tree risk assessment


Since our first Quantified Tree Risk Assessment training workshop we have trained over 3500 Registered Users of the method. During this period, feedback from Registered Users along with questions and debate on the QTRA Discussion List has resulted in modification and refinement of the method.  

In 2013 the method was substantially revised. This is the most significant evolution of QTRA since it first appeared in the Journal of Arboriculture in 2005.  It’s involved a lot of very hard work, constructive debates, and behind the scenes number crunching. QTRA is now easier to use, is a more robust method, and makes explaining the Risk of Harm outcomes to clients simple.

training calendar

The main changes are:

  • A redesigned manual calculator and web app.
  • Risks of Harm outputs will now be averages of the combined input ranges rather than an upper value
  • ‘Traffic light’ colour-coded Risk of Harm output ranges to inform clients, which means that most risk management decisions can be made simply on the basis of the colour of an output
  • Improved guidance in the Practice Note and User Manual
  • Improved structure to the assessment process
  • Using an updated approach to the QTRA Walkover Survey to minimise inputs whilst maximising the value of your outputs
  • Calibrating the users Probability of Failure estimates

To bring Registered Users up to date and to address any questions that have arisen through application of QTRA, we initially ran update training. The update training is no longer available, but we are running one-day refresher training beginning in 2005 and would advise all active users of QTRA to attend a refresher at least every 5-years. 


Register your interest in qtra

Register your interest in QTRA training and we will send you an Introductory Information Pack and keep you informed of developments and training events.  When you have registered interest, you can select an event from our Training Calendar and make an online booking.


Our extensive global training courses and workshops will help you become an expert in tree safety and management. Attend one of our training courses to become a registered user of the method.


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