Barney Green tells us how contractors should try to remove the need to work at height onsite by preassembling components prior to them being lifted.All contractors should be working to a height safety hierarchy, in order to prevent onsite accidents.
Most people recognise the hazards associated with work at height naturally, through a sense of vulnerability. They feel insecure when at height and there is a risk of falling, and they feel exposed when passing below work at height in case something falls.
For many years the normal solution to the first hazard, was to issue a harness and lanyard (frequently with no training in its use), and for the second hazard, to cordon off the area below the work.
There has been a long established safety hierarchy which identifies the best route to follow when solving safety problems – avoid, prevent, and then mitigate. This hierarchy has now been broken into nine easy steps, to assist the selection of the best solution to any work at height problem.
First and foremost, we should still avoid the need to work at height. We should try and find another way of carryout out the work. One example would be to preassemble components prior to them being lifted (see pics below), and to modularise the construction process. Any action, or work sequence, that removes the need for some work at height, is of primary safety benefit to any construction project.
Having said that, we must recognise that avoidance is not always possible, and that some work at height may be necessary. At this point we should also recognise that measures, which offer protection to all, are better than measures which protect an individual, and also that measures which offer protection without the need to act, are better than those that require some action to be protected. We are therefore looking for collective passive safety. This is the next level in the work at height hierarchy, and the subsequent route through the hierarchy is best shown as a matrix.
On the left of the matrix we have the four levels of protection, prevention, minimising height and consequence, minimising consequence, and doing nothing. We have two columns within the matrix, collective measures, and personal measures. We then follow down the matrix, zigzagging between the collective and personal columns, as shown.
Examples of preventative measures that offer collective protection would include edge protection systems, advanced guardrails, and working platforms. If not suitable, we can move to preventative measures that protected only a single person, such as alsipercha, pulpit steps etc.If we cannot avoid the need to work at height, and we cannot prevent falls, we should then minimise the height and consequence of any fall. In the collective column we should be looking at safety nets and other soft landing systems, as these gather the faller, or falling material, into them and they slow down and stop the fall event with minimal chance of injury. If we cannot use collective measures, we move to the personal column and can now reach for the harness and lanyard solution of old (personal fall protective equipment or PFPE).
When specifying the use of PFPE, it is important to consider all aspects of the work sequence and the equipment needed, from the anchor point to the worker. Many accidents in the past have resulted from poorly or incompletely specified solutions, when the worker has been left to choose their lanyard and their anchor.
The general rule of thumb is to use as short a lanyard as possible, and to anchor above and behind the worker. Bear in mind that, to safely resist the fall load, an anchor point should be capable of supporting a small car. Also remember that the energy absorber can increase the lanyard length by 1.75m if fully deployed, and this can lead to clearance distances of over 6m below the anchor point being required.
It is extremely important to consider the need for immediate rescue when using PFPE. The fall event will frequently lead to significant injury, and once arrested, a faller needs attention before the potentially fatal effects of suspension trauma set in. This will often lead to the need for complex equipment and highly trained rescuers to be available, on site, in case they are needed. This adds to the cost, and reduces the effectiveness of PFPE based solutions.
Once we have considered these top five layers within the hierarchy, we are starting to move to less effective equipment. The final four levels in the hierarchy all offer some form of protection, but in the vast majority of cases they can be improved upon, by revisiting the layers above.
At one point there was the suggestion that ladders should be banned from construction sites, as they offered no real protection from the fall hazard and they are for single person use only (personal). As you can see they appear in the hierarchy, but they lie within the very bottom category. There are applications for which a ladder can be defended as offering the best solution, but only once the decision maker has moved steadily through the hierarchy and carefully considered and rejected all the other solution types.
The most common hazards associated with work at height (falls and falling objects), can be risk managed from the first five levels in the majority of situations.
If you are unable to find a solution to your work at height problem within these top five levels, perhaps some professional advice should be sought before moving further down the hierarchy.
Barney Green is a lapsed civil engineer having done 10 years of study, site, and design work, before specialising first in construction fixings and then in securing those who work at height. Green spent 20 years as a height safety systems installation contractor, installing anchor points, cable systems, safety nets, edge protection, and temporary stairways. He has spent the last five years with systems manufacturer, Combisafe International.
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