| Case Name |
A buried telephone line was cut off by the backhoe. |
| Pictograph |
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| Date |
January 30, 2003 |
| Place |
1-32, Chiyori town, Kochi City (the national road No.32) |
| Location |
An underground multipurpose (electric wire, etc) duct construction field |
| Overview |
On the No.32 national road around 139k330 (ascent), the excavation of the main line and junction above the underground multipurpose (electric wire, etc) duct was carried out. Judging from the trial pit drawing, they recognized that the pipe was laid under the sidewalk, therefore they carried out the excavation monitored by NTT. Though the excavation was carried out at the scheduled depth (about H=800) of the upper main line, the buried object was not recognized. Therefore, NTT returned because NTT thought they would not dig any further.
Afterwards, the sediment of the side collapsed and they did the excavation again. Then the pawl of the bucket damaged the cable, since they dug deeper than the scheduled excavation depth. |
| Incident |
They judged there was no problem, because the drawing of the buried object did not always match the actual field. And they let NTT return, since they decided not to dig any further on that day. |
| Sequence |
The company had done its best to prevent the accident related with a buried object, but, in the actual construction field, they believed that there would be absolutely no accidents in their construction field, and they lacked the awareness of risks. In addition, even though they were prohibited to dig the ground without the NTT observer, this rule was not kept then. |
| Cause |
* They judged there was no problem, because they had dug to the scheduled depth.
* The trial pit investigation was unclear.
* They worked without making any preliminary discussion with the main contractor, when an unforeseen work arose. |
| Countermeasures |
* The pawl of the backhoe should be rounded.
* We should not do the same kind work without an observer.
* The communication with workers about the buried object is required. |
| Background |
* The work was carried out by a few staff because it was night work.
* They left the work to the cooperating company, since they had done the same work. |
| Scenario |
| Primary Scenario
|
Insufficient Analysis or Research, Insufficient Prior Research, Misjudgment, Misjudgment of Situation, Planning and Design, Poor Planning, Regular Movement, Careless Movement, Failure, Fracture/Damage, Loss to Organization, Social Loss
|
|
| Physical Damage |
A NTT telephone cable was cut off. |
| Field |
Civil Engineering
|
| Author |
WATANABE, Kuniomi (Japan Road Contractors Association)
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