A review of the engineering, PPE and administrative options for preventing falls.
Falls are the leading cause of death among construction workers. They account for one-third of all construction fatalities and cause more than 68,000 serious injuries each year.
Not surprisingly, an OSHA study of almost 100 fall-related fatalities showed that virtually all of those deaths could have been prevented if fall protection, such as guardrails, personal fall arrest systems, safety nets, or hole covers, had been used.
How Fast Do You Fall?
Gravity's not just a good idea, it's the law! And remember, it's not the fall that's the problem. It's the sudden stop. And just how suddenly do you stop?
Those of you who had high school physics may recall that the velocity (v) of a falling body may be calculated by the equation: v= *2gh, where (g) is the gravitational constant 32 ft/sec2 and (h) is the height of the fall in feet. So if you know how high you are, you can easily figure out how hard you'll hit the ground.
For example, consider a measly 10-foot fall. Just before you hit the pavement, you're moving at about 25 ft/sec (2 x 10ft x 32ft/sec2 = 640 ft2/sec2 = 25 ft/sec). That's the same as 17 miles per hour. You can get some idea of the benefit of using fall protection when you think about what would happen to your car if it slammed into a brick wall at 17 miles an hour.
In general, OSHA's fall protection standard requires that anyone working at heights of 6 feet or more be provided with fall protection. Although this "six foot rule" is widely touted as an acceptable threshold, remember that the laws of physics are immutable, and that falls from less than 6 feet have painful consequences.
Fall Protection Options
OSHA's fall protection standard like most of the regulations the agency has issued over the last 20 years is performance-oriented. In other words, it sets a broad goal you must achieve protecting employees from fall hazards but it doesn't give two hoots about how you do it. In fact, the rule offers a staggering array of methods that may be used. They include:
Fall prevention methods, such as guardrails, warning lines, controlled access zones, and safety monitoring systems.
Fall-arrest systems, such as safety nets and full-body harnesses.
Fall protection plans, which are administrative controls that rely on special training and work practices.
Guardrail systems are simply barriers that prevent employees from falling to lower levels. They consist of up-rights, top-rails and mid-rails, mesh or screening placed between the top rail and the walking surface. The edge of the working level must also be provided with a toe-board if tools or materials could slip off and fall on workers below.
Top-rails. Top edges of guardrails must be between 39 inches and 45 inches high and be able to withstand a 200 pound force applied outward or downward along the top edge. The top edge may not deflect to less than 39 inches under this load.
Intermediate Members. Unless there is a 21-inch high wall or parapet located between the working surface and the top rail, mid-rails, screens, mesh or intermediate vertical members must be installed between the top rail and the working surface.
Mid-rails must be positioned midway between the top-rail and the working level. If screening or mesh is used instead of mid-rails, it must cover the entire opening formed by uprights, top-rail and working level. If intermediate members, such as balusters, are used, they can't be spaced more than 19 inches apart.
Mid-rails, screens, mesh or other intermediate members must be capable of withstanding a downward or outward force of at least 150 pounds.
Toe-boards. Toe-boards must be a minimum of 3-1/2 inches high and have no more than 1/4-inch gap between them and the working surface. If they are made of mesh, the openings may not be bigger than one inch. They must also be able to withstand a downward or outward force of at least 50 pounds.
Surface Preparation. Guardrail surfaces must be finished to prevent cuts, punctures or lacerations and to prevent snagging of clothing. The ends of all top -rails and mid-rails cannot hang over the terminal posts unless the overhang would not pose a hazard.
Rope and Banding. Wire rope may be used for guardrails, provided that it is at least 1/4 inch in diameter to prevent cuts and lacerations and it's marked or flagged at not more than 6-foot intervals with high-visibility material.
Manila, plastic or synthetic rope may be used for guardrails, provided it is inspected frequently enough to ensure that it retains its strength. Steel and plastic banding may not be used.
Employees who may be exposed to fall hazards must be trained to recognize the hazards to which they may be exposed. They must also be able to demonstrate proficiency in the use of fall protection systems.
Training Requirements. Specifically, each employee must be trained by a competent person on the
- General requirements of the OSHA fall protection standard.
- Nature of fall hazards in the work area.
- Correct procedures for erecting, maintaining, disassembling, inspecting and using fall protection systems used.
In addition, training must be provided on the following items, when applicable:
- Role of each employee in the safety monitoring system.
- Limitations on the use of mechanical equipment during the performance of roofing work on low-sloped roofs.
- Correct procedures for the handling and storage of equipment and materials and the erection of overhead protection.
- Role of employees in fall protection plans.
Training Documentation. The training must be documented by a record that contains the name or the identity of the employee trained, the date the training was provided, and either the signature of the person who conducted the training or the signature of the employer.
Retraining. Retraining must be provided whenever there is evidence that an employee who has been previously trained no longer possesses the requisite knowledge and skills. It is also required if there are changes in the workplace or changes in the types of fall protection systems or equipment that render previous training obsolete.
