You may have noticed that there are two commonly used types of risk assessment fo
r trees; “Quantified Tree Risk Assessment” (QTRA) which has been developed by Mike Ellison of “Chesire Woodland” in the United Kingdom and the “Tree Risk Assessment Qualification” (TRAQ) which has been developed by the International Society of Arboriculture.
The aim of both systems is to assist Arborists to gauge the level of risk a tree may pose to people or property from either parts that may fall, or the whole tree falling.
Both systems have been developed by industry experts and have a high level of rigor, they are based upon levels of probability of a chain of events taking place, the presence of people based upon the area, weather, and type of activity. The most obvious difference is how they express the outcome, or what we call “Risk of Harm”
QTRA is solely based upon a range of mathematical probabilities and expresses its ROH as a number, the TRAQ system uses words to basically express the same thing.
Both systems have their place and we are happy to discuss which system is best used in your scenarios.
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