ISA TRAQ common mistakes
ISA TRAQ · Understand the traps and how to avoid them.
Assigning a risk rating (e.g., 'low' or 'high') from the target and defect alone, without first completing the likelihood-of-failure and likelihood-of-impact steps and combining them in the TRAQ matrix.
Candidates carry over informal arborist intuition ('that limb looks sketchy') and skip the two-axis structure the method requires, so the final rating reflects gut feel rather than the matrix cell.
What to do instead
Before writing any rating, explicitly record likelihood of failure (improbable/possible/likely) and likelihood of impact (very low/low/medium/high) as separate entries, then read the rating from the matrix intersection. Practice by writing both axes in the field notes for every tree, even obvious ones.
Treating likelihood of impact as equivalent to occupancy rate or conflating it with likelihood of failure when the target is only occasionally present (e.g., a picnic table used seasonally).
The two likelihoods use different vocabularies and time frames, and candidates memorize the matrix layout without internalizing that impact depends on target presence and exposure, not on tree condition.
What to do instead
State the target, its occupancy pattern, and the exposure window in writing before selecting likelihood of impact. Use worked scenarios with intermittent targets to drill the distinction until the two axes are never merged in notes.
Recording a risk rating without specifying the time frame or qualifying it as 'risk now' versus 'risk over time,' then failing to note how the rating changes if the target or tree condition changes.
TRAQ ratings are conditional and time-bound; candidates who omit the qualifier produce answers that cannot be defended when the scenario introduces a change such as new construction or a target removed.
What to do instead
Write the rating as a complete statement: matrix cell, time frame, and the assumption about target and condition. On practice items, add a one-line 'what would change this rating' note to force awareness of the conditional nature.
Confusing tree risk assessment with tree health or hazard diagnosis, spending the answer on decay fungi identification or pruning prescriptions instead of the risk conclusion and mitigation options.
Candidates with strong arboriculture backgrounds default to diagnostic detail, and the exam's risk-management framing is easy to under-weight under time pressure.
What to do instead
Structure every response as: assessment scope, findings relevant to failure likelihood, target and impact, rating, and mitigation options with residual risk. Keep diagnostics only as far as they change likelihood of failure.
Skipping the site and target inventory, then rating impact from an assumed occupancy rather than an observed one.
Field habits often start at the trunk; the target is treated as obvious and never documented, so impact ratings default to a guess.
What to do instead
Adopt a fixed walk-around sequence: define the assessment area, inventory targets and occupancy first, then inspect the tree. On practice items, list targets before listing defects.
Misjudging likelihood of failure by ignoring the difference between a defect's presence and its severity, e.g., rating any cavity or included bark as 'likely' failure.
Candidates memorize defect names without the size, position, and load relationships that drive failure likelihood, so every defect gets the same weight.
What to do instead
For each defect, record location, extent relative to the supporting stem or root, and the load it must carry, then justify the likelihood of failure against those specifics. Use comparative practice sets where similar defects differ in severity.
Failing to distinguish the assessment level (limited visual, basic, advanced) and answering an advanced-level scenario with limited-visual reasoning or vice versa.
The levels differ in tools, time, and what can be concluded; candidates blend them and give conclusions the stated level cannot support.
What to do instead
Identify the level from the scenario's stated scope, tools, and time, and match conclusions to that level. State explicitly when a finding requires escalation to a higher level rather than asserting it directly.
Recommending mitigation without addressing residual risk, or recommending removal as the only option when pruning, support, or target relocation would reduce risk proportionally.
Candidates treat mitigation as a single correct action and forget that the rating must be reassessed after treatment; over-recommending removal also signals a misunderstanding of risk tolerance.
What to do instead
For each scenario, list at least two mitigation options with the resulting likelihood of failure and residual rating, and tie the recommendation to the client's risk tolerance and objectives.
Using undefined or non-standard terms for likelihood, impact, and rating (e.g., 'moderate-high,' 'dangerous,' 'safe') instead of the specified categories.
Everyday language feels natural and candidates do not rehearse the exact category vocabulary, so answers cannot be mapped to the matrix.
What to do instead
Memorize the exact category labels for both axes and the rating set, and use only those words in written answers. Do timed drills writing full risk statements using only approved vocabulary.
Omitting the basis and limitations of the assessment (scope, date, tools used, what was not inspected, e.g., roots or upper canopy) from the written conclusion.
Candidates focus on the rating and treat documentation as boilerplate, but an unsupported rating is indefensible and the exam tests whether the conclusion is traceable to evidence.
What to do instead
End every practice answer with a short basis-and-limitations statement: scope, methods, inaccessible areas, and assumptions. Treat it as a required section, not an optional add-on.