TRAQ
Tree Risk Assessment Qualification

A TRAQ-style assessment rates two things independently, then combines them. Failure likelihood is scored improbable, possible, probable, or imminent — how likely is this specific defect to actually cause part or all of the tree to fail in the assessment window. Consequence is scored negligible, minor, significant, or severe — what happens if it does fail, based on what's underneath (a shed, a footpath, a parking lot, a bus shelter).

Those two scores combine into a single risk rating: low, moderate, high, or extreme. A tree with a probable failure likelihood over an empty field rates lower than the same defect over a school playground — the tree isn't more or less dangerous in isolation, the target changes the number.

ISA's Best Management Practices define three levels, and most consulting work happens at Level 2. Level 1 is a limited visual assessment — a quick walk-by screening, often used to triage a large population of trees. Level 2 is a basic assessment: a full walk-around inspection from the ground, checking all sides of the tree, the root collar, and the site conditions around it. Level 3 is an advanced assessment — used when Level 2 turns up something ambiguous, and may bring in resistance drilling, sonic tomography, or an aerial inspection to look inside the stem or root system.

A defensible risk assessment isn't a gut call — it's built on the same field observations as a normal inventory (species, DBH, condition) plus a specific risk layer: failure likelihood, consequence, the resulting rating, what the "target" is (the thing that would be hit), any mitigation recommended, and a reinspection date. That reinspection date matters more than it sounds like it should — a risk rating is a snapshot, not a permanent verdict, and a documented reinspection interval is part of showing the assessment was taken seriously.

Read more on running a full assessment in the tree risk assessment guide, or see how LogLog records risk fields — failure likelihood, consequence, rating, target, mitigation, and reinspect date, tied to the tree pin on your site plan.