Accessing a tree presents with common hazards and risks which have to be properly evaluated before getting started on a jobsite.
Methods For Accessing Trees
Trees can be accessed by using EWPs or climbing.
PPE should be used for all access tasks. This can include eye, hearing, hand and leg protection as well as protective boots and helmet.
Clothing should generally be close fitting and of high-visibility. If using a chainsaw in a tree pants should be cut-resistant – see AS/NZS 4453.3:1997 Protective clothing for users of hand-held chainsaws – protective legwear.
Workers carrying out above ground work should be qualified for the type of work being done.
Before accessing a tree by any method a visual tree assessment should be carried out by a competent person. The assessment should include the tree’s overall condition and structural integrity with consideration given to structural faults like bark inclusions, decay, hollows, growth habit, species of tree and root plate failure. The assessment should also consider wind loading and the tree’s location. This information should inform whether the tree is safe to access, the method to access and attach to the tree, emergency rescue measures along with rigging and removal techniques.
Common Hazards And Risks Of Accessing Trees
- Slipping out of harness not positioned correctly
- Slipping or falling from branches due to failure of anchor points
- Dehydration and fatigue
- Musculoskeletal disorders from awkward positions
- Falling from height due to incorrect use of ropes, knots and devices like descenders
- Being struck by falling objects or a throw bag
- Wildlife related injuries e.g. from wasps, bees, birds, possums
- Falling from an EWP
- Contact with overhead electric lines.
Examples Of Control Measures For Accessing Trees
- Checking the location of overhead electric lines before starting work
- Conducting a site specific hazard and risk assessment
- Using an EWP
- Using a rope access system
- Establishing and maintaining an exclusion zone
- Having a spotter to maintain the exclusion zone while work is being done in the tree
- Ensuring the harness and climbing spikes fit correctly and are comfortable
- Being attached at all times e.g. to an EWP
- Planning a clear access route
- Checking the tree for bees, wasps or other animals before accessing
- Checking anchor points thoroughly before leaving the ground
- Weighting your climbing system before disconnecting your second point of attachment
- Having an emergency plan including an aerial rescue procedure
- Ensuring traffic control measures are in place within the established exclusion zone when working on or above roads.
Climbing A Tree
Other methods of accessing trees, for example using EWPs should be considered before attempting to climb a tree. Tree climbing is a dangerous and complex activity. It should only be done by workers assessed as competent against the relevant national UoC. Tree climbing should only be done by people who are physically fit and not affected by alcohol or drugs including prescribed medication which may affect or impair their ability to work at heights. Before climbing a tree a risk assessment should be conducted by a competent person to consider any special techniques required and weather conditions.
Tools carried and used by the climber should be safely secured when not in use. If the climber is using a chainsaw the climber should be secured to the tree using steel-core rope flip-lines that provide two points of attachment at all times. Some species of tree or damaged trees may require two points of attachment when moving location.
The chainsaw should be secured to the climber in a way that allows the chainsaw to hang in a position that will not hinder the climber’s free movement or create a hazard for the climber or other workers. When climbing large trees in hot or humid climates the climber can suffer dehydration and fatigue from humidity and heat. Therefore, frequent drinks and work breaks may be required.
Overhead electric lines running through trees may also expose a climber to the risk of electric shock resulting in electrocution.
The climbing crew should consist of at least two workers with one worker to stay on the ground as a safety observer or spotter. The nominated ground worker should also be trained in aerial rescue techniques.
The tree climber and ground worker should ensure regular visual or verbal communication is maintained. An exclusion zone must be established before work starts to ensure pedestrians and others are not entering the danger zone.
Tree Climbing Equipment
Tree climbing equipment must be suitable for its intended use, be used and maintained in accordance with the manufacturer’s instructions and be stored and protected from damage including during transit. Equipment used to climb a tree can include:
- Karabiners and snap hooks
- Ascenders, descenders and rope grabs
- Climbing irons (spikes)
- Lanyards, and Pulleys
Tree climbing equipment should be inspected and assessed by the climber before and after each use. A competent person who is not the regular user of the equipment should also check the equipment regularly, for example every three months. Cleaning and maintenance of tree climbing equipment should be carried out on a regular basis according to manufacturer’s instructions.
Further guidance is in relevant Australian Standards including AS/NZS 1891.4:2009 Industrial fall-arrest systems and devices – Selection, use and maintenance.
Single rope access systems Single rope access systems can be used to access some trees, usually by vertically suspended ropes. This should only be carried out by workers who have been trained and are competent in this method of accessing trees.
When the integrity of the tree may make it unsafe for a worker to work in the tree or where there are doubts the tree can hold the load, other methods for access should be used, for example EWPs. The potential for contact with overhead electric lines should also be considered when using this method.
Crane Access Method
Another access method for carrying out tree trimming and removal work is by lifting or suspending a person in a harness with a crane – Regulation 221 of the model WHS Regulations. Queensland, the Northern Territory and New South Wales allow this method to be used to access a tree. You should contact your local regulator for further information.
There are significant risks accessing trees using ladders. Tree trimming or removal work should not be done from ladders.
Further information can be found on the Australian Government’s training website – https://training.gov.au/