Arbor Australis Consulting

AQF 5 Arborist Brisbane

Brisbane | 07 3379 7793

Sunshine Coast | 0438 007 761

Arboricultural Risk Assessments

Tree Risk Assessment

To meet the needs of our clients, our AQF Level 5 Consulting Arborists are licensed and trained users of the Quantified Tree Risk Assessment (QTRA), the Tree Risk Assessment Qualification (TRAQ) and VALID tree risk assessment methodologies.  VALID is the default system used by Arbor Australis Consulting and is integrated into our school and golf course management plans. Tree risk assessments form an integral part of our everyday operations, assisting in the identification, assessment and quantification of risks in trees.


We will listen to clients’ concerns about tree risk and, through tested methodologies, apply a robust risk assessment to clarify actual risk rather than perceived risk. From these assessments, recommendations are made to manage risk, and a written report is provided to support all findings.

VALID Tree Risk

System Summary:

The Valid Tree Risk Assessment system has been developed to apply ISO 31000 and the Tolerability of Risk Framework (ToR). The system, like many tree risk assessment systems, is based on the following factors:

  • Occupancy Range i.e., the frequency of people or property within the fall zone of a failure
  • Consequence i.e., size and extent of a possible failure that may hit the occupied area.
  • The likelihood of the failure occurring based on VALID inputs

The system calculates the risk of harm based on the likelihood of tree failure based on the tree condition assessment inputs, the occupancy of the area, and the consequence based on the size input, should a failure occur. The ToR framework provided the categorisation of outputs. VALID provides a framework of action required to address the determined risk. 

Risk Output Summary:

Red: Not Acceptable – risks will be reduced to an acceptable level

Amber: Not Tolerable – risks will be reduced to an acceptable level, but with a lower priority than Not Acceptable risks

Amber: Tolerable – risks will not be reduced but may require an increased frequency of assessment than the Green Acceptable risks

Green: Acceptable – risks will not be reduced

Tree Risk Assessment Deliverables

  • Basic Risk Assessment – visual assessment from the ground. this level is used to identify the trees that require a detailed assessment
  • Detailed Risk Assessment – the VALID App is used to produce a risk assessment based on visual assessment inputs.
  • Advanced Assessment – the use of diagnostic tools and/or aerial assessment to further inform the assessment inputs
Tree Fialure
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