Working at height has been a leading cause of serious and fatal accidents for many years. It is essentially impossible to eliminate the need to work at height, so focus and emphasis needs to be placed on managing this risk.
Working at height does not mean you have to be above the ground. The definition of what constitutes working at height was changed to include scenarios where someone is working at ground level but next to an excavation or a drop in level. So you can fall from the ground to a lower level, this is also considered to be working at height.
The notion that working at less than 1.8 meters (or 6 feet) is safe and does not require any special precautions is not correct. This was a historical detail that used to be enshrined in some former legislation. It was based on the idea that if a person fell less than 6 feet then the consequences were less likely to be fatal or serious. So even if statistically this is true, it begs the question of how many serious or fatal accidents are acceptable? The answer of course has to be “none”. I can recall investigating a fatal accident to an electrician who was working on a doorstep, so no more than 20 to 30 cm above ground level, he tripped and fell, struck his head and unfortunately passed away. The point of this case is not to say that I would have expected to see edge protection when working on a doorstep, it is rather to dispel the notion that there is such a thing as a safe height to work at. The truth is working at any height carries a risk and therefore detailed risk assessment is a critical part when planning to work at height.
There can be a further complicating factor in identifying risk and that is that the person may not appreciate that they are working at height. I can recall several investigations where people went to conduct a short task on a roof, they were not near the edge of the roof and did not perceive that they were in any danger. However, as we all know, there can be hidden dangers with fragile rooves. The classic case is the asbestos cement roof, very popular and common on industrial buildings. These roofs were often painted or coated especially as they got older and so it was not always possible to tell that they were asbestos cement. The biggest problem with these roofs is that the material becomes very brittle when exposed to sunlight and the constant cycle of weather. Unfortunately, many workers would step on the roof surface thinking it was strong and weight bearing and then fall through as the brittle material fractured. I also came across other cases where the workers were concerned about the roof but thought it would be okay as long as they walked along the bolt line (which usually had a structural beam underneath), but of course if someone stumbled or strayed off the line, again they would come crashing through.
“working at any height carries a risk and therefore detailed risk assessment is a critical part when planning to work at height”
Questions of Safety
Clearly there are many things to consider when planning to work at height; at what height will you be working; how long is the job likely to last (expected duration), will you need to handle materials while you are at height, will you need to use hand tools or power tools; how many people will work at height, just you or colleagues?
These questions form the basis of the information that you need to develop your risk assessment. There are a multitude of different solutions to working at height; ladder, step ladder, scaffold, tower scaffold, cherry picker, elevated mobile working platform, scissors lift, work basket (forklift or crane supported). Then of course there are scenarios where you don’t need a platform, but you might need PPE to keep you from falling; harnesses, lifelines, reel belts, running lines. In recent years, there has also been an increase in the use of abseiling to safely work at height. All of these solutions have merit, the key though is to select the most effective solution for the work at hand.
You may find that the decision has been made for you, as your first consideration must always be what does the local national and/or regional legislation demand that I do? Some countries have very prescriptive legislation that tells you exactly which solution you must use. But this is less and less common these days with most countries adopting a risk-based approach and it is this approach that we will now focus on.
Let’s go back to our questions and see how they influence our decision making. First we consider at what height are we going to be working, or looking at it the other way, how far might we fall? We will consider that the higher we are the greater the risk of serious injury, and therefore the increase in protection we may need.
Safety, illustrated
Let’s take a simple example to illustrate this, suppose we have to change one light bulb, we would be approximately 75cm above the ground. You might decide to use a stepladder or you could use a simple tower scaffold platform. Potentially it might be quicker and easier to use the stepladder, so what other factors might influence your decision? One might be duration, if you only need to replace one single bulb and the job is only going to take 1 or 2 minutes, then the stepladder is a perfectly satisfactory solution. However, if you have hundreds of bulbs to replace and some of the bulbs are fluorescent tubes then the stepladder probably would not be so good and then the small tower scaffold (work platform) would be much more effective.
If you had one bulb to replace but it was 5m above the ground, then a ladder solution would likely not work and at that height a work platform; be it a tower scaffold, cherry picker or MEWP would be much more effective.
So the height at which you are working and the duration of the job are key considerations, but you also need to consider what you are going to do when you get there. If the job details using a small hand tool like a screwdriver and it is a short duration job, and less than 2 metres above the ground, then a ladder solution may be considered satisfactory. There are no definitive rules about what types of hand tools can be safely used of a ladder, but suffice to say that the heavier the tools (hammer, saw, etc) then the more significant the risk and the likelihood that you would have to consider a platform solution instead. If you have to use both hands for the task that would negate the use of a ladder. So if you need a hammer and chisel or if you need to hold an item in one hand and saw it with the other that would be a task for a safe work platform and not a ladder. As soon as you start to use power tools, you should use a work platform and not a ladder.
