A combination of faulty welding, rusted extension hinges, and insufficient maintenance resulted in the structural failure of the bridge.

Seventeen Seoul Metropolitan Government, Dongbu Corporation, and Dong Ah Construction [ko] officials were convicted in connection to the collapse.

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,[1] 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.

[24][25] Traffic was flowing at a speed of 40 km/h (25 mph), and a total of six vehicles were involved in the incident, including a police van and a commuter bus carrying 31 occupants.

[24] The Number 16 bus operated by the Hansung Transportation Company [ko] was traveling North from Seoul Grand Park to Beon-dong and had nearly crossed the span when the bridge collapsed.

[22][18] 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.

[33] At 9:40 a.m., 20 divers from the Sea Salvage & Rescue Unit [ko] of the Korean Navy arrived at the scene to recover bodies from the river.

[10] 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.

[40] Radiographic testing carried out following the collapse found that 110 out of the 111 connections in the bridge were filled with defects and that welds often only penetrated 2 to 8mm when the beams were 18mm thick.

[41] The white paper further notes that had the Seoul Metropolitan Government and the Dongbu Corporation properly inspected the bridge and carried out basic repairs, the collapse would have been unlikely to occur.

[15] The original white paper was criticized for publishing the names, genders, resident registration numbers, addresses, and occupations of the victims, omitting only the personal information of the minors and eleven police officers.

[49] Four days later, prosecutors found damage reports submitted in February and April to the Seoul Metropolitan Government by the Dongbu Corporation, which was responsible for bridge maintenance and repair.

[55] Prosecutors decided against arresting former mayor of Seoul Lee Won-jong [ko], stating that they did not find evidence that he was ever informed of the imminent collapse.

[54][56] The 17 defendants were tried collectively at the 7th Seoul Criminal District Court under Judge Kim Dong-hwan (김동환), and proceedings began on December 15, 1994.

[57][55] Defendants from Dong Ah Construction were charged with criminal negligence resulting in death, injury, the obstruction of traffic, and an automobile accident.

[58] Defendants from Dong Ah Construction argued that the five-year statute of limitations for negligent manslaughter had passed because the bridge had been built 15 years ago.

In particular, the former head of the city's road construction office Lee Shin-young (이신영; 李臣永) was the only defendant not convicted with negligent manslaughter.

[68][51][69] Kim held a meeting with his cabinet on October 23 calling for the elimination of deficient companies from the construction industry and the revision of laws to increase the depth and breadth of inspections.

[70] In his address, he stated that the rapid development of South Korea since the 1960s had brought both positive and negative outcomes, and that his government would promise to minimize all risks to Koreans.

He then apologized, stating that the disaster was the result of his own lack of virtue and that he recognized the issues in the management system brought to light by the collapse.

[73] In response to the bridge disaster, opposition parties in the National Assembly called on members of Kim's cabinet to resign, raising motions of no confidence which were voted down.

In addition, the Cabinet paid for the medical expenses of the injured and compensated them in consultation with their families, with the exception of the police officers.

[74][25] The Temporary Workers Friendly Association of Korea (비근로자 한·비친선협) and the Lotte Welfare Foundation also provided compensation to the family of Adele Aida through the Philippine embassy.

[74] As a result of these investigations, the Dangsan Railway Bridge was closed for reconstruction on December 31, 1996, being re-opened to the public on November 22, 1999.

[47] On January 5, 1995, in response to the disaster, the Special Act on the Safety Management of Structures was passed, which expanded the frequency and scope of inspections.

[76][77][78] In July of that year, the Disaster Control Act would be passed, a response to the deadly collapses of the Seongsu Bridge and the Sampoong Department Store.

[8] The memorial is located in the middle of Gangbyeon Expressway on the north side of the bridge, and has been criticized for its inaccessibility by foot.