Preventing death and serious injury when felling trees
In June 2020, a man died after being struck by a tree while he was cutting it down with a chainsaw. Initial findings suggested that the tree may not have fallen in the intended direction and caught the man by surprise. Felling trees with a chainsaw can be dangerous, particularly when the risks associated with it are not adequately controlled. When manually cutting trees, the feller normally stands at the base to operate the chainsaw and retreats to a safe position once the tree begins to falls.
However, there are many factors to consider for a specific tree or site that increase the complexity of the process. The manual felling of trees should only be performed by workers with appropriate training (such as arborists or those with industry-based qualifications), experience and competence.
Common hazards and risks associated with felling trees using chainsaws can include hazardous trees (including damaged, hollow, non-symmetrical or leaning trees), escape routes not clearly identified or prepared in advance, or the tree not falling in the intended direction. Unsuitable ground conditions and slopes, environmental conditions (such as wind) and falling objects (such as dry stags and dead and brittle tops) also pose risks. Kickback or recoil from chainsaws and inadequate felling procedures or lack of appropriate planning are also hazardous when felling trees.
The person conducting the business or undertaking (PCBU) must manage risks associated with felling trees. Managing work health and safety risks is an ongoing process and involves four steps: identifying hazards, assessing risks, controlling risks and reviewing control measures to ensure their efficacy. Once the risks have been assessed, PCBUs must control the risks. Control measures are ranked from the highest level of protection and reliability to the lowest, and are known as the hierarchy of control. PCBUs must work through this hierarchy to choose the controls which most effectively eliminate or minimise the risks. Effective control measures can often be comprised of a combination of controls.
PCBUs can substitute the task of manual felling with mobile plant designed for mechanical felling, such as by using a forestry harvester. However, this may not be appropriate in some circumstances. Where the tree cannot be clearly felled, an elevating work platform (EWP) may be required to remove the crown of the tree before it can be safely felled in the required direction (an EWP could also serve as a suitable alternative to climbing up the tree to remove the crown).
Other mobile plant or ropes and cable type tensioning systems may be used to help ensure the tree will fall in the desired direction; for example, bulldozers or excavators fitted with Level 2 Falling Objects Protective Structure (FOPS). When using mobile plant, PCBUs should also consider ground slope (where there is a risk of the plant overturning) and if components of rope or cable type systems do not have adequate strength to perform the required function or are incorrectly rigged.
PCBUs should also consider establishing a safe area or exclusion zone to ensure people and machines not involved in felling do not come within two tree lengths of the operation. Observers must be used to monitor the exclusion zone. If working on sloping ground, the exclusion zone may need to be extended, where there is a risk of the tree sliding further down the slope once it is felled.
The chainsaw selected must be suitable for the task and the size of the tree (as per the manufacturer’s recommendations and limitations on use). The chainsaw and its use should also comply with the requirements of AS 2727:1997 Chainsaws – Guide to safe working practices. Chainsaws must also have a reliable off switch, chain catcher, rear hand guard, anti-vibration handle mountings, throttle lockout, efficient muffler, chain brake and front hand guard.
Holding wedges can also be used to prevent the tree from leaning backwards or impeding the feller’s escape route. However, holding wedges should not be used when there is a risk of dislodging limbs without a protective structure. All equipment used in the felling process, such as cables connected between the tree and plant, must have adequate strength and be long enough to allow the plant to be at a distance of twice the tree height.
If the risk remains, then PCBUs should implement administrative controls, by ensuring that a safe system of work is in place that addresses site specific hazards, such as exclusion zones. PCBUs must also ensure that workers receive relevant information and instructions, and are trained and competent to perform the tasks. The chainsaw and any ancillary equipment used should also be selected and maintained in accordance with the manufacturer’s specifications.
Any remaining risk should be minimised with suitable personal protective equipment (PPE), such as hard hats, gloves, protective footwear, eye protection, hearing protection, high-visibility clothing and cut-resistant leg protection. Implementing higher order controls before using administrative or PPE controls will reduce the likelihood of a similar incident occurring. Control measures should also be reviewed regularly, to ensure they work as planned.
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