Whilst power access platforms are designed to be strong and stable on a wide range of floors and spaces, whether on or offsite, the most common type of accident involving powered access platforms is still overturning. With due care and attention these dangerous and expensive incidents may be avoided. There are two main factors which can prevent stability problems: a basic understanding of stabilising equipment properly and carefully assessing the surface they are used on.
Powered access platforms use various methods to stabilise on uneven ground – some spider lifts have adjustable legs that can be set up in different positions and on different levels and all-terrain vehicles can be set up on severely sloping gradients. Here are some key points to remember:
• Each machine has benefits and limitations so familiarise yourself with the specifics and only operate the machine within the manufacturer’s recommendations
• Inspect the machinery to make sure it is fit for use and ensure operators are fully trained
• Warning lights on the control panel will tell the operator if the machine is not level
• Outriggers generate high pressure at the feet which may not be supported by many areas of soil or unmade ground and even some paved areas, so additional foundations may be required
Ground conditions have a big impact on the stability of MEWPs and a ground survey should be completed before every job. The ground may settle when subjected to the loads of MEWP wheels or outriggers. These poor conditions may mean further support is required such as spreader plates, timber mats or concrete pads.
Ground condition assessment is also important for self propelled MWEPs such as booms and scissor lifts which may be driven along the ground with the platform raised. Moving from hard ground to soft may cause instability and overturn.
Level indicators provided on the MEWPs should be constantly monitored by the operator. If warnings are given when safe operating limits are exceeded, the platform should be lowered and the MEWP reset in a level position.
Spider platforms with outriggers should also be regularly checked for machine level especially if suspected that spreaders or mats may be sinking.
Prior to using a high access MEWP a visual inspection and assessment of ground conditions are often adequate (as opposed to having a full geotechnical survey). This assessment must be made by a person with the knowledge and experience to know if further expert advice is needed.
When checking the ground look out for these typical hazards…
• Uncompacted Fill – look for backfilled trenches and any cracking along the line of the trench
• Proximity to Excavations – If the MEWP needs to be used close to the edge of trenches or excavations where the outriggers or wheels may be in the “danger area”, then an engineering assessment must be made by a competent geotechnical engineer before the MEWP is set up and operated.
• Floors, Cellars, and Basements – Check the load bearing. Many floors are unable to take the weight of a MEWP and could collapse without warning. If in doubt get a geotechnical engineering assessment made.
• Paved Areas – May look strong but could have been laid on weak ground. Look for cracks and uneven slabs. Footpaths should be considered suspect and carefully checked.
• Underground Services – The weight of a MEWP may cause damage to sewers, drains, manholes and gas and water mains. Use caution.
• Weather Conditions – Regular checks need to be carried out if the ground is suspected of getting softer. Heavy rain and frozen ground thawing out can have adverse effects on MEWP stability.
MEWPs can be stabilised and perform safely and effectively on most surfaces and gradients provided a few basic things are taken into consideration. Get familiar with the machine’s warning devices and what it is capable of doing. Assess the ground conditions that you are working on to ensure you can use the machine to its optimum performance to help prevent avoidable stability accidents.