Fall Protection Anchorages - The Basics
Whether you’re an architect, an engineer, or a contractor, you are inevitably going to come across a project where someone asks if an active fall protection system might be an acceptable solution. With this article, I want to concentrate on some of the basics for anchorages, which are one of the most critical components of any such system.
This post is focused on single point, single user anchorages in general industry, where active systems have been gaining popularity and have recently been directly incorporated into OSHA’s general industry regulations. I am hopeful that this article will be valuable in starting to tackle that “how about a fall protection system” question next time it arises.
Note that all active systems should be designed and implemented under the direction of a qualified person and that although some of the basic principles herein may be universal, special consideration should be made for systems which do not fall under the scope of this article. These systems might include, but are not limited to, those in the construction industry, those utilized for suspended maintenance and window cleaning, horizontal lifeline system anchorages, confined space or rescue systems, and for multiple user systems.
What is a Personal Fall Arrest System?
A personal fall arrest system, or PFAS, is defined in ANSI Z359 as “an assembly of components and subsystems used to arrest a person in a free fall.” A typical PFAS might collectively consist of an anchorage, an anchorage connector, a lifeline or lanyard with integral energy absorption capabilities, and a full body harness. The anchorage should be certified by a qualified person. All other components should be ANSI compliant and certified by a qualified person to compatibly perform the intended function when used collectively.
An active system is defined in ANSI Z359 as “a fall protection system that requires authorized persons to wear or use fall protection equipment and that requires fall protection training.” Fall restraint systems, which prevent the user from reaching the hazard, and personal fall arrest systems, which stop the fall of the user in the event of a fall, should be considered active systems.
If you need to don a full body harness and the fall from height hazard is not protected by conventional passive means, such as a guardrail or barrier, then you are most likely staring at an active system, and it should be respected as such.
What is an Anchorage?
Anchorage – OSHA Definition: “Anchorage means a secure point of attachment for equipment such as lifelines, lanyards or deceleration devices.”
Anchorage – ANSI Z359 Definition: “A secure connecting point or a terminating component of a fall protection system or rescue system capable of safely supporting the impact forces applied by a fall protection system or anchorage subsystem.”
Anchorage Connector – ANSI Z359 Definition: “A component or subsystem that functions as an interface between the anchorage and a fall protection, work positioning, rope access or rescue system for the purpose of coupling the system to the anchorage.”
Interpretation of the definitions above suggests that the “Anchorage” is the base structure to which a system terminates and is ultimately the last line of defense in resisting the forces developed should a fall incident occur.
That’s fair on a technical basis. However, as active systems have become more commonplace in general industry, it is typically assumed in real-world practice that the terms “anchorage” or “anchor point” or “tie off point” consist of everything above the lifeline’s snaphook or carabiner connector.
Think about it. It would be of little value to the end user or client for an engineer to declare that a specific structural element is of adequate strength to serve as an anchorage without also specifying a compatible anchorage connector and how it should be secured to the base structure. Some typical anchorage connectors might be pre-engineered, commercially available and ANSI certified D-ring or d-bolts, beam trolleys, web tie-off adapters, or custom steel bent bar and pipe fabrications.
A typical anchorage consultation provided by Mainstay would consist of verification that the base structure is adequate to support a fall protection load (Anchorage), design and specification of the anchorage connector and its connection to the base structure, and design of any modifications to the base structure (anchorage) that might be required to accept the anchorage connector or to support the fall protection load. We would also verify that there are adequate fall clearances, an absence of swing fall hazards and evaluate the hazard for alternatives means of hazard control which do not require an active system. More on that below.
Is an “Anchor Point” the Best Solution?
Incorporating an active fall protection system is often the quickest and least intrusive means of controlling a fall from height hazard and at the lowest upfront cost. But, that doesn’t necessarily make it right.
It should be remembered and reinforced that “active” systems inherently remain heavily reliant upon the user and their training. The implications of misusing or abusing the system, whether intentional or not, or even worse, neglecting to use the system at all, is outright dangerous.
Even if used properly, active systems are effective reducers but do not eliminate all risk to the user. Should an incident occur, and if an active system performs as anticipated to prevent a catastrophic incident, it might still be expected that the user would still experience some degree of trauma, albeit better than a 20’-0” free fall. On top of that, rescue plans are critical and often overlooked. OSHA has published that prolonged suspension in a fall arrest system can result in unconsciousness, followed by death, in less than 30 minutes. Other studies wave the white flag at under 15 minutes.
We should also consider that a fall protection system must be actively managed by the owner – annual inspections, equipment and device maintenance and replacement, developing work procedures, maintaining user training, performance audits, and inspections, etc. – and that such systems might influence an owner’s worker’s compensation or insurance premiums. Do the upfront cost savings really pass the sniff test?
Don’t get me wrong, active fall protection systems are an immensely valuable tool in general industry and in many cases, might be the only means of risk control in order to prevent a catastrophic incident or to perform critical preventative maintenance that has been neglected. But, they’re not even close to optimal if they can be reasonably and feasibly avoided. Active systems should be considered as a last resort only after the following fall from height hazard elimination and control methods have been exhausted:
Elimination or Substitution: Remove the hazard and/or the hazardous practice. Engineer it out. An example might to be to relocate an overhead mechanism to near ground level. This is the most effective control measure, and it nearly eliminates the human factor. The greatest reduction of risk will be realized.
Passive Fall Protection: Isolate or separate the hazard and/or the hazardous practice from workers with a physical barrier. Examples of passive protection include guardrails, load rated floor hole/opening covers, and rooftop designated areas. Common, recognizable and effective.
Fall Restraint: A system which secures users to an anchorage using a lanyard that is short enough to prevent their center of gravity from reaching the fall hazard. Generally preferable over fall arrest systems. However, their utilization is limited to secure walking-working surfaces, and they might become difficult to manage over an extended period of time in general industry.
