QTRA n tree risks management with oz

JayJay · 2nd August 2011, 09:00 PM

Hi members of the forum,

In this risk adverse world many risk matrix’s are being presented within the arboricultural industry such as QTRA.

QTRA - Does size matter or do only large sections of a tree fall? ........ and what is the value of life down under? 1/10,000.00 ???????????????

Well respected UK Arborist Jeremy Barrell recently presented at ISA Sydney and outlined his concerns with the QTRA model. PDF attached

I have attached my companies risk matrix for adoption or scrutiny which has been developed with risk managers using information and techniques from nationally/internationally recognised tree assessment systems and then applying that information to align with the International standard AS/NZS ISO 31000:2009 Risk Management – Principles and Guidelines.

I look forward to your comments.

JJ

Eric Frei · 3rd August 2011, 08:55 PM

Your formula is: [(C x 3) + (L x 2)] x 4 / 100 = risk %

I dare say that formula was to get the number as a percentile. Likely we are used to numbers like that.

So it would be: [(C x 3) + (L x 2)] x 4 = risk %

OK, I'll run some numbers:-
[(5 x 3) + (5 x 2)] x 4 = 100%

How about Failure Almost Certain but consequence lowest:-
[(1 x 3) + (5 x 2)] x 4 = 52%

So when you read the "L" factor you have to keep reading the numbers horizontally for that line and reduce the risk to green or yellow. I dare say it has to be that way because the answer 52 pops up in L2 as moderate risk where as in L5 it is insignificant.

In the Consequence what would you say the financial value ($) of the following terms would be?:-

Significant
Major
Moderate
Minor
Insignificant

Would a tree that could fail at the base and strike a house .... how much damage? Like I might guess damage as $5000, would it differ to say $50,000?

Is there any reason why the formula loads C by 3 and L by 2 and not vice versa?

Eric Frei · 3rd August 2011, 10:05 PM

Oh, I have more, been thinking.

QTRA relies a lot on target occupancy.

How does your idea take into consideration target occupancy. For instance, failure is certain, there is no fixed target but an old path people use. The consequence could be catastrophic but for only a few minutes of the day in peak hour when people use the path to work and back. This is where QTRA varies a lot.

A link to an example

Eric Frei · 6th August 2011, 06:51 PM

Interesting to read about legal principles of proportionality and reasonableness.

Quote:

A common method of prioritizing works has been to quantitatively assess the level of risk and use those figures to create a work priority, with the highest levels of risk being carried out earliest in the management schedule. However, some doubts are emerging about whether a quantitative approach can properly embrace the overarching legal principles of proportionality and reasonableness.
Superficially, quantifying the level of risk by multiplying scores for 1. occupancy (number of targets), 2. size of the tree part that could fail, and 3. the likelihood of failure, is attractive because it seems intuitively right, but a deeper analysis reveals some obvious flaws from such a quantitative approach. The law is concerned with proportionality, i.e. how much will it cost to reduce the risk of harm and how much of a reduction is achieved for that cost. This principle carries with it an obvious implication that cost-effectiveness matters, i.e. where is the best effect for each unit of cost. In the context of proportionality, failing to properly consider cost-effectiveness when prioritizing works could be seen as a significant weakness by the courts and expose duty holders adopting a simplistic quantitative approach to unexpected liability.
More specifically, taking occupancy first, once the threshold for checking has been passed, i.e. there is a level of formal access that warrants a visual check, then the conventional quantitative view is that the more targets there are, the higher the level of risk and the greater the priority for action. Similarly, the reasoning for the size of the part that could fail will be the same, i.e. the bigger the part, the greater the overall risk and so the greater the priority for action. However, my experience in dealing with tree failure incidents is that a significant proportion of people do get killed or severely injured in areas of very low access and by relatively small tree parts, a practical reality that seems at odds with the quantitative theory. Furthermore, when one of these cases finally gets to court, it is inevitable that the principle of proportionality will be applied and, irrespective of the magnitude of the level of risk, if even a very low risk was easy and cheap to address, then cost-effectiveness of action may well trump the level of risk as the primary prioritization criterion.....

