CASE #265
CASE #265 – Three crushed by falling block wall
A 24-year-old labourer and a 37-year-old pipefitter were crushed by a falling block wall when it failed; they died of their injuries immediately. A 46-year-old utility foreman was injured.
At the time of the incident, the labourer was applying caulking to the expansion joints of the wall. The pipefitter and foreman were installing piping for the building’s sprinkler system in a trench next to the wall. A wind gust caused the block wall to fall onto all three. The project superintendent called 911, and emergency medical services arrived within 4 minutes. The labourer and pipefitter were pronounced dead at the scene, and the utility foreman was airlifted to a local hospital.
Occupational injuries and fatalities are often the result of one or more contributing factors or key events in a larger sequence of events that ultimately result in the injury or fatality. Investigators identified numerous unrecognized hazards as key contributing factors.
The clip and clip point were undamaged and remained connected throughout the incident. Also, the folded fabric portion of the lanyard had its plastic covering and stitching still intact. The anchor plate was attached directly to the leading corrugated decking sheet, about 18 inches from the edge.
The employer and employees were under the impression that the screws they used for the plate were of an appropriate length. The second worker also wore a retractable lanyard but his fall arrest system was attached to a beam clamp and not exposed to the leading-edge hazard.
The employer’s protocol for laying corrugated roofing materials requires that the leading edge of the decking not be secured until the next sheet is in place. Each metal sheet was fastened on the following end and anywhere else it was supported by a truss. The next sheet was then placed over the leading edge and attached with fasteners. This was continued until the roof was complete.
On the day of the incident, for an unknown reason, the victim fell from the leading edge. When his retractable lanyard reached the end, the anchor plate was pulled completely out of the decking, allowing the worker to fall 40 feet to the ground.
This incident illustrates the need to take these preventive measures:
- Guards and protective devices must be properly designed/constructed, fitted, securely held in place, not easily defeated, located at an adequate distance from the danger zone and cause minimum obstruction to view the production process/hazard.
- Conduct a hazard analysis with worker participation that focuses on the relationship between the workers, the task, the tools and the environment.
- Consider the entire machine operation production process, the machine modes of operation, individual activities associated with the operation, servicing and maintenance activities. The results from the analysis may then be used as a basis to design machine safeguarding and overall hazardous energy control measures.
- Establish an effective hazardous energy control program (Lockout/Tagout/Verify) to complement machine safeguarding methods.
Un ouvrier de 24 ans et un tuyauteur de 37 ans ont été écrasés par la chute d’un mur de blocs lorsqu’il s’est rompu; ils sont morts immédiatement de leurs blessures. Un contremaître des services publics de 46 ans a été blessé.
Au moment de l’incident, l’ouvrier appliquait du calfeutrage aux joints de dilatation du mur. Le tuyauteur et le contremaître installaient la tuyauterie du système de gicleurs du bâtiment dans une tranchée à côté du mur. Une rafale de vent a fait tomber le mur de blocs sur les trois. Le surintendant du projet a appelé le 911 et les services médicaux d’urgence sont arrivés dans les 4 minutes. L’ouvrier et le tuyauteur ont été déclarés morts sur les lieux, et le contremaître des services publics a été transporté par avion vers un hôpital local.
Les accidents du travail et les décès sont souvent le résultat d’un ou plusieurs facteurs contributifs ou événements clés dans une séquence plus large d’événements qui aboutissent finalement à l’accident ou au décès. Les enquêteurs ont identifié de nombreux dangers non reconnus comme principaux facteurs contributifs.
- Assurez-vous que les employés suivent les dessins d’ingénierie/architecturaux pendant la construction du bâtiment et obtenez l’approbation de l’ingénierie avant d’apporter des modifications au plan.
- Élaborez et suivez un plan de contreventement des murs en maçonnerie, formez les employés sur le contreventement approprié des murs en maçonnerie et assurez-vous que les murs en maçonnerie sont correctement contreventés tout au long du projet.
- Développer et implanter une zone d’accès restreint/limité.
- Former les travailleurs sur les dangers liés au travail à proximité de murs de maçonnerie non soutenus.
- Désignez une personne compétente formée pour surveiller la vitesse du vent.
- Planifier les tâches de travail pour limiter l’exposition des travailleurs non essentiels aux dangers posés par les murs de maçonnerie en construction.