| Case Name |
Collapse of the Korea Seoul Seongsu Bridge. |
| Pictograph |
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| Date |
October 21, 1994 |
| Place |
The Korea Seoul |
| Location |
Seongsu Bridge |
| Overview |
The central region of Seongsu Bridge over 48m in length which was built in Han River of the capital city Seoul city in Korea suddenly collapsed, while the bridge was in service. Bus and passenger car in use fell to the Han River about 20m below, since it was the commuting time in the early morning, and 32 persons died and 17 persons got injured. From the investigation after the accident, the actual condition of many "omission" became clear. |
| Incident |
At 07:40 on October 21 (Fri), 1994, 48m of the central region of Seongsu Bridge suddenly collapsed, which across Han River running Seoul the capital city of Korea, urban bus and 6 passenger cars that driving down the bridge fell in river about 20m below one after another. The fallen bridge girder which is upper part of pavement part did not sink in the underwater, since it was the dry season and the water depth was 3-5m, and urban bus and passenger cars which fell in the top wrecked and they became rolling big disaster. The victims were 17 day girls who on the bus and almost the other were workers driving to the office. |
| Sequence |
Seongsu Bridge is one part of arterial road the conects the Kanan district which is residential section in the southern in Seoul City and city center of Seoul City, and its has a lot of traffic volume, and the four lane roadway of 1160.8m length and 19.4m width is laid. Its construction work was started in April, 1977, and it was completed in October, 1979. The steel truss digit division where the accident occurred was the 672m length, and it was one of the suspension digits of the center part. Seongsu Bridge it was comparatively new that it went to the 17 bridges to which be built in Han River , and its traffic volume was over the double at the beginning, and standard rolling stock load were utilized at not 18 tons expected in the design but 24 tons. In addition, Seongsu Bridge complained that it had been trembling in motion, so the authorities in Seoul City also carried out the repair work of the emergency in the night in accident the previous day. It was said that the traffic jam arose, because especially, it was for commutation attending school hour in the accident-generation, and because the rain fell the rolling stock was crowded. |
| Cause |
(1) Bad welding of the suspension which member of the I-type cross section which was hanging the suspension digit of the center from the steel truss seems to be a main caus.
(2) There was visibility cuting corners between surface and splice plate of the fillet welding, so construction management and inspection method in the construction of Seongsu Bridge seemed to be remarkably slipshod.
(3) Calcium chloride, which was scattered in order to prevent the road surface freezing, chloride ingress was uppued for the cracks by poor weld or stress corrosion, and so that the corrosion of steel product might be promoted.
(4) There is a posshibility to produce unexpected partial cracks in the steel surface because in the cross-sectional shape of suspension steel product, the cone angle ( the relaxation curved surface ) for easing stress concentration was insufficient.
(5) Though there is no error at the content for the design, there was some possibility that the immature construction level wasn't sufficiently assumed.
(6) There were no technical standards on in-service maintenance repair of Seongsu Bridge.
(7) Because of the fiscal resource constraint ( budget ) of Seongsu Bridge while it was in service, the periodic check was not possible.
(8) There were no survey about the actual situation and the inspecting standard on the change ( increase ) of traffic load.
(9) There was no technology ( inspection ) standard on maintenance and welding of the bridge.
(10) There was no tender contract system which accurately selected the contractor.
(11) There was a social trend that however basic road of Seoul city facilities should be constructed quickly. |
| Response |
Seoul City was not the last to presume cause of accident was that traffic volume on the bridge increased, passage load became superfluous and the structure was damaged in the storage of the fatigue. On October 22nd, 1994, Seoul City released an interim report about cause of the accident that 1 inside of connection pin of 9 which connected collapsed suspension digit of the center with the fixing support digit of the steel truss broke, and other pins brake in a chain reaction by overload, and the suspension digit part in the center was separated and felt. The corrosion of this pin and the weld zone was also confirmed. And, investigation headquarters concerned police and prosecutor had grasped the abnormality of the weld zone of the bridge, since the August, 3 times, from the description of "the repair inspection diary" done the confiscation from Seoul east construction office. |
| Countermeasures |
At this opportunity accident of Seongsu Bridge , the Korea nation got angry and demand countermeasure to omission construction which spread in Korea.
It was decided that President Kim Young-sam ordered general checkup of national roads and bridges and appointed the foreign special enterprise on the Korea government for some main civil engineering works.
