| Case Name |
The fall accident during the bolting work of the steel column on the steel beam. |
| Pictograph |
|
| Date |
February 3, 1999 |
| Place |
Zama City, Kanagawa Prefecture. |
| Location |
The 12-floor condominium construction site. |
| Overview |
During the steel erection work of the 12-floor condominium construction, the workers were engaged in the operation to join the third part (floor 7th-9th) of the steel column to the second part (floor 4th-6th) which had already been temporarily established with bolts. Then, the worker used the safety belt, the rope at which was threaded through the trap installed in the steel column. The safety belt was suspended in a `U' shape. And a part of the mounting ring (carabiner) had transformed and broke off. The worker who had been engaged in the operation fell to the ground 17m below. |
| Incident |
In the morning of February 3rd, 1999, during the steel erection work of the 12-floor condominium construction, the second part of the steel column (floor 4th-6th) which was the center of the building had already been established the day before. So, the workers were trying to assemble steel frameworks of the 3rd part (floor 7th-9th) on that day. The workers lifted the 3rd part of the steel column by the transportable crane and hung the safety belt on the main rope or the trap to go up and down on the steel beam of the 6th floor. And they jointed temporarily the 3rd part of the steel column to the 2nd part with attached boards and bolts. There was not enough scaffold space for a worker to temporarily join columns with bolts. So, he hung the hook of the safety belt on the ring to install tools of his belt (carabiner) after he threaded the rope of his safety belt through the trap of the steel column. And he was engaged in the operation suspending the rope in a `U' shape, and giving his weight to the rope of his safety belt. At that time, the part of the ring (carabiner) transformed and broke off. He fell about 17m to the ground. |
| Sequence |
* He hung the hook of the safety belt on the ring to install the tools of his belt (carabiner) after he threaded the rope of his safety belt through the trap of the steel column.
* The safety belt was usual safety belt for unifilar suspension, and he carried out his work, leaning his weight on the belt which was suspended in a `U' shape.
* The ring to install tools of his belt (carabiner) of the safety belt he used transformed and expanded because of his weight etc. Consequently, the hook came off and he fell about 17m down onto the ground. |
| Cause |
* Because the ring (carabiner) of the safety belt he used transformed, and the hook came off, he fell down.
* He didn't use the safety belt which had a structure and standard enough to sustain the weight using the condition of `U-suspension'.
* The safety belt didn't have the double equipment to prevent unfastening. It was the adaptation from `unifilar-suspension'. He arbitrarily attached the ring which didn't accommodate to `the standard of the safety belt' .
* Beforehand, they had not determined a work planning including methods of the work, the way to put main ropes for fall prevention.
* The safety guard and the main rope were not set up.
* The chief operator of the steel assembly didn't check the function of the safety belt and didn't observe the condition by which the workers used safety belts. |
| Countermeasures |
* When they carry out the work to construct the steel of buildings and so on, they must determine a work planning showing methods and procedures to work, and the way to set up equipments to prevent falls, beforehand. They must carry out their work according to work plan.
* When they work at the place where workers have possibility to fall down, the work floor and the safety guard must be set up and workers must use safety belts surely and effectively.
* If workers try to operate using safety belts under the condition of `U-suspension', they have to use safety belts which have structures and standards designed to be used under the condition of `U-suspension'.
* They must not use the safety belt which does'nt reach `the standard for the safety belts' when they use and manage safety belts. |
| Knowledge Comment |
* Don't convert the safety belt which is used under the condition of `unifilar suspension' and don't attach the part which does'nt reach `the standard for the safety belt'!
* The chief operator for making up steel has to check the condition of using safety belts and be thorough in the management. |
| Background |
In the background of this labor accident, there seems to be the following problems.
* The worker used his safety belt to which he attached some tools arbitrarily after he bought it to work on the condition of `U-shape-suspension' easily.
* Don't entrust inspection and management of safety belts and observation of the condition of use to the chief operators! And the people in charge of the contractor and the subcontractor (the foreman, safety and health controller) have to be thorough in the management and recognize them as their own problems. |
| Sequel |
* They were found guilty of executive punishment.
* There happened the same kind or similar disasters happenned frequently in Japan. So, in one city, the major general construction companies established `Research and examination committee for the safety belt and so on.' and embarked on a survey of the actual situation. And, the guideline of the management should be shown based on the result of the actual situation survey. |
| Incidental Discussion |
* There were many workers who affirmed they had hung `U-hang' using carabiners converted similarly. Workers explain that they can work easily and use both hands. Workers don't recognize danger to themselves much. |
| Reason for Adding to DB |
* The same kind or similar unsafe, actions, and the accident disasters of the same kind or similar must not recur! |
| Scenario |
| Primary Scenario
|
Ignorance, Insufficient Knowledge, Insufficient Analysis or Research, Insufficient Prior Research, Misjudgment, Misunderstanding, Organizational Problems, Poor Management, Organizational Problems, Inflexible Management Structure, Poor Value Perception, Poor Safety Awareness, Malicious Act, Rule Violation, Regular Movement, Dangerous Movement, Planning and Design, Poor Planning, Bodily Harm, Harm to Physical Well-being, Bodily Harm, Death
|
|
| Sources |
* Safety and Health Information Center (the case of labor accident)
|
| Number of Deaths |
1 |
| Number of Injuries |
0 |
| Physical Damage |
None |
| Financial Cost |
Unknown |
| Economic Loss |
Unknown |
| Consequences |
This disaster was taken up in the technical paper, and there are many responses because of the necessity of making guideline, for the prevention of a recurrence. |
| Field |
Civil Engineering
|
| Author |
KANO, Koji (Japan Construction Safety and Health Association)
|
