The Seongsu Bridge disaster was a deadly bridge collapse that occurred on the morning of October 21, 1994 in Seoul, South Korea. 32 people died and 17 were injured when a section of the upper truss of the Seongsu Bridge collapsed onto the Han River. A combination of faulty welding, rusted extension hinges, and insufficient maintenance resulted in the structural failure of the bridge.
The Seongsu Bridge opened in 1979 and was the 11th bridge constructed over the Han River, connecting the northern Seongdong District to the southern Gangnam District. The bridge became one of the busiest bridges in Seoul and was built as part of military dictator Park Chung Hee's plan to develop the region south of the Han River (known as Hangang).
Seventeen Seoul Metropolitan Government, Dongbu Corporation, and Dong Ah Construction officials were convicted in connection to the collapse. The Mayor of Seoul Lee Won-jong and his successor Woo Myoung-kyu both resigned in response to the disaster. On November 10, 2000, the Dong Ah Group, the parent company of Dong Ah Construction, filed for bankruptcy and the company dissolved on May 11, 2001. The collapse was part of a string of disasters during the modernization of South Korea, including a fire on board the Kukdong-ho sightseeing boat 1987, the sinking of MV Seohae, the crash of Asiana Airlines Flight 733 and the Gupo Station rail accident in 1993, and the Daegu gas explosions and Sampoong Department Store collapse in 1995.
Construction for the Seongsu Bridge began on April 9, 1977, and was completed on October 15, 1979, by the Dong Ah Construction Industrial Company at a cost of 11.58 billion won (equivalent to ₩83 billion in 2025). At the time, foreign firms were excluded from construction contracts, stretching thin domestic construction companies who faced increasing demand as a result of military dictator Park Chung Hee's development plan south of the Han River. The cantilever bridge had four lanes of traffic, a width of 19.4 metres (64 feet), and spanned 1,160 m (3,810 ft). The speed limit on the bridge was 60 km/h (37 mph). The bridge was praised for its focus on its aesthetics in addition to functional considerations, setting it apart from other bridges built at the time. The bridge became the 11th bridge constructed over the Han River and alleviated traffic on the nearby Yeongdong and Hannam bridges.
Two years earlier, the Second Haengju Bridge collapsed during construction with no casualties. Later that year, the Changseon Bridge (창선대교; 昌善大橋) in Namhae, South Gyeongsang Province, collapsed under similar circumstances as the Seongsu Bridge. At the time, bids for construction projects frequently went to companies that promised the fastest construction, incentivizing cheap and rushed construction at the expense of safety. Dong Ah Construction's bid for the Seongsu Bridge's construction contract was half the price of its expected cost at the time. The rushed construction of the bridge was attributed as a negative consequence of South Korea's ppalli ppalli (빨리빨리; lit. 'quickly, quickly') culture.
The Seongsu Bridge linked the Seongdong District north of the river to the southern Gangnam District and was one of the busiest bridges in Seoul. Following the development of the Gangnam region, the number of vehicles using the bridge increased exponentially to 160,000 vehicles per day. The bridge connected to the Seoul Olympic Highway to the south. During the 15 years from its construction to its collapse, the Seongsu Bridge had never been subject to a detailed inspection because it was less than 20 years old and inspections had focused solely on aging structures.
On October 20, 1994, at 9:30 p.m. KST the evening before the collapse, workers for the Seoul Metropolitan Government laid a small steel plate onto a seam on the bridge, 50 m (160 ft) away from the site of the eventual collapse, to cover up a large gap that had formed at the joint. Repairs for the bridge had been scheduled for that day but were postponed due to bad weather.
On Friday, October 21, at 6:00 a.m., drivers filed a report after seeing cracks in the bridge, but the city government dismissed the reports, saying that the crack had been repaired through the installation of the steel plate.
At 7:38 a.m., during the beginning of the morning rush hour, a 48-metre (157-foot) span on the north side of the Seongsu Bridge suddenly gave way into the Han River 20 m (66 ft) below. Survivors of the collapse compared the sound of the collapse to thunder. Traffic was flowing at a speed of 40 kilometers per hour (25 mph), and a total of six vehicles were involved in the incident, including a police van and a commuter bus carrying 31 occupants. The police van carried 11 police and auxiliary police officers who were selected as model officers for Police Day celebrations that day. Heavy rain the night before the collapse reportedly reduced the number of vehicles on the road at the time. The collapse sent two cars and the police van down with the bridge, while an additional two cars fell into the river. The Number 16 bus operated by the Hansung Transportation Company was traveling North from Seoul Grand Park to Beon-dong and had nearly crossed the span when the bridge collapsed. The collapse caused the rear of the bus to tilt over backwards and plummet onto its roof, crumpling to half its size.
Thirty-two people were killed in the disaster including 29 victims on the Number 16 bus, which held 31 people when it fell. Among the dead were the bus driver and nine students from the Muhak Girls' High School and the Muhak Girls' Middle School in the Haengdang neighborhood of Seongdong District. Two of the victims on the bus survived the fall, but died waiting for first responders. The victims were treated at six hospitals, including the National Police Hospital, while the 32 dead were enshrined at 15 hospitals throughout Seoul. Among the victims was Adele Aida, a 40-year-old undocumented immigrant from the Philippines who was traveling to a meeting of Filipinos in Korea. Initial reports incorrectly reported over 40 deaths after police reports mistakenly combined the list of the dead and the injured.
The 11 police and auxiliary officers in the police van that fell with the bridge became the first to respond to the disaster. The officers undressed and used their clothes to tie a rope, saving a total of 10 drowning people. First responders arrived more than 20 minutes after the collapse, and rescue operations began at 8:10 a.m. KST. The late response of the first responders drew public ire and was the result of call center employees mistaking emergency calls for prank calls. These rescue operations were carried out by 30 officers and members of the Seoul Metropolitan Police and the Han River Patrol (한강순찰대) and consisted of two helicopters, three barges and 10 yawls. At 9:40 a.m., 20 divers from the Sea Salvage & Rescue Unit of the Korean Navy arrived at the scene to recover bodies from the river.
In response to the collapse, a total of 1,500 people were mobilized from the Seoul Metropolitan Police Agency, the Korean Armed Forces, and the Seoul Metropolitan Fire Service. The rescue team included 150 underwater exploration special forces from the fire service. Rescue efforts were hampered by rain, tides, and heavy traffic.
Officials initially stated that they believed the collapse occurred as a result of long-term excessive load on the bridge, culminating in the fracture of a rusted connection hinge. Vehicles carrying loads greater than their maximum capacity were regularly passing through the bridge. This led to a crackdown on overloaded vehicles over the Hangang Bridge out of fear of a similar collapse. A KBS News investigation the following day found that the Seongsu Bridge, along with the Dongho Bridge and the Hangang Bridge, suffered from rushed construction. In their report, KBS News noted that severely rusted steel on the bridges had been painted over, bolts were missing from the bridges, and segments of the bridges were only welded on the outside. Following the collapse, it was also revealed that the Seoul Metropolitan Government had planned to expand the bridge from four to five lanes through a reversible lane.