Risk of Failure Experiment

[Mark T]

Extremely useful exercise... let keep 'em coming! More detail would be good but then we've got to stop somewhere or we'll be submitting reports!

[stoxs]

like it , looked at a beech few months ago with a major lightning strike only 50% max of cambium left for the first 6-7ft , land owner thought the pigeons were eating the leaves because the crown was very thin!

core wood was in good nick and one piece no mush yet.

 

My first reaction was but now knowing a little more about it i think it will last a bit longer, a bigger problem will be the dead branches in the crown falling i think.

 

It is in a private paddock at worst it could flatten a horse!

[educated arborist]

Thats kind of where I'm going with this - trying to work out some repeatable, systematic way in which someone could post a picture and "ask the audience" about the likelihood of failure!

 

failure within how many years, is the defect on south side etc?

I think that most people would want to see such a tree & assess it's whole situation but yep it'l be in between 0-100 lol

 

The last bad winds we had came from the NW (due SW) but, genrally speaking, our prevailing wind direction is SW (due NE) and trees in open surroundings, a 'woodland pasture' type setting tend to develop more and/more substantial roots on the SW side rather sensibly. So when we have strong NE winds trees are more suseptable to failure. Or are they?

 

if only there was real investment in such arboricultural research, i can dream

[Justme]

I dont know about risk assessing trees but in standard biss rick assessments it not just about how likely the thing is to happen but also the consiquences of it happening. So a high risk item that is in an area that would mean no damage happened would get a low rating but a low risk item in a highly populated area would get a high risk rating & would have to have some thing done about it.

 

Its all about risk

likley hood of ocurance

&

possible consiquences

 

Justme

[gibbon]

Whats up with the soil level? Pictures 1 and 3 don't look to unusual but picture 2 looks like the tree has been buried.

 

Have you ever applied Smiley and Fraedrich’s formula for stregnth loss ofopen cavities?

[Amelanchier]

failure within how many years, is the defect on south side etc?

 

For the purposes of this experiment it was failure within 12 months. which is supposed to match up with a fairly average reinspection interval.

[Amelanchier]

I dont know about risk assessing trees but in standard biss rick assessments it not just about how likely the thing is to happen but also the consiquences of it happening. So a high risk item that is in an area that would mean no damage happened would get a low rating but a low risk item in a highly populated area would get a high risk rating & would have to have some thing done about it.

 

Its all about risk

likley hood of ocurance

&

possible consiquences

 

Justme

 

Indeed, but before thinking about the consequences its important to be clear about the likelihood of failure. Otherwise we end up specifying works based on worse case scenarios without thinking about the actual probability of things happening.

[Amelanchier]

Whats up with the soil level? Pictures 1 and 3 don't look to unusual but picture 2 looks like the tree has been buried.

 

Have you ever applied Smiley and Fraedrich’s formula for stregnth loss ofopen cavities?

 

I suspect that the tree was planted within a raised bank and the wound resulted from stem damage and root loss when the bank was removed.

 

I've used smiley and friedrich once or twice - mainly to confirm gut reaction though.

[Justme]

Indeed, but before thinking about the consequences its important to be clear about the likelihood of failure. Otherwise we end up specifying works based on worse case scenarios without thinking about the actual probability of things happening.

 

 

HSE are quite strict on this. Even if the likely ocurance is low if the consiquences are high the "risk" factor is high & some thing must be done.

 

If the consiquences are death (which they are as its in a public area) then even a very low likely hood of happening still merits action (even if that action is just to monitor more often or have a higher spec technical monitoring).

 

 

Justme

[Amelanchier]

HSE are quite strict on this. Even if the likely ocurance is low if the consiquences are high the "risk" factor is high & some thing must be done.

 

If the consiquences are death (which they are as its in a public area) then even a very low likely hood of happening still merits action (even if that action is just to monitor more often or have a higher spec technical monitoring).

 

 

Justme

 

I disagree. What you describe implies that all trees with public access must be inspected. That's not what the HSE say at all (see the attached file!!) or indeed the courts (see the recent judgement on Atkins vs Scott).

 

Anyway - my point is not about action. My point is that we can't even begin to think about action without knowing the likelihood of the event.

 

How would you reconcile your approach with summer branch drop in a public area?

HSE_SIM_Risk_From_Trees.pdf