Any assessment of risk from trees falling should begin with a Tree Risk-Benefit Management Strategy.
Whether you're a Duty Holder or a Risk Assessor, here are 5 valid reasons why the Strategy is your greatest tree risk asset.
1 The Context A Strategy establishes the context (ISO 31000) of the risk universe in which you're working. It sets out your stall by defining your 'risk objectives', and setting out the rules of the game.
2 What you're doing It makes it clear what a Risk Assessor is doing when they're looking at a tree. Why they're doing it. And what the limitations are.
3 The donkey work The Strategy does more than 95% of your risk assessments for you.
4 Underwritten Your insurers will be happy to underwrite you.
5 The truth of the matter The Strategy 'speaks truth to power'.
speaking truth to power
In the extremely unlikely event of an Acceptable or Tolerable risk happening. And a claim is being considered. It's the Strategy that puts you in the best position to disarm an Expert Witness who struggles with risk literacy.
Or regulate a Risk Entrepreneur, who profits by talking up the risk.
The Strategy also gives you defence in depth by speaking truth to Judges, Coroners, and Enforcement Officers.
If you want to know what a Tree Risk-Benefit Management Strategy looks like, we've got a whole bunch of free templates on our Risk Management page.
We know from pedestrian data, the centre of built-up areas have a Likelihood of Occupancy that's so high, on average more than one person is exposed to the risk.
Occupancy is Very High.
We also know from traffic data, the busiest roads have a Likelihood of Occupancy that's so high, on average more than one vehicle is exposed to the risk.
Where we have busy roads next to busy footpaths in towns and cities, we know the combined occupancy of people AND traffic is so high, on average more than one person AND one vehicle is exposed to the risk.
We know other tree risk assessment systems systematically undervalue Very High Occupancy. From the training we’ve delivered, we also know tree risk assessors have been poorly trained to recognise both Very High and High Occupancy.
What all this means is unless you’re using VALID, and have had Likelihood of Occupancy training (it’s really easy once you're calibrated), you’ll be undervaluing the occupancy where it matters most.
If you're undervaluing the occupancy, you'll be undervaluing the risk.
You’ll be undervaluing the risk by at least a whopping factor of x10 or x100.
A 1:1M risk might be as high as 1:10K.
A Low Risk might be a High Risk.
If you've heard of Daniel Kahneman, you'll likely have read his excellent Thinking Fast & Slow, where he shares his Nobel Prize winning work into behavioural economics. All that fascinating stuff about how ingrained biases often have reasonably foreseeable impacts on our decision making.
His most recent interest has been a collaboration with Oliver Sibony and Cass Sunstein, exploring the role of 'Noise' in decision making.
Noise is the significant variability in decisions you get where there shouldn't be any. Such as when Doctors diagnose disease, or when Judges sentence criminals.
Or when Arborists make tree risk assessment decisions.
Earlier this year, More or Less' Tim Harford had a short chat with Daniel Kahneman about how to reduce Noise by practising Decision Hygiene.
https://validtreerisk.help/Noise
If you want to dive into the Decision Hygiene part, it starts at 5.50.
What was eye-opening about this discussion into the benefits of practising Decision Hygiene is that it's embedded in VALID.
Arborists' tree risk assessments are notoriously noisy. Ask 10 Arborists to risk assess a tree and you'll likely get 12 very different decisions.
One of VALID's benefits is we've designed it to reduce this Noise. When it comes to Occupancy and Consequences, consistent and good decision making is so 'quiet' you don't need to be an Arborist to do it well.
In tree risk assessments, we get most Noise with Likelihood of Failure decisions.
When you make your Likelihood of Failure decision in VALID, you're guided to evaluate all the likelihood of failure attributes, independently of each other, before you make a decision.
This VALID approach to Likelihood of Failure decision making is what Daniel Kahneman is calling Decision Hygiene.
Whilst rummaging through some of the UK's dusty Risk & Regulation Advisory Council archives, we strayed across 'A Worrier's Guide to Risk'. David Spiegelhalter (Chair of the Winton Centre for Risk and Evidence Communication at the University of Cambridge) put it together for them in the noughties.
It's a great guide to thinking about risk, some of which applies to trees, on one side of paper - our favourite length for a subject.
This is the one-side-of-paper Summary of our Tree Risk-Benefit Management Strategies.
