Highway Collapse Accident – Causes, Response (Korea Sejong Highway)

The Sejong Highway collapse accident has resulted in a devastating incident where the upper bridge deck collapsed, causing 10 casualties. As an engineer specializing in concrete structure analysis, I find this incident extremely unfortunate. As a structural engineer, I want to carefully analyze and address the details of this accident. This article summarizes the causes, investigation status, and countermeasures of the highway bridge deck collapse accident based on news reports. I hope this information is helpful.

Overview of the Sejong Highway Collapse Accident

On February 25, 2025, at 9:49 AM, a bridge deck structure collapsed at the construction site of the Cheongnyongcheon Bridge on Section 9 of the Seoul-Sejong Expressway, Cheonan-Anseong segment, located in Sanpyeong-ri, Seoun-myeon, Anseong-si, Gyeonggi Province. The accident resulted in 10 workers falling, with 4 fatalities and 6 injuries. It was confirmed that there was no on-site manager who directly witnessed the accident at the time. This is undoubtedly a tragic incident.

A Miraculous Survivor

A 62-year-old Chinese national worker, identified as Mr. A, miraculously survived the 30-meter fall along with the concrete deck, suffering only minor injuries. He reportedly told his family that “heaven helped him.” He is currently undergoing surgery and recovering from orbital fractures and other injuries. The relatively minor injuries he sustained may be attributed to the fact that he fell onto a slope covered with soil. However, as many other workers suffered severe injuries or lost their lives, a thorough investigation into the safety measures and structural issues at the time of the accident is necessary.

Three Possible Causes of the Sejong Highway Collapse

The exact cause of the Sejong Highway collapse is still under investigation, but CCTV footage and site inspections indicate that the girder (a structural beam supporting the bridge) shifted sideways and collapsed. Videos of the collapse are available on platforms like YouTube and Naver. After reviewing these reports and videos, I have summarized three possible causes below. However, the final cause will be confirmed only after the investigation is complete.

Load Distribution Issues During Girder Installation

   – The girder is a critical structural component that supports the bridge deck and carries vehicle loads. If the load distribution was not properly managed during installation, the girder might have lost balance, tilted, and ultimately collapsed.

Safety Issues During Launcher Movement

   – At the time of the accident, workers were moving a launcher (a heavy lifting device) backward on the girder. It is possible that the launcher exerted greater-than-expected loads, causing structural instability during movement. This may have led to the collapse due to an unexpected load imbalance.

Inadequate Safety Management

   – The previous two points address potential load imbalances and structural instability during construction. Safety management plays a critical role in ensuring that construction proceeds as designed. There are concerns that pre-checks to confirm alignment with design specifications may have been insufficient. Large-scale bridge construction projects should incorporate risk detection and preventive measures in advance. However, it is still unclear whether proper warning signs were detected and addressed before the collapse. If safety inspections or warning systems were inadequate, this incident highlights the need for stronger safety management measures.

Post-Accident Response

Police Investigation

The Gyeonggi Nambu Police Agency’s dedicated investigation team conducted a search and seizure operation on February 28, 2025, at 9:30 AM, targeting seven entities, including Hyundai Engineering, Korea Expressway Corporation, and Jangheon Industry among others. Investigators, along with labor ministry supervisors, are examining potential legal and technical violations in the construction process. The police are focusing on the work methods used during the accident and structural issues. They will review the collected materials to determine whether safety regulations were followed and assess the responsibility of the construction companies and contractors.

Government and Ministry of Land, Infrastructure, and Transport Response

The Ministry of Land, Infrastructure, and Transport (MOLIT) plans to establish a Construction Accident Investigation Committee (CAIC) to determine the causes and responsibilities of this accident. The investigation is expected to take approximately two months and will involve multiple experts to analyze:

   – Structural quality

   – Deformations due to temperature changes

   – The functioning of the launching truss equipment

Additionally, the MOLIT has suspended construction at three other sites using similar DR-girder or launching girder methods, including:

   – Sejong-Cheonan Expressway Osong Branch

   – Seosan-Asan Expressway DaeSan-Dangjin Section 2

   – Hamyang-Hapcheon Expressway Section 5

These projects will resume only after passing thorough safety inspections.

Emergency Inspection by the Ministry of Employment and Labor

The Ministry of Employment and Labor has announced industrial safety inspections for 22 construction sites managed by Hyundai Engineering, particularly in the road, railway, and excavation sectors. Furthermore, emergency safety inspections will be conducted at 349 high-risk bridge construction sites with spans exceeding 50 meters.

The Korea Occupational Safety and Health Agency will review construction drawings, compliance with design standards, lifting procedures for heavy equipment, and the conditions of machinery and tools. If violations are found, regional labor offices may issue suspension orders or impose regulatory measures.

The Ministry of Employment and Labor has stated that if Hyundai Engineering is found in violation of industrial safety laws, it will take legal action and impose strict penalties.

Future Measures and Prevention Strategies

This accident underscores the need for stronger safety regulations and enforcement in the construction industry. The following five key measures should be implemented:

Enhanced Safety Inspections at Construction Sites

   – The Korea Infrastructure Safety Corporation and related agencies should intensify safety checks at large-scale bridge and highway construction sites, particularly focusing on load distribution during girder installation and launcher movements.

Implementation of Real-Time Structural Safety Monitoring

   – Advanced smart construction technologies allow for real-time monitoring of structural deformations and stress levels. Adopting these systems can help prevent similar incidents.

Improved Worker Safety Training and Emergency Evacuation Protocols

   – Construction workers should receive comprehensive safety training and clear evacuation protocols to respond effectively to emergency situations.

Stronger Accountability for Contractors and Legal Regulations

   – Once responsibility for the Sejong Highway collapse is established, strict legal measures should be enforced against those responsible. Future regulations should be strengthened to ensure stricter compliance with safety standards.

Conclusion

The Sejong Highway collapse is a stark reminder of the critical importance of construction site safety. This incident should serve as a turning point for improving structural integrity and safety management in the construction industry. More information will be updated as the investigation progresses. I will continue to analyze the accident’s causes and share further findings as they become available.