| Case Name |
The overturn of the transportable crane which happened in lift work in construction |
| Pictograph |
|
| Date |
July 10, 1997 |
| Place |
Niigata Prefecture |
| Location |
The construction field of the incinerator plant |
| Overview |
This disaster was the fall of the transportable crane in the refuse incinerator plant in the construction field. When it was intended to move the load by the method of what is called "sliding and drawing" which raises the jib while lowering the complementary roll, the outrigger float located in the rear (the suspension load side) of the crane subsided and slid horizontally on the overlay board. It dropped and more and more greatly subsided. It overturned. Damage to the jib etc was generated in the transportable crane. |
| Incident |
The overturn of the transportable crane by the subsidence of the outrigger in the ground |
| Sequence |
In order to lift the load far from the crane, the jib was expanded and the hook was rolled. However, the operator who judged that it was difficult to lift it by the big radius of operating intended to give the load access to the crane side. He intended to move it by the method of "sliding and drawing". However, the outrigger subsided, slid, dropped from the overlay board and sank in the ground because the horizontal load with sliding affected the outrigger which supported the vertical load. As the result, the crane overturned. |
| Cause |
The ground was weak in the cohesive soil. The size and rigidity of the overlay board which was used to disperse the load which affected the outrigger were insufficient. The unsuitable work by sliding and drawing was carried out. |
| Response |
To carry out the appropriate countermeasure such as laying a covering plate as a prevention of subsidence of outrigger |
| Countermeasures |
To decide work planning. To decide work method and to complete the publicity of it |
| Knowledge Comment |
To examine the work condition of transportable crane including the ground condition by investigating beforehand |
| Background |
The strength and installation method of the site where the transportable crane was installed had not been examined beforehand. Since the horizontal load by sliding affected the outrigger which supported the vertical load, the apparent ground bearing capacity lowered. Therefore, the outrigger subsided because of the destruction of the supporting soil which the operator did not intend, and the transportable crane overturned. |
| Scenario |
| Primary Scenario
|
Insufficient Analysis or Research, Insufficient Environment Study, Planning and Design, Poor Planning, Usage, Operation/Use, Failure, Fracture/Damage
|
|
| Sources |
http://www.jaish.gr.jp ( Japan Advanced Information Center of Safety and Health )
|
| Number of Deaths |
0 |
| Number of Injuries |
0 |
| Physical Damage |
Damage of the jib etc was generated in the transportable crane. |
| Financial Cost |
Not clear |
| Economic Loss |
Not clear |
| Consequences |
Many overturns of transportable cranes have occurred. It is an important issue in occupational safety to prevent this disaster. |
| Multimedia Files |
Fig2.Movable crane fall accident
|
| Field |
Civil Engineering
|
| Author |
TAMATE, Satoshi (National Institute of Industrial Safety)
KUNISHIMA, Masahiko (The University of Tokyo)
|
