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QTRA Publications

This page contains downloadable documents either published by Quantified Tree Risk Assessment Limited or presented by us and published elsewhere.

The original 2005 Journal of Arboriculture paper 'Quantified Tree Risk Assessment used in the management of amenity trees' is available here, but please be aware that the method has evolved and is now substantially different to that which is set out in this original paper.  For the current method, you should refer to the Quantified Tree Risk Assessment Practice Note, which is also available on this page.

Over the years, we have commented on court legal cases and public consultations pertaining to the management of risks from trees.  These documents are mainly to be found on this page, but where they relate to a legal case, our comments are to be found on the 'Case Law' page along with the associated legal documents.

Quantified Tree Risk Assessment Practice Note - Version 5.2.1

The Quantified Tree Risk Assessment Practice Note is a technical summary of the QTRA method as it is currently practiced and includes guidance on how risk assessments can inform the management of risks from falling trees. 

Version 5 of the QTRA method is a substantial revision of the method with different risk outputs and new advice on how the QTRA risk of harm can inform management decisions. All tree managers using Quantified Tree Risk Assessments to inform the management of risks from falling trees should be familiar with this document, which can be downloaded here and distributed freely.

Download a country specific Version 5.2.1 of the Practice Note to provide your clients and tree managers with an overview of the QTRA method and advice on how it can inform their risk decision making.

Quantified Tree Risk Assessment - a non-technical summary

A short, non-technical description of the Quantified Tree Risk Assessment method and how to use the output of a QTRA.

Ellison,M. J. 2005. The Quantified Tree Risk Assessment System.
Arborist News. International Society of Arboriculture, Savoy, Illinois. 14:4 19-25
Ellison, M. J. 2004. Quantified Tree Risk Assessment System
Treeline Magazine. International Society of Arboriculture UK/I Chapter, Wednesbury,England. 14:4 19-25
The Quantified Tree Risk Assessment (QTRA) System A New Approach to Tree Safety Management

Published in the Australian arboriculture trade magazine 'Arborage' in 2006.

QTRA Ltd. response to the consultation draft 'Bringing Common Sense to Tree Management'

Quantified Tree Risk Assessment Ltd. received no acknowledgement of this letter.

QTRA Ltd. response to BSI consultation 'BS8516:2008 Recommendations for Tree Inspection

Comments on the consultation draft of British Standard BS 8516:2008 - Recommendations for tree inspection, which were submitted to BSI by Mike Ellison on behalf of Quantified Tree Risk Assessment Ltd.

The comments are in the form of a letter followed by tabulated comments on each clause of the Standard as submitted through the consultation mechanism on the BSI website.

What is Tree Failure Risk Assessment?

A paper presented to the TreeNet Symposium in Adelaide, South Australia in September 2007.


Quantified Tree Risk Assessment Used in the Management of Amenity Trees


Miscellaneous Documents from Quantified Tree Risk Assessment Ltd.


Quantified Tree Risk Assessment Newsletter - Past Editions