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Thought this might be of interest to some of you. It’s an updated and improved version of a Tree Risk Assessment review article that’s going out in this week’s NZ Arb’s Tree Matters, and was in Australia’s Arbor Age last month. I’ve made some alterations to the text and images to what’s going to be published so it's a better reference document. Mainly so the images are arranged closer to the point in the text where they’re discussed. I’ve also updated the App screen grabs to make them current. They include the people icon at the bottom right which lets you work out whether the combination of traffic and people means the occupancy should be one category higher. In this case, if you include people is the likelihood of occupation 1 Very High instead of 2 High? Tree Risk Assessment - Review.pdf

Hi In February of this year, 8 year old Bridget Wright tragically died when she was hit by a branch that failed from a tree at her school in Pitt Town, north-west of Sydney, Australia. On the back of that incident the Department of Education in New South Wales produced a directive to inspect trees in all state public schools for safety. In order to meet the criteria of the directive arborists had to be qualified to Level 5, and be a QTRA Registered User or have completed the ISA’s Tree Risk Assessment Qualification (TRAQ); TRAQ is founded on the ISA’s Best Management Practices - Tree Risk Assessment (‘Risk BMP’). I was in Sydney, and other cities in Australia, in March delivering QTRA & VTA workshops, and was asked by a number of TRAQ arborists whether there was scope for QTRA and the Risk BMP to work in tandem. This point has also been raised by some QTRA Registered Users, who are ISA members, and were looking to become ISA TRAQ accredited. During the Australian trip, and by email and phone after it, I’ve been discussing the Risk BMP with arborists who have attended both courses, and going through the Risk BMP publication along with the manual that accompanies the TRAQ training. What I’ve been looking to try and do is see where the common ground is, and what the Risk BMP risk rankings of ‘Extreme, High, Moderate, and Low’ mean in terms of actual risk. By way of background. QTRA quantifies tree risk using Monte Carlo simulations and a manual or software calculator to produce a Risk of Harm as a probability, which is the ‘risk assessment’. The level of risk can then be compared to levels of tolerable and acceptable risk in the Tolerability of Risk (ToR) Framework by the risk owner (client/manager) who makes the ‘risk management’ decision. The QTRA approach to tree risk assessment, including an advisory on risk management, is outlined in the QTRA Practice Note; Quantified Tree Risk Assessment The Risk BMP uses two matrices. A Likelihood of Failure & Likelihood of Impacting the Target Matrix, which produces a ‘Likelihood’ ranking. Then the Likelihood ranking is fed into a Risk Matrix, where ‘Consequences’ are also ranked, to produce a qualitative risk ranking of ‘Extreme, High, Moderate, or Low’, which is the ‘risk assessment’. The client then manages their level of tree risk at Extreme, High, Moderate, or Low depending on their ‘risk tolerance’, and this constitutes the ‘risk management’ decision. Those of you who are unfamiliar with the Risk BMP can read about it in Arborist News here; Risk BMP I’ve reproduced the two Risk BMP matrices below, which I've abbreviated to the 'Likelihood Matrix' and 'Risk Matrix', and coloured the cells to make it easier to identify the cell categories in each matrix. What I would like to do, with the help of TRAQ arborists and anyone else who would like to chip in who is familiar with the Risk BMP, is to go through the process of working out where the risks of ‘Extreme, High, Moderate, and Low’ sit in ToR. I’m going to break this up into easy to digest bite-sized pieces and will start the next post by looking at ‘Likelihood of Impacting the Target’ in the first matrix. Cheers Acer ventura Update - There is now a formatted and referenceable summary of this thread available as a pdf document, which can be downloaded at the first post of the new thread here: http://arbtalk.co.uk/forum/general-chat/88697-tree-risk-assessment-traq-qtra-compatibility-common-ground.html .