance improvement reserve every year, so that we can prepare for the future needs for upgrades of aging infrastructure.”

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