A consultant in the United Kingdam, Remdell Palmer oand Triton (RPT) Co. made successful bid the contract on integration and technical advice of the remedial work of Seongsu Bridge.
And, it was redesigned ( that existing concreate floor system is exchanged for the steel plate floor, etc. ) in order to suit the design load that removes and increased the suspension digit part in the center after the accident-generation of Seongsu Bridge for the inspection, in May, 1995, the modern construction received order at about 22 hundred million yen, and the construction began, and Seongsu Bridge was opened in July, 1997 again for service. |
| Knowledge Comment |
(1) Site welded work by hands should be often warns well it. Don't trust it as a principle.
(2) Penny wise and pound (human life) foolish. The infrastructure ( the social foundation facilities ) works in the back.
(3) The omission of the inspection is fatal.
(4) The civil engineering structure issues the signal, before breaks. Don't miss it.
(5) Slack off of civil engineer is end of all. |
| Background |
In the Seoul City, during the Korean War most part of bridges spanning the Han River were destroyed . In 1988, new high-rise apartment building area which center was the Seoul Orimpic Stadium had been swelling rapidly, so the volume of traffic in the city increase at a faster rate. Then enlargement demand of society for the bridge which spanning Han River and 2 bridges were carrying out construction in those accident days.
17 bridges have been built over the Han River, but in the investigation by the Korea society of Civil Engineers 1992, it says that the problem of the strain coming out in concrete degradation of the underwater concrete part of the bridge piers, in the bridge in 11out of the whole bridge, had been indicated. The Seoul City had planed a repair work for the total amount of 4 billion Won in 1995. |
| Sequel |
In Korea, the accident involving the collapse of a bridge occured after the 1970's 8 times.
A collapse of the bridge which is built in this inside in Han River of the Seoul City has occurred 3 times.
In Korea, the accident of Seongsu Bridge became the past maximum bridge accident.
There is just an accident in which construction, bridge piers of 10 and bridge girder part about 800m of the new fortune state Long Bridge recently collapsed in July, 1992.
In the accident investigation which made Seongsu Bridge which occurred for the stage in Korea this time frequently to be a beginning, the many people who make civil engineering technology ( engineering ) and bridge technology ( engineering ) a speciality participated. It is said that who left sense of crisis in the head of accident investigation and throw oneself into the breach were the elder people that studied and acquired civil engineering technology and bridge technology of Japan, even if there are various and historical history to it. It be have told that the energetic investigative action undermined the health and that the way of the some person died with the completion of the accident investigation report from overwork. |
| Incidental Discussion |
By self-confidence to 1990 ages in the part in our country Japan, the degree faced telling technology and myth of the absolute safety for the engineering had been faced such as Hanshin Earthquake, sodium leak nuclear fuel cycle Monju, JCO criticality incident, and overlapping H2 rocket launch failure. Afterwards, the following would be advocated : Technology and engineering based at last by extending twenty-first century which exceeded 2000 from the viewpoint of modesty attitudes such as failure science and sociotechnique. Decay falling of Seongsu Bridge was generated under usual common use condition. As that accident, many engineers of Japan used to commented that bridge in Japan was safely designed and strict quality control had been done. It was not a mistake, until Toki-Messed communication deck bridge in Niigata City, August, 2003 28 NISSIN lagoon Prefecture suddenly fell. |
| Scenario |
| Primary Scenario
|
Organizational Problems, Poor Management, Insufficient Analysis or Research, Insufficient Prior Research, Organizational Problems, Poor Staff, Insufficient Analysis or Research, Insufficient Prior Research, Misjudgment, Narrow Outlook, Non-Regular Action, Change, Bad Event, Mechanical Event, Bad Event, Chemical Phenomenon, Failure, Fracture/Damage, Failure, Fracture/Damage, Bodily Harm, Death, Bodily Harm, Injury, Damage to Society, Change in Perception
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| Sources |
http://japanese.chosun.com/photo/special/20040603/7.html
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| Number of Deaths |
32 |
| Number of Injuries |
17 |
| Physical Damage |
48m of the central region of Seongsu Bridge suddenly collapsed, fallen bridge girder upper part pavement part was not sinking in the underwater, urban bus and passenger car which fell in the top wrecked and they became rolling big disaster. |
| Consequences |
At this opportunity accident of Seongsu Bridge , the Korea nation got angry and demand countermeasure to omission construction which spread in Korea. |
| Field |
Civil Engineering
|
| Author |
KUNISHIMA, Masahiko (The University of Tokyo)
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