Tree work (arboriculture)

Cropped image of fallen tree

Every year people are seriously injured or killed while doing tree work. Most people injured have extensive experience in tree work.

Tree work includes all activities such as lopping, pruning, thinning, felling and removal of trees.

The causes of incidents vary significantly. Therefore, to reduce injuries, every hazard should be identified and their risks controlled by competent people.

Recent examples of workers being injured, or in one case dying from their injuries, include:

  • an experienced person was working unharnessed on a truck mounted elevating work platform (EWP) and fell to their death
  • a branch used to anchor the climbers rope (used to climb up and down the tree) failed
  • when a rope was pulled to break off the top part of the tree at the cut, the entire tree fell, as well as the climber.  The entire tree fell due to a rotten root plate, instead of breaking at the cut.
  • an anchor end of a climbing and descending rope was connected to the tree instead of the climber
  • a tree climber identified difficulties in executing an original safety method . The new method did not manage the risks of the lopped branches hitting persons, which caused a serious injury.

Hazards

Hazards could be known in advance or be unforeseen. Some possible hazards are:

  • condition and stability of the tree
  • falling or swinging objects including tree parts  that have been cut or have the potential to  break
  • onsite conditions that increase the risk of slips, trips and falls
  • manual tasks including pulling, pushing, lifting and plant vibration
  • electric shocks from energised power lines
  • working with plant including mobile plant
  • dehydration and fatigue
  • wind and rain
  • allergic reactions to trees and poisonous plants
  • biting or stinging eg by insects and snakes

Planning

  • only competent persons should undertake the assessment of trees and sites, planning and preparation of the work method
  • determine appropriate control measures in consultation with workers and document the safe work method to serve as evidence of managing risks
  • discuss the control measures at the tool box talk
  • consider conducting a site specific risk assessment
  • the risks that are common to many jobs may not be re-assessed but persons undertaking the work must be familiar with the current control measures in place
  • planning should consider whether the presence of plant such as an EWP will impede the cutting and lowering of tree sections
  • plan emergency rescue plans, including aerial rescue procedures with everyone involved
  • use of plant to access high sections can reduce fatigue and dehydration

Assessment of tree

Tree trunk was split up due to bark inclusions

Assess the condition and stability of the tree visually. This includes noting:

  • whether the tree is leaning heavily in one direction
  • if there is evidence of bark inclusion
  • if there are dead branches
  • any signs of decay in the tree structure
  • any signs of fungal fruiting bodies
  • any hollows
  • if there are branches intruding from nearby trees
  • the presence of any concealed nests or insect colonies
  • whether the tree type is susceptible to branch failure when under load
  • the stability of the tree root plate by pushing or pulling the tree and observing the ground movement

Presence of fungal fruiting bodies is an indication of decaying trees structure. Generally, the fungal part you can see is the fruit

Root plate failure

Accessing the tree

  • if a tree is not to be felled from the ground, conduct a site specific risk assessment to help you decide the safest way of accessing the tree which may include the use of an EWP, a crane or climbing
  • secure a suitable rope climbing system by using correct knots at a location on the tree which can withstand the forces of a fall
  • a risk assessment must be conducted if equipment which is not specifically designed to lift person is to be used to place a person on the tree eg a crane
  • climbing spikes can damage tree tissues which can result in infection and decay and can create future hazards

Competencies

  • make sure that only a competent and experienced person does the risk assessment, planning, and execution of work methods and is on site to identify hazards to, if necessary to, prepare an amended safe work method
  • make sure all workers performing jobs with common risks are familiar with current risk control measures in place
  • regularly remind workers of common controls and re-train workers as frequently as is necessary

Before tree work commences

  • communicate the work method to the workers
  • communicate the emergency rescue plans with everyone involved
  • provide clear access routes, enforce exclusion zones and implement the traffic management plan

Managing unforeseen risks

  • make sure that when any change or unforseen risk arises, eg change in wind speeds or changes to the ground condition after rain, new assessments, plans and on site management are undertaken
  • new or varied plans must be as thoroughly worked through as the initial work method

Power lines

De energise the nearby power lines. If this is not possible, maintain safe distances using tiger tails where necessary. Your safe work method needs to include information on how to avoid damaging power lines or any other assets in the vicinity. Electricity network operators also provide useful information.

A spotter should be available to alert the operator to hazards using a communications system understood by everyone involved.

Climbing

  • secure a suitable rope climbing system by using correct knots at a location on the tree which can withstand the forces of a fall
  • wear climbing spikes maintained as per manufacturer’s recommendations
  • climbing spikes can damage tree tissues which can result in infection and decay and can create future hazards
  • always maintain two points of attachments to the tree, particularly while cutting or moving on a dead tree eg use a flip line and a climbing rope

Plant and equipment

  • use plant only within its capabilities and in accordance with manufacturer’s recommendations
  • do not use mobile plant on soft ground, where underground assets are present, recently filled excavations, sloping or uneven surfaces, if not design for such purposes
  • ropes should not be attached to the plant
  • plant needs to be inspected and maintained as per the manufacturer’s recommendations
  • the top of the EWP basket should be located at the same level or above where the cut is made
  • workers in the EWP basket need to wear full body harness, to prevent being flicked out in the event the boom springs back, eg if the basket snags
  • do not carry fuel in the basket of the EWP

Chain saws

  • never drop start a chain saw when working on the ground
  • wear cut resistant leg protection, hearing and eye protection when using a chainsaw
  • start and warm up the chainsaw before climbing to prevent starting difficulty while the climber is on the tree