Warning lines are barriers placed around a roof to alert employees that they are approaching an unprotected edge. They also identify roof areas where work may be performed without guardrails, body belts or safety nets.
Lines. Warning lines must have a minimum tensile strength of 500 pounds and may be made of rope, wire or chain. They must be also marked or flagged at not more than 6-foot intervals with high-visibility material. Lines must be rigged and supported in such a way that their lowest and highest points are no more than 34 inches and 39 inches, respectively, above the surface.
Supports. Lines supported by stanchions must be installed so that the slack between two stanchions can't be taken up before the stanchions tip over. Stanchions must be able to withstand a 16-pound horizontal force applied 30 inches above the working surface. The force must be applied perpendicular to the warning line and in the direction of the roof edge.
Installation. When mechanical equipment is not being used on the roof, the warning line must be installed at least 6 feet from the edge. When mechanical equipment is used, the warning line must be installed at least 6 feet from the edge of the roof edge parallel to the direction of the equipment's movement, and at least 10 feet from the edge perpendicular to the direction of movement.
Controlled Access Zones
Controlled access zones also are areas where certain work may be done without the use of guardrails, personal fall arrest systems, or safety nets. However, unlike a warning line, which is barrier that cannot be crossed, a controlled access zone establishes a boundary that can be crossed, but only by a specifically designated employee.
General requirements for lines and stanchions are similar to warning lines, except that the minimum breaking strength for lines is only 200 pounds. Lines must be rigged and supported in such a way that the lowest and highest points are no more than 39 inches and 45 inches above the surface, except that 50 inches is allowed for overhand bricklaying.
On floors and roofs where guardrails are not in place, controlled access zones must include all points of access, material handling areas and storage areas. On floors and roofs where guardrails are in place, but need to be removed to allow bricklaying or leading edge work, only the portion of the railing that permits that day's work may be removed.
Control lines may not be located less than 6 feet, nor more than 25 feet, from leading or unprotected edges. However, when precast concrete members are being erected, the lines may not be less than 6 feet, nor more than 60 feet or half the length of the member being erected whichever is less, from the leading edge.
The control line must run approximately parallel to the entire length of the unprotected or leading edge. The controlled access zone must be defined by a control line erected not less than 10 feet nor more than 15 feet from the working edge.
The control line must extend for a distance sufficient to enclose all employees performing overhand bricklaying and related work at the working edge, and it must be approximately parallel to the working edge.
Safety Monitoring Systems
A safety-monitoring system is an administrative control that allows a competent person to watch employees and warn them if they get to too close to an unprotected edge. The competent person must be specifically designated to serve as the safety monitor and must be on the same working level and within sight of the employees being monitored. Monitors must also be close enough to communicate with employees orally and may have no other responsibilities that could divert their attention from monitoring duties.
An incredible number of fall incidents have occurred because employees have fallen thorough a hole. Consequently, open holes must be protected.
Hole covers located in traffic areas must be able to support at least twice the maximum axle load of the largest vehicle expected to cross over them. Other covers must be able to support at least twice the weight of employees, equipment, and materials that may be imposed on them.
Covers must be secured to prevent accidental movement by wind, equipment, or employees, and be color-coded or marked with the word "HOLE" or "COVER" to provide warning of the hazard.
What if fall protection is not really practical?
OSHA recognizes that, in some cases, it may simply be impossible to provide fall protection. In those cases, hazards may be managed by a fall protection plan. These plans may only be used for leading edge work, precast concrete work and residential construction and, then, only if conventional fall protection equipment cannot be used or creates a greater hazard.
Fall protection plans must meet the following requirements:
- Be prepared by a qualified person and developed specifically for the site where the work is being performed
- Explain why the use of conventional fall protection systems, such as guardrail systems, personal fall arrest systems, or safety net systems are infeasible or why its use would create a greater hazard.
- Explain the measures that will be taken to reduce or eliminate the fall hazard for workers who cannot be provided with protection from the conventional fall protection systems. For example, the extent to which scaffolds, ladders or vehicle-mounted work platforms can be used to provide a safer working surface and reduce the hazard of falling.
- Identify each location where conventional fall protection methods cannot be used. These locations must be classified as controlled access zones.
- Maintain up-to-date records with any changes approved by a qualified person.
- A copy of the plan with all approved changes must be available at the jobsite.
- The plan shall must be implemented under the supervision of a "competent person."
Safety Net Systems
Anyone who has ever seen a trapeze or high-wire act intuitively appreciates the purpose of safety nets. While nets are seemingly simple devices, there are a number of important considerations governing their use.
Net Construction. Mesh openings may not be larger than six inches on a side, and crossings must be secured to prevent enlargement. Each net section must be provided with a border rope or webbing with a minimum breaking strength of 5,000 pounds. Connections between net panels must be as strong as integral net components and can't be spaced more than six inches apart.