..... In terms of modifying present practice, the implications of these practical observations are subtle, but profound. As set out in Figures 9 and 10, occupancy will indicate a threshold for triggering a visual check. However, where a priority for action is required, basing this on a simplistic quantification of the level of risk may be found lacking by courts that will be carefully referencing the legal principle of proportionality, which inevitably makes the cost-effectiveness of remedial action an important consideration. Instead, it seems likely that a priority for action based on the likelihood of failure and the cost to remedy may be a safer route for duty holders. In practice, this means that leaving even small branches with a strong likelihood for failure close to low occupancy locations, i.e. infrequently used footpaths, could leave a duty holder vulnerable to criticism, especially if the cost to reduce or remove the risk was low.

So I suppose to answer my own question about the low use path is the worst case scenario is some-one getting killed or seriously injured if they are below it at the time of the failure. QTRA would lower the number due to occupancy rates but the worst case scenario is death, and the hazard could be removed for $300 on the next round of pruning in the area.

In effect QTRA is gambling with occupancy rates, but if it did happen then you would have to feel pretty bad taking the risk for the small cost of mitigation.

Eric Frei · 13th August 2011, 10:39 AM

Well I have read the standard over and over and I see no reference to 1:10,000 risk of death per annum as being the threshold for acceptable risk.

It would then be an interesting case to see QTRA being defended in court for a fatality or severe injury as it would come under criticism.

-------------------------------------

In Common-law, risk used:

– Amongst a number of uses:
• it is part of the “calculus of negligence”

• It includes

– Magnitude of risk of injury; and
– the probability of it’s occurrence
– Weighed against
» Expense
» Difficulty
» Inconvenience

In OH & S legislation

• Risk management is regularly referred to;

– To paint a picture of a proactive, harm-minimisation
process

– An expectation of the legislation

• Risk is not quantified in any state legislation
• All states use the common law test of:
– “best-practicable means” when assessing the outcomes of the risk management process

-------------------------------

Eric Frei · 17th August 2011, 08:05 AM

Well certainly the value of life varies around the globe.

In Afghanistan none were worth more than $8,000

Even after adjustments for the difference between say America and Afghantistan purchasing power the sums come up that an American life is worth around 144 Afghani lives and a British life is worth around 160 Afghani lives.... who said all lives were created equal eh.

What price an Afghan life? | Peter Singer | Comment is free | guardian.co.uk

Quote:

1 April 2011
What price an Afghan life?

If Nato treated all human life as of equal value when paying compensation it would change the face of the Afghan conflict

How many Afghan lives are worth one British life?

We shrink at that question. If forced to answer, some reply: "All human life is of infinite value." Others cite the Jewish teaching that if you put one human life on one side of a scale, and the rest of the world on the other side, the scale is balanced equally. Most just say that an Afghan life is worth the same as a British life, because all human lives are of equal value. Isn't that what we all believe?

The Ministry of Defence has been paying compensation to Afghans for accidentally killing their children, their brothers and sisters, or their parents, during the fighting in Afghanistan. Thanks to a freedom of information request from the Guardian, we know how much the MoD has paid families when a member has been killed. Here are some examples: daughter hit by shrapnel from air-strike and later died of injuries, $1,000; mother killed during bombing, $5,000; two brothers and two sons killed by hellfire missile strike, $32,000. The variation in the figures is not explained, but in no case was more than $8,000 (about £5,000), paid for the loss of a single life.

Now let's take a look at the value of a British life. The National Institute for Health and Clinical Excellence (Nice) assesses drugs and other medical treatments for cost-effectiveness and recommends whether they should be supplied on the National Health Service. Nice is commendably transparent. No freedom of information requests are needed. Just visit its website for a description of how it decides if a treatment is worth paying for. The key factual question is how much the treatment costs for each quality-adjusted life year, or QALY, gained. A QALY is one year of life of good quality, or its equivalent, which might be a longer period of life of lower quality. The website then tells you that while decisions are made on a case by case basis, "generally … if a treatment costs more than £20,000-30,000 per QALY, then it would not be considered cost effective".

