Hopefully there is nobody thinking about balancing along the ridge of a greenhouse, leaning off a ladder to cut a tall hedge or shinning up a tree without a care in the world. If you are, stop right now.
The introduction of the Work at Height Regulations 2005 (WAHR) brought about a radical rethink of how tasks such as repairing glasshouses, hedge maintenance and aerial tree-work should be undertaken. The Health & Safety Executive want to see that everything reasonably practical is done to prevent anyone falling.
The first approach is avoidance - don't go up there unless you have to. And where working at height cannot be avoided, the work must be properly planned, supervised and carried out safely. This means that anyone involved with planning, supervising and/or undertaking the work must be trained and competent. It also means a rescue plan should be prepared and equipment provided on site to deal with emergencies.
And it means considering the use of mobile elevating work platforms (or MEWPs) ahead of rope access equipment, balancing on ladders or using crawler boards.
Widely seen used in the construction and building-maintenance industries, the use of MEWPs has really taken off in horticulture and arboriculture over the past decade. Now there is a wide choice of manufacturers and, more importantly, of type of MEWP suited to the sector.
The type must be chosen to reflect the tasks to be performed, access to the area and the ground conditions at the time, as well as having the required height, outreach and load. Clearly, the height and width of entrances, the space available for on-site travel and for set-up, along with the height of the object being maintained, will all affect the size of MEWP selected.
MEWPs can be rated for flator rough-terrain use. They can be classed as suitable for use on level, firm surfaces such as concrete, rough terrain or roads. Gradients and surface traction should also be considered - fourwheel-drive and tracked models are able to cope where some others will not.
Tracked units, although slower, exert lower ground pressure than wheeled ones and so have the advantage where the ground is soft or liable to damage, but it is important to remember that these are heavyweights. Narrow machines can overturn or control can be lost when travelling alongside trenches or where the ground conditions suddenly change. Vehicle-mounted MEWPs can be driven on roads and play an important role in the maintenance of closely-sited street trees.
Different types also have different characteristics, making them suitable for specific applications. Of the vertical-lift MEWPs, scissor lifts are suited to hedgecutting and other tasks where no outreach is required. Boom-type MEWPs may have telescopic or articulating booms, allowing outreach at a distance from the standing position.
The telescopic type, however, is limited to work in line from the standing position. To reach up and over objects, the articulating-boom MEWP comes into its own. For work within a tree, booms with an articulating fly jib and/or rotating platform should prove versatile.
Basket capacity should be selected in terms of the number of people it needs to carry, the suitability of anchor points, facilities for running powered equipment and the size for work positioning.
One of the latest units available is the new Leo 13GT from German manufacturer Teupen and distributed by Ranger Equipment of Chesterfield. An entry-level MEWP, the Leo 13GT is a tracked spiderlift with 12.8m working height. It joins a 10-model range crowned by the world's largest "production line" tracked spiderlift, the Leo 50.
Ranger Equipment managing director Steve Hadfield says: "The Leo 13GT is priced to take on competing 13m spiderlifts and higher-specification trailer lifts in an important sector of the aerial work platform market where there is demand for more sophistication."
The Leo 13GT has a maximum outreach of 6.1m at its maximum capacity of 200kg even at full working height. Automatic outrigger levelling is standard.
Launched this year, and representing the world's first hybrid MEWPs, Niftylift's HR21 Hybrid AWD and the HR17 Hybrid AWD feature a power pack that allows the selection of "electric only" or "hybrid power" during operation.
On "electric only" the unit becomes a zero-emission machine for clean, quiet work indoors or out. On "hybrid power" the HR21 and HR17 allow the electric motor to automatically assist the diesel engine when required - perhaps when climbing a steep slope.
At all other times, the electric motor channels the excess power from the diesel engine back to the batteries. The hybrid technology also means that the machine can use a smaller diesel engine than would otherwise be required.
