01803 813717 info@darttree.co.uk

Tree Safety

Tree safety and risk assessment using

Quantified Tree Risk Assessment (QTRA)

We use the Quantified Tree Risk Assessment (QTRA) methodology when assessing trees for risk. This system allows us to make best use of our time whilst on site, meaning we spend more time looking at your trees and less time recording superfluous data. This allows for cost effective tree risk assessment. The results of which can be used and compared with other risks on your property and priorities for safety work are easily found.

A non-technical description of the QTRA methodology

Tree safety management is a matter of limiting the risk of harm from tree failure while maintaining the benefits conferred by trees. Although it may seem counter intuitive, the condition of trees should not be the first consideration. Instead, tree managers should first take account of the usage of the land on which the trees stand, which in turn will inform the process of assessing the trees.

Tree with Ivy, tree Safety, Dart Tree Consultancy

Tree Safety Management

Quantified Tree Risk Assessment (QTRA) applies established and accepted risk management principles to tree safety management in accordance with ISO 31000:2009,

Risk management – Principles and guidelines, which is published by national standards agencies.

By quantifying the Risk of Harm as a probability, QTRA enables the tree manager to manage the risk from tree failure to widely accepted risk thresholds. Firstly, the targets (people and property) upon which trees could fail are assessed and quantified, thus enabling tree managers to determine whether to assess trees and to what degree of rigour a survey or inspection of the trees is required. Where necessary, the tree is then considered in terms of both size (potential impact) and probability of tree or branch failure. Values derived from the assessment of these three components (target, size and probability of failure) are combined 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 requiring definitive statements of tree safety from either tree surveyors or tree managers. Instead, QTRA quantifies the risk of harm from tree failure in a way that enables tree managers to balance safety with tree value and operate to predetermined risk thresholds.

Property owners and managers have a duty under English law to ensure, insofar as ‘reasonably practicable’, that people and property are not exposed to unreasonable levels of risk from the failure of trees in their control.

Our risk assessments provide a risk category and where necessary, specify remedial works to reduce that risk to an appropriate and agreed level.

If you are at all concerned about your trees call us to talk through your options and get some advice on how best to proceed.

You can find out more about our clients here.

Get In Touch

01803 813717


Wrigwell Estate, Ipplepen, Newton Abbot, TQ12 5UA

River View Place, Kingsbridge, TQ7 1BN

Contact Us

Contact us now to speak to one of our consultants for free advice on how to proceed.

Keith McBride

07852 318606

Stewart Killick

07967 730771