In June 2020, a man died after being struck by a tree he was cutting down with a chainsaw.
Initial findings indicate the tree may have not have fallen in the intended direction and caught the deceased by surprise.
Preventing a similar incident
Felling of 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 hastily retreats to a safe position once the tree begins to fall.
However, there are many factors to consider for a specific tree or site that increase the complexity of the process. Manual felling of trees should only be carried out by workers with appropriate training (e.g. arborist or industry-based qualifications), experience and competence for the particular tasks involved.
Common hazards and risks associated with felling trees using chainsaws can include, but are not limited to:
- hazardous trees, including damaged, hollow, non-symmetrical or leaning trees
- escape routes not clearly identified or prepared in advance
- being struck by the butt of the tree or the tree not falling in the intended direction
- unsuitable ground conditions and slope or environmental conditions (e.g. wind)
- falling objects e.g. limbs, dry stags, dead and brittle tops i.e. widow makers1
- kickback or recoil from the chainsaw
- unsuitable felling procedures or lack of appropriate planning and equipment
1 Widow maker: A limb or section of the tree that can fall at any time – source Safe Work Australia
The person conducting the business or undertaking (PCBU) must manage risks associated with felling trees. Risk management starts with a commitment to health and safety from those who manage the business. Managing work health and safety risks is an ongoing process and involves four steps, which are: identifying hazards, assessing risks, controlling risks and reviewing control measures to ensure they are effective.
Once the risks have been assessed the next step is to control risks. Control measures are ranked from the highest level of protection and reliability to the lowest and are known as the hierarchy of control. Duty holders must work through this hierarchy to choose the controls which most effectively eliminate or, where this is not reasonably practicable, minimise the risks.
Effective control measures are often made up of a combination of controls. Some common risk control measures may include, but are not limited to:
- Substitution – substitute the task of manual felling with mobile plant designed for mechanical felling. An example of this is to use a forestry harvester. However this may not be reasonably practicable in many circumstances. Alternative substitution controls may include:
- Where the tree cannot be clear felled. For example, 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. Note: An EWP may be assessed as a suitable alternative climbing 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). Other considerations when using mobile plant include 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, they may fail and recoil. Note: The use of mobile plant and cable type systems as alternatives where clear felling is not possible may also be considered engineering control measures.
- Isolation – establish 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 should 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’s felled.
- Engineering – in addition to mobile plant engineering controls, the following should also be considered:
- The chainsaw selected must be suitable for the task and the size of the tree – refer to the manufacturer’s recommendations and limitations on use. The chainsaw and its use should comply with the requirements of AS 2727:1997 Chainsaws – Guide to safe working practices. Chainsaws must be equipped with 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 be used to prevent the tree from leaning backwards or falling in the direction of the fellers escape route. However, using wedges may need to be avoided where there is a risk of dislodging limbs without a protective structure.
- All equipment used in the felling process, including mobile plant and tensioned ropes or cable systems, must be suitable for the task. For example, 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.
- Administrative controls – if risk remains, it must be further minimised by implementing administrative controls, for example:
- a safe system of work is in place that address site specific hazards for example; the establishment and adherence to exclusion zones
- workers are given relevant information and instructions and are trained and competent to perform the tasks
- the chainsaw and any ancillary equipment used should be selected and maintained in accordance with the manufacturer’s specifications or the advice of a competent person.
- Personal protective equipment (PPE) – depending on the task, any remaining risk must be minimised with suitable personal protective equipment. For example; hard hats; gloves; protective footwear; eye protection; hearing protection; high visibility clothing; cut resistant leg protection.
Adopting and implementing higher order controls before considering administrative or PPE controls will significantly reduce the likelihood of a similar incident occurring. The control measures you put in place should be reviewed regularly to make sure they work as planned.
eSAFE Incident Alert
July 22, 2020