As previously mentioned, the leading cause of death in construction work is falls from elevations. Today, we’re going to take a closer look at the safety systems implemented to help prevent worker falls. (Fellow InjuryBoard blogger, Justin Rogers, also has a series of fall prevention blogs.) When workers at construction sites are exposed to vertical drops of at least 6 feet, OSHA requires the use of at least one of the following: guardrail systems, safety net systems, personal fall arrest systems.
Guardrail systems is the first type of protection and may be the most commonly recognized by the general public as they walk past construction sites. If used, guardrails should be placed around the hazard area before work begins. When using a guardrail system, OSHA standards must be met. First, the top edge height of the top rails must be between 39 and 45 inches above the walking/working level. If there is no wall or other structure of at least 21 inches in height between the top edge and the walking/working surface, then the employer must install midrails, screens, mesh, intermediate vertical members, or other equivalent structures. (This will fill the railing gaps so the worker can’t slide off past the guardrail.) OSHA allows each site to pick the type of guardrails it would like to use, so companies in the business of providing fall protection equipment offer varying types of guardrail systems, such as a roofing guardrail system or portable guard rails. However, each system must be capable of withstanding at least 200 pounds of force applied within 2 inches of the top edge. This force must be withstood in any direction and at any point along the edge. Similarly, if the system has to be supplemented with midrails, screens, mesh, or other structures, these structures must be able to withstand at least 150 pounds of force applied. OSHA does not allow guardrail systems to have rough or jagged surfaces because they could cause punctures, lacerations, or snag clothing. Finally, top rails and midrails cannot overhang the terminal posts.
The next line of protection is safety net systems. Safety nets are installed under the surface on which employees are working. OSHA wants the nets installed as close to the surface as possible. From the outermost point of work area, the nets must extend outward according to the vertical distance from the working level to the horizontal plane of net. Safety nets need to be drop-tested at the construction site by using a 400 pound bag of sand 28-32 inches in diameter. The nets must be able to absorb an impact force equal to the drop test described. Only after the net passes the test can an employer draft a certification record. The most recent certification record must be available at the construction site for inspection. However, safety nets must continue to be inspected for wear and tear or any damage. Additionally, each section of safety net must have a border rope (for webbing) with a minimum breaking strength of 5,000 pounds. The above tips are merely basic OSHA standards; for more precise instructions and regulations, please click here.
Finally, if the first two systems were not implemented, OSHA will allow the use of personal fall arrest systems. There are several components to this third alternative, including: an attachment location, body harness, vertical lifeline/lanyard, webbing, anchorages, horizontal lifeline, and connectors. To use personal fall arrest systems safely, you must limit the maximum arresting force to 1,800 pounds. The system must be rigged so that, upon fall, the employee will not contact any lower level nor free fall more than 6 feet. The employee must be brought to a complete stop upon 3 ½ feet distance. The system itself must be strong enough to withstand twice the potential impact of a worker free falling or the free fall permitted by the system, whichever is less. Systems should be inspected prior to each use. Once the system has been subjected to fall impact, do not use the same equipment. Although OSHA allows a variation of the fall protection systems to be used, an employee should never attach a fall arrest system to a guardrail systems or hoists.
Even though OSHA permits any of the systems to be used, local area zoning or permits may restrict the construction contractor’s choice. Also, OSHA recommends using a guardrail system over the second options because the guardrail system prevents falls which may deter injury. Safety nets and personal fall arrest systems are fall protection systems that will mitigate injury after the worker has already fallen. Either way, utilizing any of these systems will certainly result in a better outcome than using none. And remember, if you’re working near a six foot drop, OSHA mandates system protection use!