Designing a compliant Height Safety system
In accordance with AS/NZS 4488 height safety systems are to be installed on areas where persons are exposed to the risk of falling from one level to another.
This document references current regulations as to how one can successfully design and implement a system that enables personnel to access the perimeter of a rooftop area, without exposing themselves to the risk of falling – this is known in the industry as “fall restraint” and is a requirement under current legislation.
- Fall arrest – the occurrence of a person falling over the edge of a structure and an anchor point system “arresting their fall.” This method of height safety is to be used as a last resort, only when it has been demonstrated that an anchor point cannot be reasonably installed in a location that would enable the person to remain in “fall restraint.” The consequences of a fall arrest scenario can often still prove to be serious or fatal to the worker, when a rescue cannot be performed in time resulting in suspension trauma or the worker has sustained impact trauma from a pendulum swing.
- Fall restraint – the act of using a height safety system in a manner that the worker is prevented from falling in the first place. This is achieved by adjusting the length of the lanyard so that it is no longer than the distance between the anchor point and the closest fall line. The worker is then able to safely work anywhere within the diameter of the arc created by pivoting from that anchor.
- Pendulum swing – If a system is not correctly laid out or is incorrectly used, a person could swing like a pendulum in the event of a fall and slam into the side of the building – see below.
Always verify that the layout is capable of being used in fall restraint. Since there aren’t any formal qualifications, ask for specific evidence of the layout designer’s training, as well as evidence they have been doing layout work under the supervision of an experienced operative for several years.
- Hierarchy of control – used to mandate the process for selecting the most appropriate means of eliminating hazards on site.
- Suspension trauma – Suspension Trauma (also called Harness Hang Syndrome) is the loss of consciousness due to a victim being held upright with limited movement for a period of time, which can rapidly lead to death if not properly recognized and treated.
Using the Hierarchy of control:
The hierarchy of controls for safe work at height is different to the everyday hierarchy used for other hazards. Uniquely, it mandates the process for selecting the most appropriate means of eliminating hazards on site.
Work from the ground or from a solid construction such as a platform.
Use passive fall prevention equipment, like guard railing or scaffolds.
Use fall restraint/work positioning equipment, such as anchors or static lines with harness. The layout of the system is configured so that the worker can’t get to a fall edge, and therefore can’t fall. This level includes all of the procedural and training requirements so that the work is done safely.
Use a fall arrest system, so that if a worker falls their fall will be arrested before they hit the ground below. This typically encompasses the anchors and static lines under level 3, but includes rescue plans, rescue equipment, and specially trained rescue operatives.
As per this system one can identify that a fall restraint system must be installed if it is feasibly possible before resorting to fall arrest.
Designing a system that will keep a worker in fall restraint can seem complicated at first, but in reality, it is really quite simple to find out whether or not a system complies to fall restraint standards.
Simply follow these three steps to test a systems level of compliance.
- Check to ensure there is an anchor that the worker can attach themselves to immediately before mounting and dismounting the ladder or access hatch.
- Ensure that the roof anchors placed down the ridge line or roof centre (for symmetrical roofs) are spaced no wider apart than the distance from the anchor to the fall line as per the image below. Anchors may in reality have to be closer to pass the circle test in step 3.
- Ensure that all areas of the roof can be access by drawing arcs, using the distance from the anchor to the fall line as the radius of the arc. This is demonstrated in the image below. Any area outside these arcs will place the worker at consequence of fall arrest and place them at risk of a pendulum swing.
Figure 1 note the small area outside of the arcs created by the anchors in the corner can be accessed by the reach of a workers arm.
This document has introduced you to the basic concepts surrounding height safety systems requirements. It has demonstrated the difference between fall arrest and fall restraint and highlighted how you can see for yourself whether or not a system complies to the hierarchy of control.
Before choosing a height safety system for your building or structure, you can now assess the system design to see if the system is capable of keeping the worker in fall restraint and hence protect yourself from a contractor installing a non-compliant system that could have serious legal consequences for you or your business should an accident occur on the system.