The scenario where a person is working on a roof can be more complex but equally offers more options. If the work is on a flat concrete roof, which can be accessed internally through the building (fire escape for example) then erecting edge protection around the edge of the roof may be an option. For short duration work, wearing a harness and restraint line that prevents the person accessing the edge may also be appropriate. If the roof is fragile (asbestos cement or roof panels) then either the surface of the roof would have to be covered with scaffolding access ways or if the work involves removing or replacing the roof then the scaffolding could be ‘birdcage’ style inside the building and underneath the roof. Where the roof is pitched or where the roof cannot be accessed from inside, then some form of access scaffold would be more appropriate. For smaller single location work, e.g. working on a chimney, then a tower scaffold may be fine, for a job that involves retiling the entire roof, then a wraparound scaffold providing full safe access to all areas would be more effective.
If there is unrestricted access around the building then the roof or higher elevations could be safely reached by a scissors lift or cherry picker that can be moved around the building. If access is limited then a cherry picker may be helpful as the basket can be moved horizontally to provide greater reach.
Alternative solutions
As I mentioned there are a very large range of different solutions, I wanted to summarise a few other options; For steel erection a cherry picker can now be a useful option. For buildings that have a repetitive need for rooftop or window cleaning and maintenance, the building can be designed with a so-called “Running Line”, a fixed permanent steel line, where workers can clip on with a safety harness. This allows them to move freely around the building to carry out maintenance / inspection tasks. I also referenced the use of abseiling as a safe access technique. This can be a useful technique where a small repair has to be made to a window or cladding on a tall building where it would be difficult or uneconomic to install a scaffold from the ground. So abseiling allows the worker(s) to safely access the location and be free to use both hands to conduct the work. There are two major considerations here; one is the prevention of dropped objects and the other is the ability to rescue an abseiling worker if he is stuck or is injured. It invariably means that two completely independent lines must be installed; even if it is planned, that only one person will be working. This is similar in nature to the role of a standby diver in marine operations. Dropped objects prevention would warrant an entire article on their own, so I will not go into too much detail here. There is an excellent website set up by the DROPS organisation which provides access to a great recommended practise which is free to download for all. It provides guidance and information across a great many dropped object concerns.
I am often asked if people working on scaffolds or in cherry pickers (baskets generally) need to wear safety harnesses? The simple but unhelpful answer is “Sometimes”. So lets explore this; in general a scaffold should be designed and built so that it provides a safe working platform without the need to wear a harness. It can be unhelpful in some trades that have to move around a scaffold to keep clipping and unclipping. In some countries and in many recommended practises it is specified that scaffold erectors should wear a harness when they are building/ dismantling the scaffold.
With cherry pickers and baskets, the preference is for occupants to wear a harness; they don’t need to move around that much so it does not get in the way. It is unlikely that they would fall out, but I have seen instances where people are leaning or stretching from the basket to reach something, then the harness provides that extra layer of protection. Similarly on scissors lifts and MEWPs.
“there are two major considerations here; one is the prevention of dropped objects and the other is the ability to rescue an abseiling worker if injured”
A word of caution on the use of harnesses, there are a number of important considerations to address before using one. There has to be a safe location to clip the harness line into, it has be capable of supporting the weight of a falling person, it either has to be specifically designed and engineered (permanent anchor point) or for a temporary anchor point it must be inspected and tested and confirmed as safe to use by a technical specialist. The anchor point has to be in a location where it will afford maximum protection, ideally above the worker or at the very least at chest / head level. Anchor points that are below the feet of the worker are not effective as the worker will fall some considerable distance before the restraint kicks in, which could result in injuries caused by the harness or the worker may strike other objects as they fall? If you are going to use a harness in any capacity, your risk assessment must also consider how you will rescue and recover someone if they fall. This is not as easy as it sounds. You need to consider how you will safely recover the person to a place of safety. It will not be possible to for one person to pull on the lanyard and recover the person back to the work platform and there may not be space for two or more people, so alternative and possible even mechanical solutions must be considered. Whatever solution is selected it must be clearly defined in the risk assessment / safe system of work or method statement.
Training
Of course, all of the above must be underpinned by training and competence. People who are required to work at height and supervise work at height must be fully trained in the different techniques that they will be required to use. The training can take many forms as there are many different organisations around the world providing such training, some large organisations can provide internal training and some training may even be provided “on the job” by a competent supervisor. The essence for the company is to ensure that the worker is competent to carry out the specified work.
In addition to training, the people working at height should be familiar and engaged in the risk assessment process. There should be a daily or shift pre-job safety meeting (in some industries known as a toolbox talk) to discuss the work tasks and the risk controls in place for each stage. If the work sequence changes or if the conditions change, then work should be stopped and a further meeting conducted to review the risk assessment and make any amendments required to safely carry on. A final check should be made to ensure that all equipment is in good condition, inspected and certified (where required) and fully functioning.