Risk of Failure Experiment

[Pete Mctree]

0 to 1% actual faliures. I think it has a high potential to fail though which would be what i based my decion upon

[Mark T]

Going on the limited information available and purely for this exercise I would go for the 0 to 10 out of 100 range myself...

 

I would edge towards the upper limit (6 to 8 probably) due to the fact that the tree appears to be in a relatively exposed area, appears to have a relatively large sail area and has cambial wounding to more than 1/3rd of the stem circumference.

 

Details of prevailing wind direction in relation to basal wound would play a part as well.

 

Interesting question that I look forward to watching peoples response to.

Edited February 11, 2009 by Mark T

[Tom D]

<1% I've climbed a few like that. Out of interest how sound was the wood under the exposed area? Was it just a couple of inches of soft sapwood or is it totally gone?

[bob]

i think the poll options are wrong as everyone must be putting 0-10

is it worth changing to 1 2 3 4 5 6 7 8 9 or more

[Amelanchier]

Cheers, Well now we've had some responses, I can lay my cards on the table without fear of prejudicing future results.

 

I'm with Ed - 0. Mainly because I think 1 is too high and 0.25 of a tree out of 100 is a nonsensical answer!

 

Some interesting responses though - perhaps next time I'll divide the poll up a little differently to spread that end of the data. (e.g., 0-1, 2 -4, 5 - 11 12 - 25, 26 - 50, 51 - 100 if appropriate.)

 

When I surveyed it a few years back, I specced a light reduction - mainly because the residents were terrified of it. Not a tree hazard related reason, so I wasn't surprised to hear people suggest action despite the small risk of failure.

 

I was just wondering really where we might draw the line of action, or if we even could statistically on a risk of failure. QTRA suggests we think of failure rates in populations of 10, 100, 1000 and 10000 trees. I struggle with 100.

[Mesterh]

Can you really say that it would have 0% chance of failure within the next 12 months?

I would say it is very low but I wouldnt give 0% of failure within the next 10 minutes of me leaving the site.

[Amelanchier]

Can you really say that it would have 0% chance of failure within the next 12 months?

I would say it is very low but I wouldnt give 0% of failure within the next 10 minutes of me leaving the site.

 

Thats why I phrased the question in the way I did, it's not percentages; it's X no. of trees out of 100. I think the failure rate is less than 1 tree out of 100 but how can less than 1 tree fail? It's either 1 or it isn't!

 

Maybe percentages would be better? I was just trying to mirror the QTRA guidelines.

[stoxs]

But has you have to factor in weather especially wind then it is important to know location in the country and height above sea level, this will all factor towards haw many would fail i guess or because it has with stood the last 10-15 years like this then why would another year make much difference.

 

very interesting subject, i would love to find out more about other defects and potential faliure I.E included bark branch unions and potential faliure rates between species.

 

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[Mesterh]

Oh right soz I understand now.

[Amelanchier]

very interesting subject, i would love to find out more about other defects and potential faliure I.E included bark branch unions and potential faliure rates between species.

 

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!