Remember, that sum is per QALY, not per life saved. So if we take the bottom end of this range, Nice recommends that the NHS pay up to four times as much to extend the life of a British citizen by just one year, as the MoD is prepared to pay in compensation for killing a child or young person. That young person could – even allowing for Afghanistan's dismal life expectancy – expect to live another 40 reasonably good-quality years. That suggests an answer to the question with which I started: it takes about 4 x 40, or 160 Afghan lives, to be worth the same as one British life.

But that would not be the right answer, because £5,000 will buy much more in Afghanistan than it would buy in Britain – according to international price comparisons, perhaps four or five times as much. Let's say five times. Even with that adjustment, it is going to take 32 Afghan lives to be worth the same as one British life.

There is nothing unique about Britain in this respect. The Guardian has reported that the US generally pays no more than $2,500 in compensation for the loss of an Afghan life. In contrast, after the terrorist attacks of 11 September 2001, the US government set up a Victim Compensation Fund. The average payment it made to families of victims was $1.8m. Adjusting for purchasing power at a 5:1 ratio suggest that the US regards the life of an American as equivalent to the lives of 144 Afghans.

What would happen if the Nato forces really took seriously the idea of the equal value of all human life? They would then have to compensate Afghans for the civilian deaths and injuries they are causing at the same level as they would compensate their own citizens if, for example, a military exercise went wrong and killed people at home. That would serve three important purposes. First, it would demonstrate to the Afghans that the Nato forces truly respect them as equals. Second, the troops themselves might start to see Afghans as more like them, and have a new respect for the people they are trying to aid. Third, a dramatic increase in the costs of endangering the lives and limbs of civilians might foster a new restraint, because no military force wants to drain its own resources. The result would then be that fewer civilians would be killed – surely a very good thing, both for the civilians themselves, and for winning over the support of Afghans.

So I suppose for QTRA there wouldn't ever be a risk in Afghanistan to mitigate.

I dare say similar for other nations where the monetary value of life is low.

Eric Frei · 18th August 2011, 09:30 AM

QTRA Laman Street Figs Fiasco - YouTube

Eric Frei · 19th August 2011, 11:02 AM

Acts of God, Urban Tree risk Assessment, Treenet.org 2010 Symposium

Martin Norris Tree Risk 2010 Treenet Symposium - YouTube

silent 2035 · 22nd August 2011, 07:55 PM

In review of the last few threads and new to the forum/QTRA thread.

About time an OZ risk version was put forward for discussion!

The first Utube clip makes me laugh as personally I have studied the QTRA ways but have more concerns than answers ..... its a ticking time bomb as UK Arborist J. Barrell explained at the recent conference.

Latest Utube post was a simple and logical explaination. Trees fail in winds greater than 100km .... act of god or not an act of god ???? guess u will have to listen.

I have attached a paper I found from Martin's early works/review of the Arb industry. Having a risk matrix that aligns to Australian Standards makes sense and therefore why do we keep sending $$ to the UK for a model that I believe fails to align with Australian Standards.

It would appear our industry bodies would rather support the work of the UK and fails to reckonise the work of Australian Arborists much like M. Norris studies.

thoughts?

Eric Frei · 22nd August 2011, 09:36 PM

Quote:

Originally Posted by silent 2035

Having a risk matrix that aligns to Australian Standards makes sense and therefore why do we keep sending $$ to the UK for a model that I believe fails to align with Australian Standards.

It would appear our industry bodies would rather support the work of the UK and fails to reckonise the work of Australian Arborists much like M. Norris studies.

thoughts?

I personally feel the orgs have seriously let down the Australian arborists by not using their funds to interrogate the QTRA method. They have the funding to go to actuaries and risk assessors to get it pulled apart before blindly supporting it.

Martin wrote in that excellent PDF:-

Quote:

Most current tree risk industry standards are focused on defect identification; the industry needs to
broaden its focus to encompass the other equally important elements of risk assessments, including
likelihood of failure, target occupancy, magnitude of damage and importantly to have a debate on the
meaning of ‘acceptable risk’.

