AIE - Arb Tools - Arborcad software

aie_logo Tools & Equipment

QTRA - Quantified Tree Risk Assessment

The Quantified Tree Risk Assessment (QTRA) system is a tool to enable users to determine a level of risk produced by a tree to an adjacent target area. The system applies established and accepted risk management principles to tree safety management.

Firstly, the targets upon which trees could fail are assessed and quantified, thus enabling tree managers to determine whether or not and to what degree of rigour, a survey or inspection of the trees is required. Where necessary, the tree or branch is then considered in terms of both impact potential (size) and probability of failure. Values derived from the assessment of these three components are used to calculate the probability of significant harm occurring.

The system moves the management of tree safety 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 values and operate to a predetermined limit of reasonable or acceptable risk.

The process of the assessment can be carried out on paper or on a computer (PDA, laptop etc). Only licensed users (those which have completed a training course) are permitted to use the system. Full details are available on the QTRA website (see link below).

Link to the QTRA website
Link back to the Tools Index