Installation Requirements. Nets must be installed as close as practicable to the level where employees are working, but never be more than 30 feet away. The potential fall zone must also be unobstructed, and there must be sufficient clearance to prevent nets from hitting the surface when subjected to the drop-test described below.
Drop Test. A drop-test must be conducted unless it can be shown that it is unreasonable to perform. Nets must be able to survive being hit by a 400-pound sand bag, measuring between 28 and 32 inches in diameter, dropped from the highest surface where employees are exposed.
Net Certification. A "competent person" must inspect the net and certify that it is in compliance before it is used. Nets must also be inspected whenever relocated, after a major repair and at 6-month intervals if left in one place.
Certification record. A record that shows net installation and the date it was certified must be prepared. The most recent record must be available at the job site.
Inspections. Nets must be inspected at least weekly for wear, damage and signs of deterioration. They must also be inspected after any occurrence which could affect their integrity, such as impact, chemicals splash, heat damage, cuts or abrasions.
Work Practices. Defective nets may not be used, and damaged components must be removed from service.
Construction materials, scrap pieces, equipment and tools which have fallen into the net must be removed as soon as possible, and at least before the next work shift.
What are leading and unprotected edges?
Unprotected edges are the edges along the perimeters of roofs, floors, decks, platforms, ramps and floor-openings that employees may fall through or from. Unlike leading edges, they are static environments.
Leading edges are dynamic environments. They are edges of floors, roofs, decks or other walking-working surfaces which move or change location as additional sections are constructed. For example, each time a piece of plywood is placed on floor joists, the relative position of the unprotected edge changes. A leading edge is considered to be an "unprotected side and edge" during periods when it is not actively and continuously under construction.
Personal Fall-Arrest Systems
A personal fall-arrest system consists of a full body harness and associated hardware that slows a worker's rate of descent and keeps him from hitting the ground. Personal fall arrest systems are different from positioning devices, such as body belts, which allow employees to work on elevated vertical surfaces, such as walls and telephone poles, with both hands free.
Two innovations which have changed the face of fall protection are self-
retracting lifelines and energy absorbing lanyards.
Self-retracting lifelines are deceleration devices that contain a drum-wound strap or wire rope that moves in and out of the case under the tension posed by employee movement, much like the shoulder strap on a car seat belt. If an employee falls, the inertial mechanism automatically locks the drum, arrests the fall, and limits the free fall distance to two feet.
Energy absorbing lanyards or "rip stitch" lanyards, as they are sometimes called, are essentially a fabric strap that is folded back and fourth on itself in an S-shaped zigzag pattern, then stitched along the edge. The shock imposed by a fall breaks the stitching and the webbing unfolds like an accordion to dissipate the energy and absorb the impact load.
Equipment Inspection. Personal fall arrest systems must be inspected prior to each use for wear, damage and other deterioration, and defective components shall be removed from service.
Anchorage Points. Fall-arrest anchorage points must be independent of any other anchorages, such as those used to support suspended platforms. They must be capable of supporting at least 5,000 pounds per employee or, alternatively, be designed and installed under the supervision of a qualified person and used as part of a system which has a safety factor of at least two.
Rigging. Personal fall-arrest systems must be rigged so that an employee cannot free fall more than 6 feet or contact a lower level. They must also limit the deceleration distance to 3.5 feet and bring an employee to a complete stop.
Impact Loading. Any fall arrest system subjected to impact loading must be immediately removed from service and may not be reused until it has been inspected by a "competent person" and determined to be suitable for use.
Rescue Considerations. One of the most frequently overlooked require-ments of the fall-arrest provisions is to assure that employees who may fall are able to rescue themselves. If they can't, arrangements must be made to provide prompt rescue services.
Is a "competent person" qualified?
The OSHA fall protection standard,like many other construction standards, uses the terms "qualified person" and "competent person." Is there a difference? You bet there is!
A "competent person," as defined by 29 CFR 126.32(f), is someone "...who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them."
A "qualified person," as defined by 29 CFR 1926.32(m) is someone "...who, by possession of a recognized degree, certificate or professional standing, or who by extensive knowledge, training and experience, has successfully demonstrated his ability to solve or resolve problems relating to the subject matter, the work, or the project."
So a "competent person" may not be qualified.
Falls are the leading cause of death among construction workers, accounting for one-third of all construction fatalities. Virtually all fall incidents can be prevented by the use of fall protection systems, such as guardrails, personal fall-arrest systems, safety nets, controlled access zones, warning line systems and hole covers.
John Rekus is an independent safety consultant and author of the National Safety Council's Complete Confined Spaces Handbook. With more than 20 years of OSHA regulatory experience, he specializes in conducting OSHA compliance surveys and providing safety seminars for workers and managers. He resides near Baltimore and may be reached at (410) 583-7954 or via his web site at http://www.jfrekus.com.