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I-beam fell from outrigger on roof, striking worker below

Date of incident: September 2014
Notice of incident number: 2014117080079
Employers: Construction labour supply company; company providing outriggers; glass installation company

Incident summary
A building higher than 20 storeys was under construction. Workers were installing glass curtain walls on the top floors. Two outriggers positioned on the rooftop were used to lift the curtain walls and put them in place. The outriggers extended out past the perimeter of the roof, so the materials and components were lifted clear of the exterior walls. Each outrigger was constructed of aluminum I‑beams that were secured on top of two scaffolds. As a curtain wall was being raised, the back end of the outrigger lifted off the rear scaffold. The outrigger slid forward and the I‑beam fell from the outrigger system. The I‑beam struck a construction worker who was assembling fence panels on the street level to block off public access to the construction site. The worker was seriously injured.

Investigation conclusions
Cause

  • Inadequate assembly resulted in failure of outrigger equipment: The outrigger equipment was not properly assembled, and it collapsed during the lifting of a curtain wall, seriously injuring a worker below. This outrigger equipment was not erected in accordance with the manufacturer’s instructions.

Underlying factors

  • Danger area not adequately assessed: There was a designated danger area on the street level, but it had not been adequately assessed and was not large enough to effectively protect workers. The location where the worker was working and struck by the I‑beam was outside of this designated danger area.
  • Inadequate supervision: Both the company providing the outriggers and the glass installation company failed to provide adequate supervision in the assembly and use of the outrigger equipment. The glass installer ought not to have used the outriggers until the firm’s workers were adequately trained. The company providing the outriggers did not ensure the outriggers were erected as required by the manufacturer.

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Publication Date: Dec 2017 Asset type: Incident Investigation Report Summary NI number: 2014117080079