New from CTE UK is the Traccess 230. It is a 23m tracked-access platform designed for climbing slopes, the 230 is only 80cm wide yet its 200kg basket-capacity is unrestricted up to 12m. Sigma boom configuration on this machine enables vertical plane work with just one control.
The Arboricultural Association has published A Guide to the use of MEWPs in Arboriculture. The 76-page booklet looks at the safe use of mobile elevating platforms, including set up, use for tree work, use on highways, rescue and all the legal considerations.
CASE STUDY: Leo works close to the river
Aerial tree-work can be even more difficult when the tree is located in an awkward setting. Such a case arose when Shrewsbury & Atcham Borough Council, now Shropshire Council, was alerted to signs of decay in a 100-year-old tree growing on the banks of the River Severn in Shrewsbury.
The unusual hybrid poplar dominates a cluster of trees in public gardens adjacent to Shrewsbury's historical English bridge and fronting the Wakeman High School. The challenge was taken up by Shropshire tree surgeons Benbow Brothers.
To ensure that the tree posed no safety risks to the public passing below, Benbow Bros was advised by the council's tree officer to make a 30 per cent reduction to the canopy and return it to a sound and healthy condition to assure the conservation of what is deemed a strategic and cherished natural landmark.
The possible presence of weakened branches and the proximity to the river ruled out climbing. Narrow access to the site, uneven terrain and the sheer height and outreach required to tackle the task also set tough performance criteria.
The solution was to use the world's largest tracked-chassis "spiderlift" - the Teupen Leo 50 - from UK and Ireland distributor Ranger Equipment. With almost 50m working height, the rough terrain model (Leo 50GTX) has 17m working outreach at 200kg basket-capacity and a possible 20m at 80kg basket-capacity.
Benbow Bros Tree Care division director Ken Benbow says: "After carrying out a risk assessment, it was clear we would not be able to climb the tree to do the task and it was also obvious a normal MEWP would not give the outreach we needed at the height required. With the safety, conservation and site constraint issues involved, the Leo 50 was the best solution and reduced the safety hazards involved in maintaining what is an important and strategic tree."
To complete the reduction, two tree surgeons with a chainsaw used every bit of the 17.4m outreach offered by the telescopic upper boom. Benbow Bros' senior tree surgeon Chris Hearne explains: "The long outreach meant we could get out to the ends of the branches and work inwards. This allowed us to remove branches in smaller, more manageable sizes that we could comfortably handle and dispose of safely."
The two-man team in the basket had to cyclically retract outreach while working on the outermost branches that overhung the river. In this way they ensured that no debris fell into the water. Work rate while doing this was buoyed by the Leo's responsive manoeuvring capabilities - including a fly jib and patented 180 degs basket rotation with corner pivot design that allowed the basket to be angled to lead its narrowest edge into foliage.
"With tree reduction, there is a great deal of manoeuvring required around limbs because you don't want to damage healthy parts and areas that you have dealt with. We found that, for its size, the platform was very manoeuvrable. The fly jib and swivel cage in particular meant we could get ourselves to just the right place each time."
The Leo 50 is a big machine. It weighs 13,500kg. Yet it exerts relatively low ground-bearing pressure and low surface-load pressure - less than 2.9kN/m2 - so protecting grass and gravel. Additionally, the tracked chassis spreads loads across a large contact area, so avoiding the compaction of fibrous root systems.
The tracking has good grip for traversing sand, gravel, slopes and uneven ground, while generous-sized pads on the feet of the stabiliser legs also create a cushion against the ground when in the working position.
With the legs deployed, the chassis stakes out a significant area of ground to provide the required stability for the platform at full height and outreach. With the stabilisers stowed, however, the Leo 50 has a compact transport width of just 1.58m.
Access Platforms: 01480 891251
CTE UK: 0116 286 6743
NiftyLift: 01908 857853
Oil & Steel: 01604 750092
Overland Environmental Services (Arbtruck): 0118 981 4297
Ranger Equipment: 01246 477729