Date of incident: February 2015
Notice of incident number: 2015173340112
Employer: Machine shop

Incident summary
A worker was installing sections of metal floor grating on a conveyor tower that was under construction. While carrying a piece of grating, the worker stepped on a piece of grating that had been laid down but not yet fastened in place. The worker and this loose piece of grating both fell 7 feet through an opening to the ground below. The worker was struck by the piece of grating he had been carrying and received serious crushing injuries.

Investigation conclusions
Cause

• Insufficient overlap of grating on beam caused grating to shift when stepped on: The worker stepped on a piece of grating that had been laid down but not yet fastened in place. The piece of grating had only 3/8-inch overlap on one end. When the worker stepped on it, the grating shifted, and he and this loose piece of grating both fell 7 feet through the opening to the ground below.

Underlying factors

• Failure to install a temporary floor: The failure to install a temporary floor during the initial stages of the grating installation meant that there was no work platform stable or large enough for the worker to safely move about. A temporary floor would have provided a safe area for the worker to deal with improperly fitting sections and sections that were delivered out of order to the work area.
• Positioning of grating: Given the weight and dimensions of each section of grating, the pieces of grating should have been carried and placed in position by two workers. This would have reduced the potential of having a single worker drag the grating across insecure sections, unintentionally moving them out of their proper position.

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