7.1 Working at Heights: Fall Prevention, Fall Arrest & Rescue Systems

7.1 Working at Heights: Fall Prevention, Fall Arrest & Rescue Systems

Section 6.1 covers what the law requires of a fall protection plan. This section covers the engineering of the equipment that plan relies on: how to choose between prevention, restraint and arrest, how the parts of a personal fall arrest system work together, how much clearance they need, and how to rescue someone left hanging in a harness.

1. Choosing the Control: Prevention, Restraint, Arrest

Construction Regulation 10(4)(d) allows fall arrest equipment only where it is not reasonably practicable to use fall prevention equipment. In CR 1, fall prevention equipment includes guardrails, screens, barricades and anchorages, and also personal equipment such as a harness and lanyard used in restraint, set so the worker cannot reach the edge. The practical order of preference is:

1. Eliminate the work at height: prefabricate trusses, pipe racks and façade panels at ground level; design permanent parapets and safe maintenance access (CR 6(1)(e)–(f)).
2. Collective prevention: guardrails and toe-boards, fully decked platforms, hole covers fixed against displacement, perimeter screens, catch platforms, mobile elevating work platforms (MEWPs).
3. Personal restraint: a fixed-length lanyard or adjustable line that physically stops the worker reaching the fall edge.
4. Personal fall arrest: a harness connected to a certified anchor through an energy absorber or self-retracting lifeline, accepting that a fall will happen and stopping it safely.

2. Components of a Personal Fall Arrest System

South Africa has adopted the European standards for fall protection equipment as SANS 50xxx standards (for example SANS 50361 for full-body harnesses). The usual components are:

• Full-body harness (EN 361 / SANS 50361): fall arrest attachment points are marked "A" (dorsal, and sternal where fitted). Side D-rings on a belt are for work positioning only and must never take a fall. Waist belts are not fall arrest devices: in a fall they load the lumbar spine and abdomen and allow the wearer to slip out or invert.
• Energy-absorbing lanyard (EN 355 and EN 354): a lanyard with a tear-webbing absorber that limits the arrest force on the body to about 6 kN. The absorber extends as it works; EN 355 allows up to 1.75 m of deployment. Twin-tail ("Y") lanyards let a worker stay attached while moving past obstructions (100% tie-off).
• Self-retracting lifeline (EN 360): a device that pays out and retracts line as the worker moves and locks on rapid pay-out, giving a much shorter fall than a fixed lanyard. Check the manufacturer's stated arrest distance and whether the unit is rated for edge use.
• Anchor devices (EN 795 / SANS 50795): single-point anchors, horizontal lifelines and temporary anchors, each tested to the standard and installed to the manufacturer's instructions.
• Connectors (EN 362): self-closing, self-locking karabiners and scaffold hooks compatible with the anchor and harness.

3. Anchorages

CR 10(4)(c) requires fall arrest equipment to be securely attached to a structure or plant that is suitable and strong enough to support the equipment and anyone who could fall. In practice:

• Use only anchors designed or verified by a competent person (usually an engineer) for fall arrest loads, installed to the manufacturer's instructions and, for post-installed anchors in concrete or masonry, tested as the design specifies.
• Never anchor to guardrails, water or sprinkler pipes, cable trays, light purlins, or loose timber.
• Horizontal lifelines need engineering design: a fall near mid-span produces end loads several times the arrest force because of the cable's sag geometry, so the designer's span, pre-tension and absorber details must be followed exactly.
• Permanent anchors for future maintenance belong in the consolidated health and safety file handed to the client (CR 7(1)(e)), with their test and inspection records.

4. Total Fall Clearance

A fall arrest system only works if there is enough space below the anchor for the arrest to finish before the worker hits the ground or an obstruction. A typical calculation for a fixed 1.8 m energy-absorbing lanyard anchored at foot level uses manufacturer values such as:

$\text{TFC} = L_{\text{lanyard}} + D_{\text{absorber}} + H_{\text{worker}} + C_{\text{safety}}$

$\text{TFC} = 1.80 + 1.75 + 1.80 + 1.00 = 6.35\text{ m}$

where $L$ is the lanyard length, $D$ the maximum absorber deployment, $H$ the distance from the dorsal D-ring to the boots including harness stretch, and $C$ a safety margin. Anchoring overhead reduces the free fall and the clearance needed, so always use the figures in the equipment's instructions for the actual anchor position.

Worked example: a worker on a mezzanine 4.5 m above a concrete floor clips a 1.8 m absorber lanyard to an anchor at foot level. With about 6.35 m of clearance needed, the worker would strike the floor before the arrest is complete. Solutions, in order of preference: guardrails or a MEWP (prevention); restraint so the edge cannot be reached; or an overhead self-retracting lifeline whose stated arrest distance fits the available height.

Swing Fall

If a worker moves sideways away from the anchor and then falls, they swing like a pendulum and can strike columns, walls or the structure below, and the effective drop increases. Keep the anchor as close to directly overhead as possible, limit lateral movement (many plans set a maximum angle from the vertical, often about 30°), and use horizontal lifelines or travelling anchors where workers must cover long edges.

5. Suspension Intolerance and Rescue

A worker arrested in a harness and left hanging motionless is in danger. With the legs inactive and the harness straps compressing the thighs, blood pools in the legs, venous return falls, and the person may faint within minutes. While upright in a harness, someone who faints cannot lie down to restore blood flow to the brain, so delay can be fatal. This is why CR 10(2)(e) requires the rescue plan to be implemented immediately after a fall.

A workable rescue arrangement includes:

• Prevention of the need: prefer prevention and restraint so that suspension is unlikely.
• Self-help while waiting: harness-mounted suspension relief straps let a conscious worker stand in loops and use the leg muscles.
• Rescue equipment at the workface: pre-rigged rescue or descent kits, rescue poles, or a MEWP that can reach every place where arrest is possible.
• Trained rescuers on every shift, with practised drills for each area, so that rescue starts within minutes rather than waiting for public emergency services.

First Aid after Rescue

Older guidance told rescuers to keep a rescued person sitting upright in a "W" position for about 30 minutes for fear of "reflow syndrome". The UK Health and Safety Executive's evidence review (research report RR708, 2009) found no evidence to support this and recommended normal first aid: manage the airway and breathing, place an unconscious casualty who is breathing in the recovery position, start CPR if they are not breathing, and call emergency services. Tell the paramedics how long the person was suspended so they can monitor for complications. Follow your current first aid training provider's protocol.

6. The CHSM's Checks

Before approving fall arrest on any task, the CHS Manager confirms that prevention and restraint were genuinely not reasonably practicable (CR 10(4)(d)), that the anchor is certified and suitable (CR 10(4)(c)), that the clearance calculation works for the actual anchor position, that workers are trained and medically fit (CR 10(2)(b)–(c)), and that a rescue has been practised at that location.