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 Gangnam).
Seventeen Seoul Metropolitan Government, Dongbu Corporation, and officials were convicted in connection to the collapse. The Mayor of Seoul and his successor 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 a sightseeing boat in 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.
Background
Construction for the Seongsu Bridge began on April 9, 1977, and was completed on October 15, 1979, by the at a cost of 11.58 billion won (equivalent to ₩ billion in ). 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 , and spanned . The speed limit on the bridge was . 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 () 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 () 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.
Collapse
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, 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.