ISA Tree Risk Assessment 3

Question 1

In the ISA Tree Risk Assessment Qualification (TRAQ) methodology, what are the three components used to determine the overall risk rating?

Accepted Answer

Likelihood of failure, likelihood of impacting a target, and consequences of failure

Answer

The TRAQ risk assessment matrix evaluates three components: the likelihood that the tree or part will fail, the likelihood that the failure will impact a target (person or property), and the severity of consequences if impact occurs.

Question 2

What does 'target zone' mean in tree risk assessment?

Accepted Answer

The area within striking distance of the tree or its parts where people, property, or activities could be impacted by a failure

Answer

The target zone is the area that could be struck by the tree or its parts if failure occurs. Anything within this zone — people, structures, vehicles, utilities — is considered a potential target.

Question 3

Which of the following is considered a 'Level 2' assessment in the TRAQ system?

Accepted Answer

A basic assessment involving a detailed visual inspection of the tree from the ground, walking 360 degrees around it

Answer

A Level 2 (basic) assessment involves a thorough 360-degree ground-level visual inspection of the tree, examining roots, trunk, scaffold branches, and crown for structural defects, signs of decay, and other risk indicators.

Question 4

What structural defect is indicated when a tree develops a pronounced 'bulge' or swelling on one side of the trunk at the base?

Accepted Answer

A potential response growth indicating internal decay or structural stress on the opposite side of the bulge

Answer

Asymmetric bulging or swelling on the trunk often indicates reaction (response) wood formation in response to internal decay or structural weakness. The tree adds wood on the stressed side to compensate for lost strength.

Question 5

When assessing a tree with codominant stems, what visual feature indicates the highest probability of failure at the union?

Accepted Answer

A visible crack or seam at the union combined with included bark between the stems

Answer

A visible crack at a codominant union with included bark indicates the highest failure probability. The crack shows active separation, while included bark means the union lacks the interlocking wood grain that provides strong attachment.

(ISA) ISA Certified Arborist Practice Test

(ISA) ISA Certified Arborist Practice Test

ISA Tree Risk Assessment 3