Risk versus Consequence Decisions

[Frax]

In a previous life I was involved in Project Management. No lives in this case were ever at risk. Just someone else's dollars. But I've adapted an idea central to PM technique in tree work. It's a risk/consequence matrix, and inside the matrix grid are mitigating strategies.



Risk_Consequence Matrix by altacal, on Flickr

Experienced arbs perform these decisions without needing to resort to a diagram but its a useful tool anyway, for teaching and as a way of articulating decision-making to those who are new.

My example is just a general one without reference to a particular situation, but you could draw up a specific one for, say a removal in tight quarters, removal of a hazard tree, and even climbing safety, just for examples.

For example, say falling a tree where there are targets. If the faller is experienced then perhaps the RISK of failure is low. But if there is a house that could be hit by a bad fall, then the CONSEQUENCE of failure is still high. It would be over in the red zone for me. Would you have a mitigating strategy? I would. I would install a rope maybe. Or maybe take the top off first. Examples only in an imaginary situation.

Or, conversely, a medium sized 'cut and chuck' removal where the only serious target is a decaying fence right below the tree. There may be a high probability that limbs could fall and hit the fence and maybe put a nick in it at worse. Probability of failure moderate, but consequences of failure unimportant. Perhaps you just rely on your cutting skills in this case to get the job efficiently done - so you are in the top left of the matrix.. But maybe its a new fence. There is a moderate probablity the fence could get damaged. Maybe you install a rigging rope to be sure. Easy. Not overdone but reduces the oops factor.

You could apply this to safety decisions too. You are using SRT and would prefer a basal tie in. You are rec climbing with experienced partners. Probability of failure low. Consequences high. You install a back-up. But maybe its at work. Is the crew new? Is there a possibility your anchor could be compromized by brush dragging and saw use on the ground? Consequences of failure still extreme. Probability of failure moderate. How will you mitigate? Maybe deciding to go with a tip tie in.

I've gone on long enough. Is this useful to anyone? I realize its second nature to experienced pros, but could it be useful for training?

 

[Tucker943]

It's very useful. But vague. Which makes sense because there are far too many variables in our work.

 

[bonner1040]

Mark Bridge spoke on a similar topic:

http://www.treebuzz.com/pdf/1105_Risk.pdf

I think it has a place in larger companies, but honestly it would be to mitigate liability more than anything else. A large company provides the tool to its employees and then when something goes wrong they post-evaluate the situation with the tool, determine it was a 'red' or 'black' scenario and then maintain that the employee had the resources to determine that it should not have been attempted. Its sad but thats how the world works it seems.

 

[Frax]

It's very useful. But vague. Which makes sense because there are far too many variables in our work.

Vague in my example certainly. You could fill it in for your situation and your own risk tolerance.

 

[Tucker943]

You are right.

 

[RopeArmour]

Looks good.
Clears the thought process for a better decision.

Consequence doesn't sound like fun. I prefer a reward.
Like gettin home to a beer an hour earlier.