An oldie but a goodie: one of my greatest honours: banned from a chainsaw website
MEDIA RELEASE
Newcastle City Council can’t say the Laman Street trees are unsafe:
NO risk assessment is current (more…)
Posts Tagged ‘QTRA’
Media release: risk assessments out of date: 27.1.2012
January 27, 2012Mike Ellison responds to Newcastle City Council 20.1.2012
January 20, 2012
I am ashamed to say that once again my Council has treated an eminent expert shabbily.
As I said at the Fig Forum, there’s nothing to be gained and quite a bit to lose for arboricultural and risk experts to help Newcastle people try to preserve the Laman St trees.
I’m extremely grateful that such knowledgeable and respected experts as Mike Ellison have given us their time and advice.
I should not have been surprised that within the blink of an eye an internal memo critiquing Mr Ellison’s work appeared. (more…)
Mike Ellison’s report 15.1.2012
January 15, 2012
How fantastic it is to receive Mike Ellison’s report on Laman Street. (more…)
Herald interview with Mike Ellison 30.12.2011
December 30, 2011
Mike Ellison interrupted his visit to Laman Street today to talk to the media. (more…)
Media release – Mike Ellison 28.12.2011
December 28, 2011
This is the media release we sent out yesterday about the visit to Newcastle by the developer of Quantified tree risk assessment , Mike Ellison, sponsored by Save Our Figs.
From the questions I’ve had about this from journalists today, I look forward to stories about his objectivity in the press tomorrow. (more…)
Cyber bits and pieces
July 2, 2011As usual, I’m still obsessing about risk and the definition of tree failure. I couldn’t stand it any more so I sought (more) advice. I do like to able to argue intelligently with my cyber bullies. (more…)
Working Party meeting & Gloves off part 1 23.6.2011
June 24, 2011
Well, I’m almost speechless. Last night (22.6.11) was an emergency meeting of the Laman Street Working Party. Since it’s all about the vibe, I’ll just say that the vibe was mostly pretty irritating.
Almost Speechless 9.12.2010
December 9, 2010
On my way to a meeting this afternoon I took a photo for a friend of these wonderful aerial roots at the western end of Laman Street – that’s the end of the street where the trees have so far escaped the beady eye of the QTRA assessor. (more…)
Judgement Reserved – we wait 18.10.10
October 18, 2010
Laman Street’s figs are safe for now as Judge Briscoe in the Land and Environment Court has reserved his decision. Until this is handed down, the injunction remains and council cannot fell the trees. (more…)
Darby Street Fair 10.10.10
October 10, 2010
The Darby Street fair was on today, with crowds of people listening to music and eating lovely food in our restaurant strip just around the corner from the Laman Street figs.
I think it’s an annual event, but living nearby I can tell you it feels a lot more frequent than that. What did I read just today? The days drag but the years fly by. Anyway, it was a great spot for a few of us to man a possie/pozzie (how does one spell that?) just outside the pub to ask people to sign our petition. We were up to 6500 in total a week ago so it should be almost 7000 by now. I wonder what the record is for a Newcastle issue? And still be unsuccessful?
The wind was a bit of a nuisance and it rained every now and again but that’s probably not a bad thing – it must have sent some punters home early instead of encouraging then to keep drinking. Which reminds me that one supporter made the comment that binge drinking leading to violence is a much bigger risk in Newcastle than Our Fig Trees. It’s been a fantastic thing for everyone (except a number of hotel owners) that hotels lock people in and out after 1am now. Violence has dropped impressively. What a shame this hasn’t been an impressive enough trial to convince our state Premier to encourage this elsewhere.
Talk of risk reminded me of a conversation between a local arborist and Mark Hartley (the experienced arborist who did a peer review for us of the council’s arborist reports). An expert with local knowledge gave Mr Hartley some information regarding the frequency of fig tree failures over a decade or so. These figures make a difference to the ‘probability of failure’ used in quantified tree risk assessment (QTRA).
‘… on page 9 [of your peer review], you conservatively estimated the risk of fig tree failure at 1:500 and I think that is a little out. With the benefit of local knowledge I can state that I have personally witnessed at least 4 entire tree failures in Newcastle over the last 10 years (only Hill’s figs) including the Pasha Bulker storm event, and 2 catastrophic failures of the majority of the canopy that would have been included in the same class because of the size of the part, although the nature of the failure cause was different. There are 1200 Figs left in Newcastle of a mature size.
So 6 large or complete failures over a 10 year period out of approximately 1200 trees, what would that make the probability of failure? …Would that increase or decrease the outcome of the probability?’
To which Mr Hartley replied:
…Based on your data in 12,000 tree years (10 x 1,200) there have been 6 failures which means a rate of failure has been 1 in 2000. I have estimated the Probability of Failure to be 4 times higher than those records indicate. (…there is some reason to be [conservative]
This means that the trees outside the gallery would need to be 20 times more likely to fail than the average fig tree in council’s care. It also means that the least conservative estimate for the probability of failure (PoF) provided by the council’s experts is 20,000% out….
In addition there is some evidence to suggest that root severance contributed to at least two of the failures. If these are eliminated then the failure rate due to defects alone is 1 in 3,000. Furthermore, the trees outside the gallery have all been assessed as being free from the significant included stem structure that resulted in the two structural failures … whilst limb failure is possible, loss of large portions of the tree is very unlikely.
If these two structural failures are eliminated then the rate of failure has been 1 in 6,000 This is close to the Probability of Failure of 1 in 5,000 that I said I believe can be achieved with light reduction and thinning.
This means that the Laman street trees would need to be 600 times more likely to fail than the average tree without cut roots and significant structural defects in the trunks in order to achieve the Probability of Failure adopted by [one of council’s experts] and 800 times more likely when considering [another].
Isn’t it nice to see written down by experts why you felt so safe under those trees? Home
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