| Case Name |
A crawler crane overturned when it rotated, hanging a mobile elevating work platform. |
| Pictograph |
|
| Date |
September 8, 1998 |
| Place |
Imajo town, Nanjo District, Fukui Prefecture. |
| Location |
The dam spillway pond. |
| Overview |
The mobile elevating work platform was lifted by a 80 ton crawler crane in the dam spillway pond, and during rotating, it overturned, and the boom hit a concrete wall of the pond, and it stopped. |
| Incident |
The slinging was done with 4 outriggers of the mobile elevating work platform which were held by 4 wire ropes, having a diameter of 12mm and a length of 6m, at each point. The wire ropes were new articles which had first been used the day before the accident.
The slinging person, after he confirmed that the mobile elevating work platform was off the ground, sent the signal to roll-up to the crane operator, and the roll-up started. The signal was communicated by the radio once, and the signal was not communicated afterwards.
After the roll-up started, the counter-clockwise turning was carried out afterwards.
Because the over-load cutout device operated, the 20m roll-up was done as the boom was raised.
Afterwards, the counter-clockwise turning was carried out.
After turning was started, when the boom of the crane formed a nearly right angle with the caterpillar, the stability was lost, the crane tilted, it bumped against the concrete wall of the still-water pond, and the boom was stopped.
The crawler crane driver had the license.
The slinging person had finished the course of the skill .
The weight of the mobile elevating work platform was 6.6 tons.
The crawler crane had 80 ton suspension, and the main booms were 47.85m, jib 13.7m, with offset
angles of 10 degrees. |
| Sequence |
From September 3rd, the carrying in and out work of mobile elevating work platforms to the pond was started.
Since then, carrying in and out work of mobile elevating work platforms had been respectively carried out 2 times until the day.
On that day, the over-load cutout device operated and the crawler crane stopped some times. But it was returned by raising the boom, and the work was continued.
On that day, the switch of outside display lamp of over-load cutout device was cut off.
The crawler crane was overturned while holding the aerial vehicle. |
| Cause |
There was no plan for the mobile elevating work platform in the work plan of the crane.
Carrying work of the mobile elevating work platform was not taken up in the previous arrangement conference.
The work director did not think about the load of the jib of the crawler crane.
The work director did not understand the rated load table because it was so complicated.
The crane work depended only on the crane driver.
The crane driver worked, depending on the over-load cutout device. |
| Response |
After the accident, the original contractor and the cooperation company gathered, and the accident review meeting was carried out.
After the accident, the safety education on crane work was carried out among the parties concerned. |
| Countermeasures |
During crane work, crane driver works as the over-load cutout device indicates.
The proper crane work plan is made, and after it is communicated properly to the party, the work is carried out.
Crane work planning is made within 90% of the rated load.
The outside overload display with a 3 color light is installed. |
| Knowledge Comment |
It is dangerous to use the over-load cutout device as a means of confirmation means of the rated load, because it is an alarm for the overload, and it is forbidden to be used. |
| Background |
Carrying in and out work of the mobile elevating work platform had already been carried out several times, and the party concerned seemed to have become careless.
Though the crane work plan had been made, it was formal and the important matter on the mobile elevating work platform was not described in it. In fact, as the over-load cutout device was seen, the work was carried out. |
| Sequel |
Most of overturning accidents and disasters involving transportable crane have arisen with the over-load cutout device OFF ( the switch cutting ). The work director tries to manage to carry out the schedule work, and he directs a crane driver to do so. Also, the crane driver thinks that he should come up to his director's expectation. Accidents and disasters seem to occur for that reason. |
| Scenario |
| Primary Scenario
|
Organizational Problems, Poor Management, Insufficient Analysis or Research, Insufficient Prior Research, Ignorance of Procedure, Disregard of Procedure, Malicious Act, Rule Violation, Failure, Fracture/Damage, Failure, Fracture/Damage, Loss to Organization, Economic Loss
|
|
| Sources |
the report of the accident investigation of Maeda Corp..
|
| Number of Deaths |
0 |
| Number of Injuries |
0 |
| Field |
Civil Engineering
|
| Author |
KITAJIMA, Munekazu (TEKKEN CORPORATION)
|
|
