Case Ditails

Scenario
Case Name A wire rope for hitching broke, and the retaining wall was lifted by a drag shovel and fell down. A worker was crushed under it.
Pictograph
Date November 2, 1998
Place Saga Prefecture.
Location The road construction site of abutments attachment
Overview In the road construction site of abutments attachment, on the downhill side of the road to attach the right side, workers hung the wire rope in order to hitch on the attached hook the bucket of the drag shovel; They hung the wire rope run into the drain hole of the retaining wall, and lifted the retaining wall in order to gather one of the retaining walls put in the position where an L form retaining wall was to be installed. Then, the wire rope for hitch had broke around the hook, and the retaining wall fell down. The worker who had signalled, was crushed under the retaining wall.
Incident On the afternoon, November 2nd, 1998, on the road construction site of abutment attachment, the workers were engaged in the operation to install a L form retaining wall (2*2*1.6m, Weight; 2.65t) on the shoulder of the road. When the work started, they determined that they would move the retaining wall to the side which had already been put in the position to be installed because they would try to install concrete in the sand bed where the retaining wall was to be installed. They would carry out this work by using a drag shovel. When the loads were lifted about 1.6m up, the wire rope for hitching, through the drain hole of the L form retaining wall, broke and the lifted L form retaining wall fell down. The worker who had signalled to the operator of the drag shovel, fell on his back on the foundation of the retaining wall and he was crushed under it.
Sequence * Two joints at the both ends of the wire rope (this rope is 5m long and has joints at its ends) were put through the drain hole from behind the L form retaining wall.
* The worker hung the wire rope for hitching, on the hook attached to the bucket of the drag shovel, and hung the wire rope which edges had meshes.
* By the signal from the worker, the worker lifted up the L form retaining wall with the arm of the drag shovel.
* When he lifted the retaining wall by about 1.6m, the wire rope for hitching broke around the hook.
* The worker who had signalled was crushed under the L form retaining wall.
Cause * The weight of the retaining wall was 2.65t, and the drag shovel had the ability to lift about 1.3t loads at most. And, it was the overload for the drag shovel. But, the worker overlooked this overloading. He used the drag shovel, disregardinng the weight limit to be able to lift the load under 1 ton, which had been determined as a requirement to operate this drag shovel in improper use.
* The worker didn't know the weight of the load and the strength of the wire rope for hitching etc. because he didn't have appropriate qualifications. Then, he carried out the hitch work, using it as a suspension tool.
* The worker had passed through the operation skill classes of car-type construction equipments (for leveling of the ground, for the transportation and the loading, for the excavation). But he didn't have the necessary qualification for the hitch work.
* He used the wire rope which was very corroded. There was a line seedmed to have a division line which had arose in the broken part before.
* The superviser of the site of the contractor, had changed the work plan of the day, but he didn't point out indication matters and didn't take measures to meet the change of the work. Then, he overlooked the overloaded drag shovel, operated improperly.
Countermeasures * As a rule car-type construction equipments like drag shovels must not be operated improperly.
When workers unavoidably use the machine to lift loads, they have to keep to the weight limit determined by machine structures etc.
The maximum weight that they can lift loads is under 1 ton must be known to everyone in the site.
* In the hitch work, they have to confirm that the condition of the wire ropes for hitch, is safe, and only then use them.
* They have to check the wire ropes for hitching periodically and strictly before their use,. And they have not to use tools which are damaged remarkably and unsuitable.
* When workers try to lift loads by operating car-type construction machines,the worker who is going to hitch must be a person who has passed through the hitch skill classes.
* In the work of lifting loads, they must not have people enter in the zone where a fall accident may happen.
* In the case of changing the work plan, they have to examine the safety measures in relation to the new work, and have all concerned workers understand the procedure completely.
Knowledge Comment * They must be thorough in prohibiting the improper use of car-type construction machines, as a rule.
* In the case of hitch, they must ,completely check wire ropes, confirm the weight limit to lift, and have qualified workers operate.
Background * The construction which L form retaining wall is attached is rhe work carried out for long term, so they must definaitely use a transportable crane, certainly. And they should prepare and attach the facility and equipment exclusive to lifting.
They tend to substitute the drag shovel by them like this situation, carelessly. This is a large problem to overcome.
* The construction industry don't try to improve the situation at all though similar accidents depending on improper uses have happened many times.
* The Civil Service handed out the administrative punishment to apportion the responsibility of safety management in the improper use of car-type construction machines and so on.
Reason for Adding to DB * We decided to introduce the accident case to eradicate similar disaster and for instructions.
Scenario
Primary Scenario Misjudgment, Misjudgment of Situation, Misjudgment, Narrow Outlook, Ignorance, Insufficient Knowledge, Organizational Problems, Poor Management, Poor Value Perception, Poor Safety Awareness, Insufficient Analysis or Research, Insufficient Prior Research, Non-Regular Action, Change, Regular Movement, Dangerous Movement, Usage, Maintenance/Repair, Failure, Fracture/Damage, Bodily Harm, Harm to Physical Well-being, Bodily Harm, Death
Sources `Let's study in the case' safety countermeasure construction labor accident prevention association edition (from disaster case NO.22)
Number of Deaths 1
Number of Injuries 0
Physical Damage a L form retaining wall and so on.
Financial Cost unknown
Economic Loss unknown
Consequences In the construction industry, accidents of construction machines have happened many times. The social influence is big because they don't improve this situation.
Field Civil Engineering
Author KANO, Koji (Japan Construction Safety and Health Association)
Scenario