Assessor Issues

Tree risk assessments are based on the judgement of assessors. Any person purporting to undertake risk
assessments should understand, acknowledge and account for, inherent assessor and model bias, human
error, the underlying methodology and use of definitions. Individual limitations of skill, ability, and
training should be acknowledged. Risk assessors must be able to demonstrate that their assessments
comply with the three elements required of a risk assessment, that of, ‘risk identification,’ ‘risk
analyses’ and ‘risk evaluation’.

The issue is debate, from one particular Sir from AA it is belittling and insulting people .... many simply cannot debate much without getting nasty and insulting. Some also perceive healthy intellectual debate as rebellious and non conforming.

20 August 2011 Mark Hartley (one of the Directors of AA) wrote on that trash USA site:-

Quote:

Frei is so ignorant that he confuses hazard identification with risk assessment. Why would any one attempt to asses the risk of harm without first assessing a tree for defects? Frei shows that he has no knowledge of the difference between hazard and risk.

I am sorry but I truly think he has lost it big time

Also on 2 August 2011 Mark Hartley posted this over there:-

Quote:

He even has a funny YouTube cartoon that shows he is a complete ignoramus when it comes to quantifying risk. He treats hazard identification and risk assessment as though they are the same thing. I dread to think how he handles OH&S. Perhaps he needs to read AS/NZS ISO 31000:2009. He thinks that once you assess a tree with diagnostic equipment that is the end of it all. Again he knows best, after all he is an authority on the subject ... if only those stupid professors would listen to him.

And you wonder why the industry is the way it is, time for a change.

This is Australia's largest forum where tree discussion should be, but you can see the calibre of many when it comes to healthy discussion.... it is not possible, hence why we kicked his troll ass out of here, maybe 5 times or so as he kept coming back. Then we got inundated by other "friends" of his, their contribution duly noted, some of it removed and their asses banned to.

The common denominator is they cannot go hard on the topic and go hard on the people, the people who don't agree with them. To them the internet is still a toy and place where you go to bully and be a keyboard hero.

It will all change soon

....

Seeking Interest for New Arboricultural Association

Darrell Mcleod · 22nd August 2011, 11:08 PM

One would think lots of consulting arborists would be very interested in this thread

I think this is true

Quote:

Originally Posted by Eric Frei

I personally feel the orgs have seriously let down the Australian arborists by not using their funds to interrogate the QTRA method. They have the funding to go to actuaries and risk assessors to get it pulled apart before blindly supporting it.

Quote:

Originally Posted by silent 2035

Having a risk matrix that aligns to Australian Standards makes sense and therefore why do we keep sending $$ to the UK for a model that I believe fails to align with Australian Standards.

This is why we need a new Australian Organisation with the courage and purpose to pursue, dicuss, develop and implement values that can be peer reviewed and revised as needed

It MUST start somewhere

Pity these sorts of comments have to be made - but true

Quote:

Originally Posted by Eric

This is Australia's largest forum where tree discussion should be, but you can see the calibre of many when it comes to healthy discussion

Therefore it is up to current org members and others to see where the orgs have failed and become actively involved with either learning or sharing to produce something far better

Eric Frei · 22nd August 2011, 11:23 PM

There's a culture where they run back to their own little huddle groups of like minded people and back-stab those who do not fit in with them.

You Tube

Eric Frei · 23rd August 2011, 05:56 PM

Here's a real case .... adds a twist to the whole responsibility thing. I am not discussing about the costs but the bolded part about denying responsibility.

Fallen tree proves costly - Local News - News - General - St George & Sutherland Shire Leader

Quote:

Fallen tree proves costly
23 Aug, 2011
ROY Delfino is angry that he has had to foot the bill for a tree that fell on council property taking down power lines leading to his house.

Mr Delfino, a retired musician who lives at Oatley but is also a Sutherland Shire ratepayer, found that a mature tree had fallen on the council reserve opposite his investment property in Auburn Street, Sutherland on May 4, bringing down four power lines.

‘‘I rang the insurance company and organised to have the wires repaired as soon as possible,’’ he said.

‘‘There are kids living in the area and you can’t have live power lines down.

‘‘Now the insurance company has put up my premium and charged me $300 excess even though the tree was on council property.

