Tree Risk Assessment
ArboricultureA systematic process of evaluating a tree's structural condition and site factors to determine the likelihood and consequences of failure.
Tree risk assessment is the formal process of identifying, analyzing, and evaluating tree-related hazards. Qualified assessors examine the tree's structure, health, and site conditions to determine the likelihood that part or all of the tree might fail, and what the consequences of that failure might be to people or property.
The assessment considers three components of risk: the probability of failure (how likely a branch or trunk is to break), the probability of impacting a target (whether people or property are in the fall zone), and the severity of consequences. Risk is rated from low to extreme, guiding management decisions from monitoring to removal.
ISA offers a specialized Tree Risk Assessment Qualification (TRAQ) that trains arborists in standardized assessment methods. A Level 1 assessment is a visual walk-by survey of many trees. Level 2 is a detailed visual inspection of a specific tree. Level 3 involves advanced techniques like resistograph drilling, sonic tomography, or aerial inspection for complex cases. Regular risk assessments are particularly important for trees near homes, roads, playgrounds, and other high-use areas.