Hazard and Risk Assessment Flashcards

When assessing a tree near a target, which factor MOST directly determines risk magnitude?

Answer: Likelihood of failure multiplied by consequences

Risk magnitude is determined by multiplying the likelihood of failure by the consequences if failure occurs.

A tree arborist notices a co-dominant stem with included bark. Which term best describes this structural defect?

Answer: Weak attachment

Included bark between co-dominant stems creates a weak attachment point that significantly increases failure potential.

Which inspection method is most appropriate for detecting internal decay that is not visible externally?

Answer: Resistograph or sonic tomography

Instruments like the Resistograph and sonic tomography can detect internal decay columns not apparent during visual inspection.

A large dead branch over a playground is identified. According to ANSI A300 Part 9, what is the appropriate risk category when likelihood of failure is high and consequences are severe?

Answer: Extreme risk

High likelihood of failure combined with severe consequences (occupied target) places a hazard in the Extreme risk category.

Which of the following site conditions increases the likelihood of tree failure during a wind event?

Answer: Saturated soil with shallow root plate

Saturated soil weakens root anchorage, making trees far more susceptible to windthrow during storms.

What does the term 'target' refer to in a tree risk assessment?

Answer: People, property, or activities that could be injured or damaged

A target is any person, vehicle, structure, or activity that would be harmed if a tree or tree part failed and struck it.

An arborist observes carpenter ant activity at the base of an otherwise healthy-looking tree. What should be the next assessment step?

Answer: Probe and sound the base for internal decay

Carpenter ants nest in decayed wood, so their presence signals potential internal decay requiring further probing and sounding.