Waller Tree Consultancy

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Tree risk assessments using the Quantified Tree Risk Assessment (QTRA) methodology provide a structured and evidence-based approach to evaluating the level of risk posed by trees. QTRA is a recognised system used within the arboricultural industry to assess the likelihood of tree failure, the potential impact on people or property, and the overall level of tolerable risk. This approach allows tree owners and managers to make informed, proportionate, and defensible management decisions.

Assessments consider a range of factors including tree condition, structural defects, site usage, occupancy levels, and the likelihood of harm occurring. By quantifying risk rather than relying solely on subjective judgement, QTRA helps prioritise management works where they are genuinely required, avoiding unnecessary interventions while maintaining appropriate safety standards.

This approach closely aligns with the guidance produced by the National Tree Safety Group (NTSG), which promotes a balanced and common-sense approach to tree risk management. NTSG guidance recognises that trees provide significant environmental, social, and economic benefits, and that risk should be managed in a proportionate and practical manner rather than through unnecessary removal or excessive intervention. The guidance clearly explains the duties and responsibilities of tree owners and managers and is widely regarded within the industry as essential reading for anyone responsible for trees.

Importantly, both the QTRA methodology and NTSG guidance help protect against unnecessary tree removal by placing risk into a measurable and realistic context. Trees are often removed due to perceived rather than actual risk, particularly where defects or visible decay are present. QTRA supports balanced decision-making by assessing the true level of risk in relation to site use and target occupancy, helping retain valuable trees where risks remain low or manageable through appropriate maintenance.

As a QTRA trained and registered user, assessments are carried out in accordance with recognised industry methodology and current arboricultural best practice, providing clients with professional, transparent, and defensible risk evaluations supported by proportionate risk management principles.

QTRA Assessments are suitable for residential properties, commercial sites, schools, estates, highways, parks, and public spaces where there is a duty of care to manage tree-related risk responsibly. Reports may include detailed observations, risk calculations, recommendations for remedial works or further investigation, and ongoing management advice tailored to the site and level of risk identified.

QTRA assessments can support landowners, property managers, local authorities, insurers, and developers by providing clear and professionally documented evidence of tree risk management, helping demonstrate compliance with legal responsibilities and recognised industry guidance.