| Case Name |
The steel tower collapsed during steel tower decommisioning operation. |
| Pictograph |
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| Date |
August 29, 1996 |
| Place |
The Kariya City, Aichi Prefecture. |
| Location |
Steel tower decommisioning operation field of the 250m height. |
| Overview |
For disassembly removal of the steel tower, the worker was doing the inclination modification work of the steel tower and height spare work of the bracing wire. Immediately after the completion of that work,the tower collapsed and workers close to the tower sufferred.
Due to the abnormality of the clamp for the bracing wire lead-in of the steel tower,this disaster was generated by the slip in the bracing wire. |
| Incident |
This operation was to remove an old steel tower(250m), using the jacking down method.Jacking down method is that Making jack frame to every main post , then cut the tower from bottom part by gass one by one.After the removal of the cut part, then make the upper part of the tower down by jack.
In this method, drawing and releasing the bracing wire, the inclination of tower is corrected.This removal work was done through 6 time's jacking down , the 40m of the tower was already removed.
The accident day, they were about to do the 7th jack down The correction of inclination and bracing wire were done simultaneous ly. Immediately after the information of the completion of correction of inclination and bracing wire, the tower tumbled down to south direction,and 4 workers working close to the tower sufferred. |
| Sequence |
The method used in this removal work was the new one. So the pre-survey to confirm the safety was insufficient. And how to stop the correction of bracing wire , how to escape from the sudden danger( the escape root) were not established.
And, the work was carried out without the manual how to prevent the tower from tumbling down by using clamp to fix the bracing wire. |
| Cause |
By the insufficiency of tightening the clamp volt or the attachment of north-side bracing wire of the most upper stage, the bracing wire slipped in the clamp. Then the tension of bracing wire was released ,and the tower tumbled down losing balance. |
| Response |
It was dismantled and was removed on the ground, since the steel tower collapsed. |
| Countermeasures |
The manual on safety ensuring of the work and clamp mitred joint which fixes the bracing wire must be made, and it is necessary that manual is known to everybody. |
| Knowledge Comment |
On assembling a new method, assessments have to be carried out to confirm the safety of work.Checking the safety per work, and according to the result, work manuals must be made.
And the manual must be informed and educated to every workers. |
| Background |
It was insufficient to carry out the assessment in adopting the new method. It was insufficient to carry out the prior examination for ensuring the safety of the work. The operating manual on clamp mitred joint which fixed bracing wire was not done. |
| Reason for Adding to DB |
Because collapse disaster in the decommisioning operation is frequent. |
| Scenario |
| Primary Scenario
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Insufficient Analysis or Research, Insufficient Prior Research, Poor Value Perception, Poor Safety Awareness, Organizational Problems, Inflexible Management Structure, Ignorance, Insufficient Knowledge, Non-Regular Movement, Movement During Transition, Non-Regular Operation, Emergency Operation, Regular Movement, Dangerous Movement, Planning and Design, Poor Planning, Bodily Harm, Death, Bodily Harm, Injury, Failure, Large-Scale Damage
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| Sources |
http://www.jaish.gr.jp/
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| Number of Deaths |
1 |
| Number of Injuries |
3 |
| Physical Damage |
The steel tower. |
| Field |
Civil Engineering
|
| Author |
OHDO, Katsutoshi (National Institute of Industrial Safety)
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