The history We were first asked to put this together by the Department of State Growth, Tasmanian Government, when they were adopting VALID. It's role was to explain what the Strategy is all about to the departments strategic decision makers. The Summary proved such a useful communication tool, it found its way into the Government Agency template, and we've released it for general use.
How to use the Strategy Summary It works at two levels. If you're a Duty Holder, you can grasp the complete Strategy within the time it takes to take a few sips of tea or coffee. Similarly, if you're an Arborist you can quickly catch the eye of a busy potential client and add value to your service.
Active Assessment - Every 5 years? We think a 5 yearly Active Assessment frequency in Zones of High Confluence is reasonable, proportionate, and reasonably practicable. It's what many Duty Holders are adopting. Here, there's strength in numbers singing from the same hymn sheet if a risk is realised and a claim or enforcement action is being threatened. However, this is a Duty Holders decision. If they have a lower 'risk appetite' and are prepared to spend more money, we don't have a problem with a shorter frequency of Active Assessment. Just edit the PDF or Word Template.
PDF Strategy Summary v9.0.pdf
We have several free Tree Risk-Benefit Management Strategy templates that we've released under a creative commons licence.
You can read all about them on our Risk Management page, and download them as pdf files.
We're happy to share them with you as Word Template .dotx files as well, which makes it easier to customise the few sections that you need to. We've included the fonts that you might not have.
The is the version for a Homeowner. It's the simplest with a Policy and management by Passive Assessment; which is keeping an eye out for Obvious Tree Risk Features you can't help but notice.
PDF Homeowner TRBM Strategy v9.0.pdf
WORD TEMPLATE Homeowner TRBM Strategy v9.0.dotx
Here are the main fonts used in the Tree Risk-Benefit Management Strategies.
Museo 700 Source Sans Pro
Georgia is the body text and that should already be on your computer.
The is the version for a School, College, or University. It's similar to the Landowner one, where the Duty Holder has no trained Arborists as staff.
PDF School TRBM Strategy v9.0.pdf
WORD TEMPLATE School TRBM Strategy v9.0.dotx
The is the Landowner version. The main differences between this and the Government Agency one is there aren't voting stakeholders that you're looking to help understand. So there's no Introduction. There's also no trained Arborist on staff, but this can easily be changed in the Plan.
PDF Landowner TRBM Strategy v9.0.pdf
WORD TEMPLATE Landowner TRBM Strategy v9.0.dotx
Here are the fonts used in the Tree Risk-Benefit Management Strategies that you might not have installed.
The is the Government Agency version, which is the most comprehensive. It's written with Introduction section to explain what the document is about to 'stakeholders'. Also, Arborists are part of the staff, which isn't the case with the other Strategies.
Of course, if the Duty Holder doesn't have Arborists, then it's to edit the document to explain that they'll be hired when necessary. The Landowner Strategy covers this.
PDF Government TRBM Strategy v9.0.pdf
WORD TEMPLATE Government TRBM Strategy v9.0.dotx
Museo 700Source Sans Pro
Here's the new VALID Likelihood of Failure voting card for v2 of the Tree Risk App, which is in development.
If it's new to you, VALID (from where we get our name) gives you 5 chapter headings and 15 subheadings, that can affect a tree's Likelihood of Failure.
When you're carrying out a tree risk assessment, and have got to the tough Likelihood of Failure decision, VALID gives you a structure that guides through the factors you should consider.
At its simplest level, VALID is a checklist of things to think about and you're welcome to this voting card we use in training.
The most important change is:
DEFECT to DECAY We'll finally be rid of any mention of the red DEFECT word in VALID's publications. Those of you who have been there from the beginning will know this has been a quest for some time.
The first subheading under DEFECT is section modulus. That's because if you don't have a grasp of section modulus, and are relying on t/R ratios, you can't make a reasonable decision about the significance of strength loss from decay.
If you're not a Validator, who's been trained to use the Tree Risk App, here's their guide on how they go about using the current version to get to a base rate colour. You should get a sense about how this elegant and sophisticated approach helps you with your likelihood of failure decision making from this.
Likelihood of Failure | Decision Making
Day 2 of Validator tree risk training is all about making robust Likelihood of Failure decisions. If you follow this guide, it's really difficult to get it wrong. If anyone tries to game the risk to get it where they want it to be, it's really obvious where they've got it wrong, and that's what they've done.
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