‘‘I’ve paid it but I rang the the council and asked for a $300 rebate because the tree is on their property.

‘‘The council advised me that they are not responsible and denied any claim for reimbursement of costs.’’

A letter to Mr Delfino from a spokesman for Sutherland Shire Council’s general manager John Rayner said: ‘‘While it is most unfortunate that the damage has occurred to your property, council wishes to advise that it is not responsible for this damage.

‘‘As of 2004, the council adopted a policy to deny claims
in respect of council failing to take precautions against a risk of harm (defined as personal injury, death, property damage or economic

loss — Section 5 of the Civil Liability Act 2002) arising from falling trees, from falling tree branches

or encroachment of tree roots.’’

Mr Delfino said the council response was very unfair.

‘‘It’s not the money,’’ he said. ‘‘It’s the principle.

‘‘If a tree on my property fell and damaged their property I would be liable. It seems to be one set of rules for them and another for the rest of us.’’

A Sutherland Shire Council spokeswoman said the general manager stood by his decision as outlined in his letter that stipulated that the the council was not liable for falling trees or falling branches.

silent 2035 · 24th August 2011, 10:31 PM

Why are they not liable .... is it because they have tooooooooooo many trees and not enough resources to inspect the tree?

Just found this but yet to read about Council's liability for street tree ''2008''

JayJay · 25th August 2011, 06:59 AM

Eric,

Sorry about the delay in answering your questions posted in early August and to other tree world members following this thread.

The $$ figure was explored but not used and would be an interesting debate given money talks. We looked in more detail into the size of part and location - being land parcel type and road hierarchy. In summary these additions (land usage etc) did not really work within the Australian Standards (5 x 5) configuration BUT I am not saying they can't either BUT possible could be included as an additional part of the assessment (before or after).

Martin Norris in my eyes would have some value to the debate and its great to see the push for an Australian version and Martin's work displayed on the forum as I believe the QTRA is not the answer for Australia presently. The wheel formation is commonly used by engineers .... is it our love of gadgets that makes it (QTRA) appealing ... please enlighten me any QTRA user
here is Australia.

The Sutherland news paper article was interesting and understanding Council's position in relation to risk is of interest I believe.

Silent 2035 - is this a question or statement ... either way interest point re resources and capability.

Eric Frei · 25th August 2011, 06:37 PM

In Martin's paper there's some tabulated risks as below:-

I want to look at the ones that are more accidental rather than health, so starting from the 1:7000 for travelling by motor vehicle.

Now I do not know how those numbers are derived, whether that is a simple division of deaths per drivers per annum etc but we all know within those numbers are demographics that place some at greater risk than others.

The difference is that when I am driving a car I know that risk is high, I know that I am more stressed than lying in bed at home. I know that the car also has safety features like seat belts, side intrusion bars, bumper bars and a collapsible shell, air bags, anti-lock brakes for some etc etc. The car is loaded with safety features but even then I am more stressed and it is suggested that you take a rest every 2 hours. If in all fairness I am expected to live at that level of observation, stress, worry and concentration to accept trees then that is an absurd expectation, especially around my home.

Dividing the number of trees by injuries to get a risk is distorted because it fails to consider all the removals and other tree work to have a low incident rate.

I wonder what the spend is nationally by all councils on tree removals and pruning? It would be fair to say then that all those injuries came after that amount of money was spent on mitigating hazards. So to use that post tree care number to apply a pre tree care rating is illogical.

I hope I am making sense. In other words it is because we deadwood trees that more people have not been hit by falling deadwood. But to use a figure of 1:10,000 to not take action will result in more injuries as the deadwood will remain in the trees to shed naturally. Imagine a single tree with deadwood, the number says not to worry about it, then imagine an avenue of trees, individually they have a 1:10,000 risk but now to the pedestrian who has to walk beneath them for 5 minutes ......

Eric Frei · 25th August 2011, 08:14 PM

If it is foreseeable that design strength will be exceeded then failure (when it is exceeded) is not considered an Act of God.

Many tree failures occur when wind strength is greater than 80km/h.

I will soon post up the maximum wind speed recorded per month for the last 10 years in Brisbane. I have to wait for the BOM report as it was a special request.

