Tree risk: Safety in numbers and words
The world of tree risk assessment and management tends to fall into one of two camps. A ‘quantitative’ approach pioneered by Quantified Tree Risk Assessment (QTRA). Or the ‘qualitative’ route the International Society of Arboriculture has gone down with Tree Risk Assessment Qualification (TRAQ). This presentation will explore a best of both worlds, third way, that marries the benefits of both quantitative numbers and qualitative words.
Foundations will be laid down by exploring the key concepts of risk tolerance, how uncertainty in risk is best measured and expressed, and the principles that constitute good forecasting. With footings firmly fixed, the advantages and pitfalls from the clarity but implied exactness associated with numbers, and the simplicity but ambiguity attached to words, will be examined. A robust quantitative framework will then be constructed on which a qualitative superstructure is hung. The third way is an easy to understand and use, transparently proportionate, and cost-effective solution to the horns of the tree risk dilemma, that benefits both the tree risk assessor and tree risk manager.
David Evans is the Principal Consultant at The Arbor Centre. Having accidentally got into trees, whilst on a career path to becoming President of Chile, he has previously worked as a Climbing Arborist, Yellow Pages Binder, Arboricultural Lecturer, and Mud Volleyball Pitch Curator – though not necessarily in that order.
Apart from the consultancy work, for the last 10 years, David has been one of the principal QTRA and Probability of Failure trainers, delivering workshops internationally, and an invaluable contributor to the development of QTRA. He has presented at arboricultural events in the UK, USA, Canada, Netherlands, Australia, New Zealand, and Singapore.
David is currently dipping his toes back into the academic stream by undertaking a PhD into the VALID approach to estimating Likelihood of Failure in trees, and its role in tree risk assessment.