Choosing between anchor points and static lines

Fall prevention systems are a last resort in workplace safety, and they have to be done right. Wayne Fietz* clarifies the options.

As employers become increasingly aware of the legal need for safe workplaces, choosing the best anchorage systems for work done at dangerous heights doesn't get any easier.

A number of Australian companies offer anchor point and static or horizontal lifeline systems, or combinations of the two. Both systems have their advantages, and the right solution will be determined by the exact nature of the project. Presented with the facts without sales pitch, architects, builders, engineers and safety professionals can take appropriate steps to ensure the safest and most time-efficient and cost-effective solution is installed on each job.

Occupational health and safety legislation makes it important to complete a risk assessment before working at height. Under the 'duty of care' component, an employer who does not provide adequate protection for employees working above a certain height (2 m in NSW with variations in other states) could be prosecuted through civil action and/or fined for negligence.

It is a mandatory requirement that all new construction projects have safety provisions for both the construction phase, maintenance and other access after completion. For existing structures, a risk assessment can be completed to identify areas of potential hazard.

Height safety equipment should be a last resort. The easiest way to prevent the need for such measures is to design or engineer the risks out of the structure before construction begins. This can involve providing walkways, stair handrails, guards or a 1 m wall above a building's rooftop to minimise the risk of falls.

If such measures are impractical or the cost is prohibitive, a height safety solution using personal protective equipment (PPE) is required. Fall prevention systems have five key components:

• An anchorage point to which people are tethered, capable of withstanding fall arrest forces.
• A full-body harness made to Australian Standards and capable of being fitted correctly to all needing it.
• A connector linking harness to anchorage point.
• A decelerator shock-absorbing device - fitted between the harness and the anchor point - to limit fall forces on the body.
• An emergency rescue plan to ensure rescue without risk or injury to others, within a timeframe that minimises conditions such as suspension trauma.

Most large companies are familiar with these components, but there is still confusion about the correct anchorage system to use because of the array of factors to be taken into account. They include: the nature of the work and its frequency; the time required to complete it; workers' skill levels; the project budget; the design and materials of the roof or structure; the height involved; and the number of people working at the same time.

A system can be designed and rated for two main outcomes: fall arrest and fall restraint. Fall arrest systems are designed to stop a vertical fall and reduce impact on the body to a safe level. Fall restraint systems are used to prevent people from reaching places from which they could fall, or if they slip on a work platform, they are restrained from any vertical fall.

Anchor points come in many forms, but the strength requirements are the same. A single-person anchor point must be capable of withstanding a static load of 15 kN and a two-person, 22 kN.

Anchor points must be labelled with their rating and commissioning date. They require annual re-certification, with the labelling also requiring updating.

The most basic form is the single point. Connection must be made before exposure to the risk of a fall - generally meaning before leaving three-point contact with an access ladder. Great attention needs to be paid to the length of the lanyard and the fall clearance as well as the potential for a pendulum effect if the fall is at an angle to the anchor point.

Single anchors are frequently used in small locations requiring limited lateral movement. They are a cost-effective solution for locations infrequently accessed and are suitable for inexperienced users providing appropriate instruction is given beforehand. They are also minimal trip hazards and aesthetic disturbances.

The disadvantages of single anchors are that they need three-point contact before connection from below, and movement is limited to the lanyard length (a maximum of 2 m for fall arrest applications). Moving between work areas requires connection and reconnection, with the risk of being detached from the anchor points. And re-certification costs can be high on a single-unit basis.

With multiple anchor points, anchors are aligned to allow movement across and around an elevated area. Twin-tail lanyards allow connection from one anchor to another while always having one tail connected.

Experienced operators can move around safely and easily, but there is the risk of disconnection before reconnection, and hand-tool use can be restricted by the need for continual lanyard manipulation. It's also time- and labour-consuming (up to 30 per cent). Multiple anchor point applications are most suited to areas accessed very infrequently. Labelling and annual re-certifications apply to each individual anchor point, sometimes increasing costs.

For frequent work in a number of positions in an elevated site, the fixed lifeline system is best. The line has an anchor point at each end, with intermediate brackets to support its length. It can span distances and accommodate corners.

The intermediate anchors can be mounted to roof purlins, or where there is no sub-structure, to roof sheeting. Anchors may bend or roof sheeting deform to absorb the energy from a fall, and some extra training may be required to avoid unnecessary damage using this method.

The worker connects their harness through a fixed-length lanyard to a shuttle that can freely move along the lifeline. Disconnection and reconnection during work is unnecessary, movement is unrestricted and the hands are always free. The system is also simpler for inexperienced users.

The lifeline can be configured for either fall arrest or fall restraint. Ground clearance is a major consideration. Generally, with a 12 mm cable system, there is very little distortion, thus minimising fall distance and energy transfer to the system's structural components, and the chance of injury.

An 8 mm system is generally used for fall restraint applications, although it can be designed to achieve fall arrest. In fall arrest there is much greater distortion in an 8 mm system with the need for increased ground clearance.

Lifeline systems, which generally cost more to install, are either custom-designed for individual applications (when they must be individually tested and certified) or they are proprietary designs. Anchor labelling and annual inspection and re-certification still applies but is much faster and simpler.

Every employer owes a duty of care to its employees to prevent injury, or worse, death, caused by falls from height. The best method is risk assessment followed by the implementation of the most appropriate safety measures. Eliminating the risk is always preferable to having to resort to fall prevention equipment. And, if possible to achieve, fall restraint is a better solution than a requirement for fall arrest.

Wayne Fietz is the Installed Systems Manager with Capital Safety Group.