Another fact to consider is councils enforcing tree protection orders on large trees in close proximity to homes. The Gap storm of 2008 here in Brisbane final cost was around $309miilion.

So people are unable to remove large trees, and regardless of those trees being "healthy and sound" they can fail, and did. There are species more suitable than others for urban environments and the consequences of a 30' paperbark tree failing vs a 120' gum tree are vastly different. What happens there with councils enforcing people to live with a higher risk?

Eric Frei · 31st August 2011, 06:40 PM

Quote:

Originally Posted by Eric Frei

I will soon post up the maximum wind speed recorded per month for the last 10 years in Brisbane. I have to wait for the BOM report as it was a special request.

All measurements were taken at Brisbane Airport. Zip file attached.

Only in 3 years out of the last 10 years did we not get a gust above 80kmh

Eric Frei · 30th October 2011, 11:44 AM

On 13 October 2011 in the afternoon a driver seeking refuge from a hail storm was killed when a tree fell on his car.

From BOM records at Archerfield (closest to site) the maximum wind gust recorded was a SE gust 61km/h at 15.37hours (3.37pm) which coincides to the approximate time of the incident.

The tree fell at 90 degrees to the direction of the wind gust, the tree fell to the SW and fell exactly to the lean of the tree. Often storms roll in from the SW (I live here) so this tree failed at either 90 degrees to recorded gusts or head on into the wind.

What actually happened in this set of circumstances is target occupancy increased momentarily to 100% as the vehicle parked beneath the tree. Often an assumption is made that target occupancy decreases in adverse conditions.

The details and video about the Johnson road Hillcrest fatality is here.

3rd August 2011, 08:55 PM	#2
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: QTRA n tree risks management with oz Your formula is: [(C x 3) + (L x 2)] x 4 / 100 = risk % I dare say that formula was to get the number as a percentile. Likely we are used to numbers like that. So it would be: [(C x 3) + (L x 2)] x 4 = risk % OK, I'll run some numbers:- [(5 x 3) + (5 x 2)] x 4 = 100% How about Failure Almost Certain but consequence lowest:- [(1 x 3) + (5 x 2)] x 4 = 52% So when you read the "L" factor you have to keep reading the numbers horizontally for that line and reduce the risk to green or yellow. I dare say it has to be that way because the answer 52 pops up in L2 as moderate risk where as in L5 it is insignificant. In the Consequence what would you say the financial value ($) of the following terms would be?:- Significant Major Moderate Minor Insignificant Would a tree that could fail at the base and strike a house .... how much damage? Like I might guess damage as $5000, would it differ to say $50,000? Is there any reason why the formula loads C by 3 and L by 2 and not vice versa? __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

3rd August 2011, 10:05 PM	#3
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: QTRA n tree risks management with oz Oh, I have more, been thinking. QTRA relies a lot on target occupancy. How does your idea take into consideration target occupancy. For instance, failure is certain, there is no fixed target but an old path people use. The consequence could be catastrophic but for only a few minutes of the day in peak hour when people use the path to work and back. This is where QTRA varies a lot. A link to an example __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

13th August 2011, 10:39 AM	#5
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: QTRA n tree risks management with oz Well I have read the standard over and over and I see no reference to 1:10,000 risk of death per annum as being the threshold for acceptable risk. It would then be an interesting case to see QTRA being defended in court for a fatality or severe injury as it would come under criticism. ------------------------------------- In Common-law, risk used: – Amongst a number of uses: • it is part of the “calculus of negligence” • It includes – Magnitude of risk of injury; and – the probability of it’s occurrence – Weighed against » Expense » Difficulty » Inconvenience In OH & S legislation • Risk management is regularly referred to; – To paint a picture of a proactive, harm-minimisation process – An expectation of the legislation • Risk is not quantified in any state legislation • All states use the common law test of: – “best-practicable means” when assessing the outcomes of the risk management process ------------------------------- __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

