Review of QTRA and Risk-based Cost-benefit Assessment of
Mark G. Stewart, Dealga O’Callaghan, and Mark Hartley
Abstract: Quantified Risk Assessment (QRA) has been in wide use in risk management since the 1960s for systems ranging from aviation, nuclear power, and offshore platforms to medical treatment and pharmaceuticals. The Quantified Tree Risk Assessment (QTRA) system is examined considering the principles of QRA. A case study of 14 fig trees in Newcastle, Australia, illustrates some limitations of the QTRA process, and extrapolating risks for a single tree to a group of trees. There is a need for any risk management process involving trees, not only to assess the risk, but to weigh the benefits provided by trees by a risk-based cost-benefit analysis. Tree risk assessors should rely on benchmarks to ensure that their assessment is not outside of the realms of reality or scientific rigor.
Keywords: Australia; Cost-benefit Analysis; Quantified Tree Risk Assessment; Risk; Risk Management; Trees.