Choosing and using mobile access platforms
06 August 2009
The latest statistics from the HSE show that 58 people were killed as a result of falls from height during 2007/8. A further 3235 people suffered major injuries through similar accidents. This means that working at height continues to be the biggest cause of workplace deaths and one of the main causes of major injury.
Choosing and using mobile access platforms
The figures also show that reductions in both achieved in the preceding decade have more or less levelled out in the past four years. The long term trend may be downwards but there
The latest statistics from the HSE show that 58 people were killed as a result of falls from height during 2007/8. A further 3235 people suffered major injuries through similar accidents. This means that working at height continues to be the biggest cause of workplace deaths and one of the main causes of major injury. The figures also show that reductions in both achieved in the preceding decade have more or less levelled out in the past four years. The long term trend may be downwards but there is still much more to do to reduce the risks associated with working at height.The HSE recommends, through the Working at Height Regulations 2005, that working at height should be avoided wherever possible. In many industries, including construction, maintenance, cleaning and arboriculture, it is not possible to eliminate working at height and the emphasis has to be on reducing risk and developing the safest and most effective practices. Selecting the best equipment, providing staff with proper training and adopting a work culture of care and vigilance should be uppermost in everyone's thoughts.
One of the most popular options in recent years has been to use a mobile access platform mounted on a light commercial vehicle. Platforms like these are affordable to purchase and can be driven on a normal driving licence, unlike larger and specialist vehicles which require advanced or HGV licences. They are also attractive for hire companies because the initial purchase cost allows them to be hired out at a daily rate within the pocket of many small businesses while offering a decent rental return over a sensible working lifetime.
The Working at Height Regulations 2005 include some very specific requirements for the use of access equipment. While these rules are common to all types of access equipment, not all mobile access platforms are the same.
Advances in design and technology mean that the latest LCV mounted access platforms offer maximum working heights of up to 21m. These can be used to access the external walls and roofs of buildings up to three or four storeys high which makes them ideal for many construction and maintenance tasks. Even at these heights, and with outreaches up to 10m, platforms like these are powerful enough to support a basket with two average sized people and their tools.
The boom should be strong and rigid to provide a stable and safe working platform and, ideally, hydraulic and electrical services should be housed internally to reduce the risk of accidental damage to critical components.
Safety features of the access platform are an important consideration. For safe working the unit has to be positioned on surfaces which are hard enough to support the vehicle and load. Outriggers are often incorporated into the chassis to provide additional stability and to allow the vehicle stand level. It should not be possible to operate the platform until these outriggers are deployed properly.
Many LCV-mounted access platforms are designed to operate in temporary locations where other activities are taking place. They typically have mechanisms that are compact enough to fit onto the vehicle but an important consideration is what happens when the boom and platform are extended or when the mechanism is rotating. The best designs should have what is known as zero tail-swing. In other words, at no time should any moving parts extend beyond the footprint of the vehicle and its outriggers at ground level. This helps to ensure that bystanders and other machinery in the vicinity have reduced risk of sudden or unexpected contact with the platform mechanism for the best possible safety.
Once the boom and platform are extended and in use one of the main concerns is overloading. This is a complex subject because the maximum safe working load will vary depending on the actual load in combination with factors such as boom extension, elevation and outreach. The best equipment will remain within a safe working envelope determined during development and testing of the platform. When these parameters are exceeded the mechanism should lock out further excesses and only operate to bring the boom and platform back to within normal safe operations. Devices which simply lower the entire boom and platform assembly to the ground if loadings are exceeded should be avoided. This action may appear to be a sensible failsafe precaution but if the automatic and unexpected lowering of the assembly places the occupants of the basket or bystanders who may be underneath at any risk it is not a good idea.
Any equipment designed to operate at height should incorporate a manual override so that the boom and basket can be operated in the event of power failure. Ideally this will allow the equipment to be fully retracted in a controlled and manageable fashion. This may be slower than simply opening a hydraulic non-return valve to lower the boom but it is far safer to control the movement of the boom and load in this way at all times.
The design of the basket is critical to safe working at height. The maximum working load should be sufficient to support the worker and their equipment or tools. It should also afford easy access to the working area so long as the very stringent rules about safety guard rails, perimeter toe rails and platform non-slip surfaces are maintained. It should be possible to activate the boom and basket position using controls in the basket or at ground level, but not at the same time as this can be potentially dangerous because conflicting control messages could be sent.
The best access platforms will offer maximum working loads of to around 200kg, often enough for two average sized men and a supply of tools or equipment. Space for two people is ideal because it offers a decent working area which means the boom and basket need to be repositioned less frequently for better overall working time and productivity. Dual working also gives hire companies the option of supplying the vehicle on an operated hire basis, where the operator accompanies the worker to control and manoeuvre the boom and basket.
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