The Quantified Tree Risk Assessment (QTRA) system applies established and accepted risk management principles to tree safety management.
QTRA moves the management of the risk from falling trees away from labelling trees as either ‘safe’ or ‘unsafe’ and thereby away from requiring definitive judgements of either tree surveyors or tree managers. Instead, QTRA quantifies the risk of significant harm from tree failure in a way that enables tree managers to balance safety with tree value.
Whether you own a single tree or manage a diverse population of thousands of trees, your approach to managing the risk from falling trees needs to be reasonable and proportionate.
If you have many unstable trees overhanging a busy highway, it is probably unreasonable to do nothing. On the other hand, allocating disproportionate resources to the reduction of risks that are already imperceptibly low will also be unreasonable because, amongst other reasons, those resources will have been diverted from the provision of other services.
By quantifying the risk of harm from tree failure, QTRA enables you to quickly map your trees in relation to land-use as a desktop exercise, which means that your resources can be directed first to the assessment of those trees or tree populations that present the highest risks.
In areas of low public access, the risk may be so low that an assessment of tree safety is unnecessary. Where the trees are assessed, the risks can often be quantified by taking a broad view of the tree population rather than making a detailed record of each and every tree.
QTRA provides a process by which the assessor can provide the odds of significant harm resulting from tree failure and the tree manager can make informed decisions rather than be coerced into carrying our costly risk averse management.