| Case Name |
The excavator (crane) falling accident |
| Pictograph |
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| Date |
August 2000 |
| Place |
Okinawa Prefecture |
| Location |
The monorail substructure construction field |
| Overview |
It occurred in `the Okinawa city monorail substructure construction'. The construction was done on national road NO.58 wayside in Naha city. While the earth-auger mounting style rafter crane (25t) was circling to change the direction of the boom, it overturned on the side of National road NO.58. In this falling accident, two cars of the general public were crushed by the boom, and a driver was injured. |
| Incident |
The operator intended to turn to change the direction of the boom ( 17.5m) because he thought the crane was a obstacle to other works. The moment when he started to turn the crane, he had a feeling that the front side of the crane was floating. He lost a balance right after that, and the crane overturned on the side of national road NO.58. It crushed two cars of the general public. And the crane blocked all four downward lanes and one upward lane with the overturned boom. |
| Sequence |
1.He had extended the shortened outrigger before he started the operation to turn. But, he didn't extend it to the maximum though there was enough workspace.
2.He pulled up (about 1.0m) the leader, extending the boom and stopped it.
3.He turned the crane slowly, setting the angle of the boom to the side of the main body of the crane.
4.The moment when he started turning the crane, he had a feeling that the side of the crane was floating. And right after that, the crane lost balance and overturned. |
| Cause |
1.He didn't extend the outrigger to the maximal length though he could have extended it maximally. The operator thought he extended the outrigger to 3.7m. But, actually, it had been extended only to 3.2m.
2.The operator switched on the monitor for the prevention of overload to prevent the crane from overturning on the side of national road. But, he had put on the switch of the opposite side because the main body of the crane had not turned in the reverse direction.
3.He had neglected the safe confirmation of the situation, that the outrigger was overhanging and the outrigger reached the ground. |
| Response |
1.The owner took control of the accident situation by the founding of the emergency preparedness head quarters. The owner required a thorough safety management by notifying other construction sites of `the complete safety management' and holding the urgent safety council. In addition, the following were carried out: congruence patrol, the convention to prevent accidents using the monorail construction site.
2.The contractor who had caused the accident attempted to communicate the following matters completely to same kind works in the construction.
* They must grasp the type and the ability of construction equipment and make sure of the workplace where the construction equipment is used.
* The workers have to be posted to appropriate roles.
* They must confirm the system of workers' indicator.
* Every worker has to grasp his own work and confirm the work in the work meeting every morning.
* They have to reconfirm their work before starting the work. |
| Knowledge Comment |
1.They need to reconfirm the way to operate the construction equipment when they use the old-fashioned equipment.
2.If workers do their work asleep, an unexpected accident will happen. |
| Background |
1.Usually, it is the work that is done with the outrigger extended to sufficient length when they regulate a lane of national road 58 at the night.
2.This day was right after the Bon Festival holidays. So, the operator had been asleep.
3.The wind velocity at that time was 1.0 m/s, so it was no problem.
4.The operator had 19 years of experience in the field. And 12 years had passed since he acquired the driver license of the transport crane. |
| Sequel |
With cranes made after 1999, the computer detects the condition of all overhanging outriggers, and operators can confirm it in the panel display. |
| Incidental Discussion |
The crane rule #70 in those days determined `It is needed to exanimate the situation of the outrigger completely if the outrigger can't be extended to the maximum length.' |
| Account of Concerned Parties |
Before the operation, he went around the circumference of the rafter crane, checked the level condition of the main body of the crane on the driver seat, and started the engine. |
| Reason for Adding to DB |
1.It is important to alert the handling of the old-fashioned machine to the others.
2.It important to confirm the safety of crane works around construction sites. |
| Scenario |
| Primary Scenario
|
Carelessness, Insufficient Precaution, Poor Value Perception, Poor Safety Awareness, Misjudgment, Misperception, Usage, Operation/Use, Regular Movement, Dangerous Movement, Bodily Harm, Injury, Failure, Fracture/Damage, Damage to Society, Social Systems Failure
|
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| Number of Deaths |
0 |
| Number of Injuries |
1 |
| Physical Damage |
2 cars of the general public (they are third parties under passage). |
| Consequences |
The accident caused not only damages to human bodies and objects, but also caused the big tie-up around there because there were many commuters at that time. The influence on commuters and passengers of airplanes was very big. And this accident was greatly taken up in newspapers, etc. |
| Field |
Civil Engineering
|
| Author |
MIZOGUCHI, Hiroki (National Institute for Land and Infrastructure Management)
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