Soft Landing Fall Arrest Systems
WILL THE FALL PROTECTION SYSTEM YOU EMPLOY TRULY PROTECT YOUR WORKERS?
I have been asked several times over recent months what comprises a soft landing fall arrest system.
Simply, these types of systems minimize the impact forces on a body by absorbing energy of falling person.
Extensive research has been carried out in Europe (1) in consideration of the best way of preventing or reducing injury where the person suffers a fall. Research and testing considered and compared various options including a boarded deck, safety harnesses and safety net systems, and after extensive testing concluded that safety net assemblies are far more likely to prevent or reduce injury than the other options considered.
(1) BECKER,K., LOMBART,H et al Optimisation. Of intercepting devices – Biomechanical stress limits of humans. Bochum, Germany
The authors of this comprehensive report concluded that the main purpose of any fall arrest system is to reduce the forces on the body suffering a fall such that the likelihood of injury is reduced to a minimum. With regard to safety net systems, the mechanics of such an approach require that:
- The net assembly i.e. the net the ties the anchors on the supporting framework progressively deflects on the load, absorbing most of the energy of a fall, so that the remaining forces on the body will be unlikely to cause injury;
- The net assembly is able to progressively deformed or deflect so that the falling energy can be safely absorbed;
- This absorption can be the sum total of the energy absorbed by the nets, ties, border ropes, anchors and supporting frameworks;
- The net and net assembly are free to deflect and realign to the best able to absorb the impact energy of falling body; and
- Sufficient mesh cords are available within the net, of which the combined tensile strength and ability to deform sufficient with stand the design impact. This combined strength is not so high of them make them that too stiff or rigid so as to cause injury to a falling person.
There have been a number of proprietary solid work platforms being promoted over recent months as a means of providing fall protection solutions for workers on construction sites . Clearly solid work platform systems do not provide the level of energy absorption referred to above, and therefore cannot be considered to provide a soft-landing protection system. If a solid work platform system is used to provide access to enable builders to stand trusses in a residential build for example, the platforms will then be left in place as “fall protection” for the roofers who could still be working at a height of over 2m above the platform level (i.e from ridge line) when they come to site to carry out their works. This is no different from someone working at the level of the top plate, with no protection to prevent a fall to the slab 2m below.
If consideration is then given to the inconvenience that solid work platforms create i.e unable to work in rooms where the platforms have been established ( works can carry on. both above and below safety net systems); the time taken to establish the platform system and also the fact that very rarely does the platform module fit exactly in rooms thereby requiring overlapping platform tiles that create trip hazards, it is easy to see why safety nets provide a more popular solution, whilst also protecting workers by establishing a true soft landing fall arrest solution.
As a matter of interest there is currently a Safety Alert on the homepage of the FASET website that outlines the dangers of mixing components of solid working platform systems, which is further cause for concern.
So when thinking about how best to protect your workforce, ask yourself whether or not the fall arrest solution in question is the best for the situation at hand, and if it will minimise the impact of harmful forces experienced by a body as a result of having it’s fall arrested by the system being considered .
Until next time