The 5,000 Pound Rule….
Most of us are familiar with the 5,000-pound rule. Hanging a small truck from the existing structure is the first thing that comes to mind when designating a fall protection anchorage. I’m not going to get into a physics dissertation here; it is what it is. A 5,000 pounds equivalent static force, figure it out! Or not….
Did you know that you won’t be able to find a conventional ANSI approved lifeline that has a maximum arresting force over 1,800 pounds? And that some might be designed to 900 pounds? And did you know that OSHA permits certified systems to be utilized on anchorages that are capable of supporting these loads at a factor of safety equal to 2.0?
That’s right. As long as the complete personal fall arrest system is designed, installed and used under the supervision of a qualified person you might be able to designate an anchorage rated for 3,600 pounds, or even 1,800 pounds, instead of 5,000 pounds. Remember this, because it will get you out of a jam in the future. The equipment is ahead of the curve.
With expertise in both structural engineering and fall protection systems, Mainstay has been able to utilize this clause in the regulations to implement compliant and safe fall protection systems where the existing structure might not be capable of supporting a 5,000 Anchorage. As an example, it is generally difficult to certify a steel open web bar joist for 5,000 pounds, but it might be feasible if a fall protection system can be implemented that limits fall arrest forces to 900 pounds (1,800-pound anchorage) or 1,800 pounds (3,600-pound anchorage), as long as the complete personal fall arrest system is known of course.
Overhead Anchorages….
These are my favorite. They typically consist of an anchorage at the overhead structure and a self-retracting lifeline that remains in place with a rope tagline that is utilized by the user to retrieve the snaphook or carabiner connector. Cheap, simple, and as close to abuse-proof as you’re going to find in active fall protection. Couple that with an owner who has a strong safety management program and it can be downright effective.
Some basic principles to keep in mind:
The most efficient location for an overhead anchorage is typically directly above the fall hazard.
The higher an anchorage is above the user, the better. Anchorages located below the users dorsal D-ring will increase total fall distances. Feasible inspection of the system should also be considered.
The safe working zone for an overhead anchorage is typically cone shaped and emanates from a vertex at the anchorage. The safely accessible area at the walking-working surface will consist of a circle with a radius that is mostly dependent upon the available fall clearances and the height of the anchorage. Increased available fall clearances and a higher anchorage will result in a larger safe working zone.
Shock absorbing lanyards are essentially antiquated in general industry and should never be considered when available fall clearances are less than 15’-0”. Self-retracting lifelines are amazing tools, and if used properly with an optimal layout can be effective when available fall clearances are as low as 6’-0”.
Be cautious of obstructions in the fall path, such as piping and equipment at ground level. A user should not strike obstructions before the fall is arrested. These elements should be considered in determining available fall clearances.
Be wary of surprises which might reduce available fall clearances, such as fork lifts and pedestrians or other workers who might be in the area below.
Be wary of swing fall hazards. The rules of physics mandate that under ideal conditions a user will pendulum back and forth until coming to rest directly beneath the anchorage. Anything that might be in the path of the user while this plays out could be a hazard. See rooftop anchorage basic principles for what I believe to be a decent narrative description of a swing fall hazard.
Consider the anchorage location in relation to the user’s task. Ideally, the anchorage would be located directly over top of or behind the user’s dorsal D-ring. If the anchorage were located in front of the user, their lifeline might be a nuisance as it is rides over their shoulder or scrapes against their hardhat. This phenomenon is exaggerated as the height of the anchorage is reduced, and could be detrimental if the task involves intricate manual operations or handling of hot or otherwise dangerous material.
Rooftop Anchorages….
We’ve all seen them, and they typically consist of a steel pipe post with a bent u-bar or eye at the cap plate for attachment of the subsystem. They are an acceptable form of protection in general industry for work that is performed on low slope roofs and quite effective if used properly and dedicated to a specific point of access. In general, they are more prone to abuse by untrained users than overhead anchorages.
Some basic principles to keep in mind:
Users must be able to safely access the anchorage to connect their fall protection system without being exposed to a fall hazard.
Because rooftop anchorages are typically located near foot level of the user, an additional inline energy absorber might be required as part of the complete personal fall arrest system.
The total fall distance of a user is also greater with anchorages located near foot level. With optimal layout, active systems might be feasible when available fall clearances are as low as 16’-0. To be certain, caution should be exercised when available fall clearances are under 20’-0”. Optimal conditions might consist of the user working near the leading edge directly perpendicular to the anchorage; any horizontal movement from perpendicular to the anchorage will increase the total fall distance.
Be cautious of obstructions in the fall path, such as trees, utility racks, canopies and equipment at ground level. A user should not strike an obstruction before the fall is arrested.
Be wary of surprises which might reduce available fall clearances, such as trucks at a loading dock.
Be wary of swing fall hazards. Let’s perform an exercise. Grab your pencil and draw an L-shaped building. Now, in your head, picture an anchorage located at the inside corner of that L-shaped building’s roof. Draw an “x.” Now picture this: a user connects their fall protection system to the anchorage, walks 20’-0” along one of the roof edges………and then falls. This is where physics comes into play…. The user’s fall protection system engages, and his body wants to swing like a pendulum back and forth until it comes to rest directly perpendicular to the anchorage. Guess what happens before this is able to play out? His body slams into the other projecting wall of the L-shaped building! This is a classic swing fall hazard.
Consider rescue. An active fall protection system is rendered useless if a user cannot be promptly rescued should an incident occur. A rescue plan should be developed in unison with any active system. Is the area of the roof accessible by emergency responders? Who are the emergency responders, what equipment do they have and what are their capabilities?