25th August 2011, 06:59 AM	#15
JayJay Sappling Join Date: Aug 2011 Location: Australia Posts: 8	Re: QTRA n tree risks management with oz Eric, Sorry about the delay in answering your questions posted in early August and to other tree world members following this thread. The $$ figure was explored but not used and would be an interesting debate given money talks. We looked in more detail into the size of part and location - being land parcel type and road hierarchy. In summary these additions (land usage etc) did not really work within the Australian Standards (5 x 5) configuration BUT I am not saying they can't either BUT possible could be included as an additional part of the assessment (before or after). Martin Norris in my eyes would have some value to the debate and its great to see the push for an Australian version and Martin's work displayed on the forum as I believe the QTRA is not the answer for Australia presently. The wheel formation is commonly used by engineers .... is it our love of gadgets that makes it (QTRA) appealing ... please enlighten me any QTRA user here is Australia. The Sutherland news paper article was interesting and understanding Council's position in relation to risk is of interest I believe. Silent 2035 - is this a question or statement ... either way interest point re resources and capability.

25th August 2011, 06:37 PM	#16
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: QTRA n tree risks management with oz In Martin's paper there's some tabulated risks as below:- I want to look at the ones that are more accidental rather than health, so starting from the 1:7000 for travelling by motor vehicle. Now I do not know how those numbers are derived, whether that is a simple division of deaths per drivers per annum etc but we all know within those numbers are demographics that place some at greater risk than others. The difference is that when I am driving a car I know that risk is high, I know that I am more stressed than lying in bed at home. I know that the car also has safety features like seat belts, side intrusion bars, bumper bars and a collapsible shell, air bags, anti-lock brakes for some etc etc. The car is loaded with safety features but even then I am more stressed and it is suggested that you take a rest every 2 hours. If in all fairness I am expected to live at that level of observation, stress, worry and concentration to accept trees then that is an absurd expectation, especially around my home. Dividing the number of trees by injuries to get a risk is distorted because it fails to consider all the removals and other tree work to have a low incident rate. I wonder what the spend is nationally by all councils on tree removals and pruning? It would be fair to say then that all those injuries came after that amount of money was spent on mitigating hazards. So to use that post tree care number to apply a pre tree care rating is illogical. I hope I am making sense. In other words it is because we deadwood trees that more people have not been hit by falling deadwood. But to use a figure of 1:10,000 to not take action will result in more injuries as the deadwood will remain in the trees to shed naturally. Imagine a single tree with deadwood, the number says not to worry about it, then imagine an avenue of trees, individually they have a 1:10,000 risk but now to the pedestrian who has to walk beneath them for 5 minutes ...... Attached Thumbnails __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

25th August 2011, 08:14 PM	#17
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: QTRA n tree risks management with oz If it is foreseeable that design strength will be exceeded then failure (when it is exceeded) is not considered an Act of God. Many tree failures occur when wind strength is greater than 80km/h. I will soon post up the maximum wind speed recorded per month for the last 10 years in Brisbane. I have to wait for the BOM report as it was a special request. Another fact to consider is councils enforcing tree protection orders on large trees in close proximity to homes. The Gap storm of 2008 here in Brisbane final cost was around $309miilion. So people are unable to remove large trees, and regardless of those trees being "healthy and sound" they can fail, and did. There are species more suitable than others for urban environments and the consequences of a 30' paperbark tree failing vs a 120' gum tree are vastly different. What happens there with councils enforcing people to live with a higher risk? __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

30th October 2011, 11:44 AM	#19
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: QTRA n tree risks management with oz On 13 October 2011 in the afternoon a driver seeking refuge from a hail storm was killed when a tree fell on his car. From BOM records at Archerfield (closest to site) the maximum wind gust recorded was a SE gust 61km/h at 15.37hours (3.37pm) which coincides to the approximate time of the incident. The tree fell at 90 degrees to the direction of the wind gust, the tree fell to the SW and fell exactly to the lean of the tree. Often storms roll in from the SW (I live here) so this tree failed at either 90 degrees to recorded gusts or head on into the wind. What actually happened in this set of circumstances is target occupancy increased momentarily to 100% as the vehicle parked beneath the tree. Often an assumption is made that target occupancy decreases in adverse conditions. The details and video about the Johnson road Hillcrest fatality is here. __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

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