| Case Name |
A dump truck braked sharply when going downhill and slipped, and turned over on its side. |
| Pictograph |
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| Date |
September 3, 2001 |
| Location |
In a site of gathering earth and sand. |
| Overview |
The 90t dump truck braked going downhill, then the tire was locked and the dump truck turned over on its side. |
| Incident |
In the runway for the dump truck, when a 90t dump truck loaded to capacity with earth and sand went downhill, control of the steering wheel was lost in a rut to the right, and the dump truck's rear wheel skidded. And the driver steered to the reverse and put the hydraulic brake (retarder) on the truck, then the tire was locked to stop, and it turned over on its side as the reaction. |
| Sequence |
In the work after the rain, when the 90t dump truck for transport of earth and sand loaded to capacity with earth and sand went downhill, control of the steering wheel was lost in a rut of the road. And the dump truck braked, then the tire was locked to stop, and it turned over on its side as the reaction. |
| Cause |
The runway had a width of 8m, which was narrow as a runway for the 90t dump truck, and also there were ruts in the runway.
The runway after a rain was easy to skid in.
The load was large when considering the condition of the road surface.
The runway repair had not been made.
The driver was so shaken that sudden steering and heavy braking action were done. |
| Countermeasures |
The width of the runway for the heavy dump is made to be more than 10m, and a dam (H=1.5m) is installed in the shoulder of a road.
Runway improvement is carried out by bulldozer or motorized grader.
Confirmation of the working condition is made through consultation with management supervisor, and the details of the work is decided.
If the abnormality ( unsafe position, etc. ) of the work environment was discovered, it is reported to the management supervisor immediately.
The questionnaire is put in the office, and the opinion of the operator is utilized for future work.
Each inspection (ATK) is done before the work, and it is reported to the each charge staff member. If there is an abnormal point, it is urgently dealt with.
KY activity of the each every group is made to be meaningful even though it takes much time. |
| Knowledge Comment |
With a large load piled in a dump truck, the center of gravity of the dump truck becomes unstable. In this condition, heavy braking and sudden steering are origins of the accident.
Runway for dump truck is made to have the enough width. The narrow way is damaged soon, because only the same place is passed again and again.
Even if there is the consciousness of the danger to the operator, without a field where opinion can be expressed such as KY activity, etc., the accident prevention countermeasure is not taken and the work is continued. In the result, accident arises.
It is necessary to investigate questionnaire and close call of the operator and to attempt the substantiality of inspection and KY activity each. |
| Background |
It was the situation in which they had to work even though the condition of the runway was that it was easy to slip in after rain.
There were no preparation and budget which ensured there was enough width of the runway needed.
There was no budget to repair the runway.
The cycle of work was busy, and there was no time to repair the runway by bulldozer or motorized grader.
The setup of the work depended on the operator. |
| Reason for Adding to DB |
There have been many sideslip accidents of dump trucks, and the causes are complicated and diverse. |
| Scenario |
| Primary Scenario
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Misjudgment, Misjudgment of Situation, Poor Concept, Poor Strategy or Concept, Poor Value Perception, Poor Safety Awareness, Organizational Problems, Poor Management, Usage, Operation/Use, Non-Regular Operation, Emergency Operation, Non-Regular Action, Emergency Action
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| Physical Damage |
A 90t dump truck. |
| Field |
Civil Engineering
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| Author |
IKAI, Seiji (ICHITEC CORPORATION)
BABA, Kanji (ICHITEC CORPORATION)
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