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FACEValue: Construction worker dies after falling off concrete floor slab

NIOSH’s Fatality Assessment and Control Evaluation Reports

Date of incident: February 2007

A construction worker was killed after he fell off a collapsed, pre-cast concrete floor slab in a 10-story building construction site. The victim and a co-worker were working on the sixth floor, maneuvering the floor slabs into their final position before securing them to the steel framework. The slab was positioned on the steel structure frame of the building, but was not secured. As the workers walked toward the slab, it suddenly rotated downward to a near vertical position and became wedged between the steel supports. The co-worker secured himself with his elbows and climbed back up, but the victim fell to the floor below. The slab then fell on top of the victim and crashed through the slab below, causing the victim to fall to the third floor of the building. The co-worker removed the victim from the work area while another worker called 911. Emergency medical services arrived within minutes to transport the victim to a local hospital, where he was pronounced dead an hour later.

To prevent future occurrences:

  • Employers should ensure workers use personal fall arrest systems when working on pre-cast concrete floor slabs that are not permanently secured to steel framework. Before floor slabs are permanently secured to steel framework, they may not have the structural strength to safely support workers. The safety monitoring system and controlled access zones used in this case were not sufficient to protect workers from the fall hazard.
  • Employers should provide employees with training on the prevention of fall hazards associated with work on pre-cast concrete floor slabs. Training should inform employees not only of the necessity of using fall protection, but also to stand, walk and work only on slab areas that are supported by steel beams.
  • Pre-cast concrete erectors should secure slabs to the steel structure frame as soon as slabs are placed into their final position. Concrete erectors should grout or weld slabs to secure them to the steel framework as soon as possible. No more than three floors of unsecured slabs should be in place at one time at any stage of the construction process. In this case, slabs were erected up to the eighth floor without being grouted or supported with additional welded steel supports. The support strength of pre-cast concrete slabs should be evaluated, and supplemental fastening should be provided if necessary.

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