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The authors ask you:
Workers falling from unguarded edges and through unguarded holes and skylights accounted for a yearly average of 154 fatalities and 3,374 serious injuries (those involving days away from work) for the period 1998–2005. These occurred primarily in construction. Various products are commercially available to guard unprotected roof edges, holes, and skylights, but are not used regularly. A previous study conducted by NIOSH, Division of Safety Research investigated the strength of job-built guardrails and two commercial products. Along with results related to the overall strength of the guardrails, a new design of an adjustable roof bracket-safety rail assembly was also developed. The unique design is patent-pending in both the U.S. and Canada. The new design can be used on flat surfaces to guard holes and edges, and is also adjustable for seven roof pitches, ranging from 6/12 (27°) to 24/12 (63°, or A-frame). The bracket-rail system can be moved upslope on a roof to provide “on the spot” guardrail protection wherever needed. Discussions have been initiated with potential manufacturers to establish a partnership to commercially produce this fall-prevention safety system.
Analysis of data from the Bureau of Labor Statistics for the period 1998–2005 reveals that for all U.S. industries, an average of 154 workers were killed each year and a yearly average of 3,374 workers were seriously injured (that is, incidents involving a day away from work [DAFW] beyond the day of the injury) after falling from unprotected roof edges, or through unguarded roof holes and skylights. Roof-related fall injuries are also among the most severe occupational injuries when evaluated for the median number of DAFW. Injuries resulting from falls to a lower level through roof holes and skylights were 2 to 4 times more severe than all types of falls to a lower level in U.S. private industry, which was 12 days away from work per injury. The primary industry where these fatalities and serious injuries occur is in residential and industrial-commercial construction.
Current regulations for the construction industry are contained in 29 CFR (Code of Federal Regulations) Part 1926. Subpart M includes Sections 1926.500 through 1926.503 and Appendices A through E lists the requirements that are related to workplace falls. Section 1926.501 discusses requirements for fall protection. Subsection 1926.501(b)(4)(i) states that “Each employee on walking/working surfaces shall be (i.e., must be) protected from falling through holes (including skylights) more than 6 feet (1.8 m) above lower levels, by personal fall arrest systems, covers, or guardrail systems erected around such holes.” [restatement added] (Mancomm, p. 302) Also, the strength of guardrail systems must meet OSHA requirement 29 CFR 1926.502(b)(3): “Guardrail systems shall be capable of withstanding, without failure, a force of at least 200 pounds (890 N) applied within 2 inches (5.1 cm) of the top edge, in any outward or downward direction, at any point along the top edge.” (Mancomm, p. 303)
There are a variety of commercial products available for use in guarding unprotected edges of roofs, decking, or interior surfaces before construction is completed. Some products can only be used on flat surfaces, while others can be used on sloped residential roofs with adjustability for just a few roof pitches. Often, when the products are installed on a pitched roof, they are configured only as a slide guard. In that arrangement, the product does not have a vertical rail component to support horizontal cross rails for a guard rail system. For those commercial roof brackets that do provide a horizontal guardrail system, the vertical height of the top rail often does not meet requirements of the OSHA standards for proper worker protection as a guardrail.
These design deficiencies were identified during a previous research study conducted by the Division of Safety Research of the National Institute for Occupational Safety and Health which investigated the strength capabilities of job-built and commercial guardrails as perimeter guarding systems. The output of that previous research study was a unique patent-pending design of an adjustable roof bracket-safety rail assembly. This prototype design meets all applicable OSHA requirements and has been tested extensively in the NIOSH Morgantown lab.
Adjustable guardrail system installed on a 45°-slope simulated roof work site
NIOSH researcher assembling roof brackets that will be used on a residential construction site
The NIOSH-designed roof bracket-safety rail assembly being installed on a residential work site for fall-prevention purposes
A previous NIOSH, Division of Safety Research project evaluated the effectiveness of two commercial fall-prevention guardrail systems, which were designed for edge use, when they were installed as guardrails around a hole in a simulated roof work site. That study evaluated the two commercial systems and a typical “job-built” guardrail (made of two-by-fours) to determine the effectiveness of meeting the OSHA requirement of 200 lbs at the top rail and determine the overall strength of the three systems.
The 200-lb point load on the top rail was generated by using a fire rescue test manikin, which is a canvas human form that was filled with rubber pellets and sand to provide its shape. The manikin was mounted on a steel frame that was hinged at the knees to best recreate the motion of a human tripping and falling against the guardrail set-up. The overall strength of the guardrails that were constructed was evaluated by a pull-to-failure test (PTF), which was devised by the research team. The PTF test imposed a larger, more sustained force to the center of the top rail.
All of the different guardrail configurations that were constructed supported the 200-lb and greater loading that was generated by the falling manikin. The pull-to-failure test evaluated how well the guardrail system was constructed as a unit and how well the upright supports were anchored to the roof test fixture. The two commercial products were typically stronger and generated more consistent results than the job-built guardrails. Despite a range of values for the job-built versions, they performed quite adequately during the testing.
A more important result than the values generated by the testing was the development of a novel design of roof bracket that incorporates design features from both of the commercial products.
This led to a new research project that had the objective of developing and improving the design of an adjustable, easily installed, easy-to-move bracket that incorporated a guardrail system into the design. A set of brackets can be installed on 8-ft spacing to support a walking/working surface. As the bracket is moved to different work sites, the guardrail system will move with it. This system has been designed for use on 7 roof slopes, ranging from 6/12 (27°) to 24/12 (63°, or A-frame) and also on flat wood or concrete work surfaces.
A set of four roof brackets with corresponding vertical rails and horizontal cross members can be positioned at each corner of a roof opening (such as for a dormer, chimney work, or skylight installation) to provide the worker with a level working surface and "on-the-spot" guardrail protection (see photos). If a worker loses his/her balance, the fall is prevented immediately, not after sliding down-slope to the bottom edge of the roof. The unique design of the support brace for the horizontal cross members can be adjusted up and down the vertical safety rail to provide a top-rail setting at 42 ± 3 inches, as required by OSHA on sloped roofs.
When commercially available, residential and industrial-commercial construction workers will have an all-purpose fall-prevention system. If used routinely, it has the potential of preventing dozens of deaths and hundreds of serious injuries caused by falling from heights. This can result in potential savings of $$millions to construction companies through reductions in survivors' benefits, workers' compensation costs, medical costs, and related indirect costs. This is based on an estimate of $100,000 per fall-related incident (Liberty Mutual, 2002).
Future plans:
Liberty Mutual Workplace Safety Index Fact Sheet, 2002.
Mancomm (Mangan Communications, Inc.), “Subpart M.” 29 CFR
1926, OSHA Construction Industry Regulations, Davenport, Iowa, 2002, p.
302. http://www.mancomm.com
The findings and conclusions in this poster are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these Web sites.
