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Twin tail fall arrest lanyards

Purpose
Background
Recommendations
Further information

Purpose

 

To alert workers, principal contractors, employers, self-employed persons and suppliers of the risk of failure of twin tail fall arrest lanyards. To highlight design issues that should be addressed to minimise this risk.

This alert replaces another alert, 'Twin tail fall arrest lanyards (interim advice)' issued on 25 November 2004.

Background

In November 2004 a worker received fatal injuries as a result of falling from a transmission tower near Toowoomba. The worker was using a twin tail fall arrest lanyard and the lanyard failed when he fell from the tower.

Workplace Health and Safety Queensland (WHSQ) is currently investigating the incident. The investigation has highlighted important factors that must be considered in the design of twin tail fall arrest lanyards.

A twin tail lanyard, of the type involved in the incident, consists of two lanyard tails that are attached to one end of an energy absorber. The other end of the energy absorber is intended for attachment to a fall arrest harness. An example of this type of twin tail lanyard can be seen in figure 1.

Figure 1 – a twin tail fall arrest lanyard and the location of its webbing loop
Figure 1 – twin tail fall arrest lanyard

The attachment loop between the energy absorber and lanyard tails consists of webbing that is stitched back onto itself to form a loop. When a fall arrest load is applied to the lanyard assembly, such that the load is in line with the energy absorber body, the loop should transfer load without failing. This type of loading is illustrated in diagram 1. However, in some fall arrest situations a side load can be applied to the loop and this load will tend to rip the stitching on the loop apart. Pure side loading is illustrated in diagram 2.

 

Diagram 1 - illustration of two opposing forces (load) applied in line with the energy absorber body of the lanyard
Diagram 1

Diagram 2 - applying a pure side load to the webbing loop of the lanyard
Diagram 2

A side load can be applied to the connecting loop if the user falls from a structure with the lanyard assembly used in either of the following two ways:

Recommendations

Twin tail fall arrest lanyards should be designed so that no part of the lanyard assembly can catastrophically fail if the user falls from an elevated area with the lanyard assembly attached in either of the following two ways:

Designers, manufacturers and suppliers should all ensure that measures have been undertaken to verify that catastrophic failure of the lanyard assembly, in the two ways highlighted above, will not occur. The most suitable means of verification is by testing the lanyard assemblies. Any testing should replicate the potential type of loading discussed in this alert and the guidance of competent persons should be obtained.

If written verification cannot be supplied, the twin tail lanyard assembly should not be used.

Further information

Further information can be found in the Australian/New Zealand Standard AS/NZS 1891.1 Industrial fall-arrest systems and devices - Safety belts and harnesses (non-Queensland Government link).

For more information contact Workplace Health and Safety Queensland:

Phone 1300 369 915
Internet www.worksafe.qld.gov.au

Notes:

1 It is also conceivable that side loading may be applied to the connector loop in the event of a fall when moving vertically up or down a structure. However, loadings in horizontal applications are likely to be more severe.

 

2 WHSQ and manufacturers do not approve of nor encourage connecting a lanyard tail to the side connection point. However, it is considered to be unrealistic to expect all users to be fully aware of the risks involved with this practice (i.e. that total failure of the lanyard can occur).