TPZ| SRZ| AS4970-2009 Online Calculator

Eric Frei · 14th February 2010, 10:45 PM

Calculating the TPZs and SRZs will be quick and easy with this new online calculator.

It's ready, tested, accurate and free for you to use.

Also I have uncovered a huge error in AS4970, that's in the next post. Beware using the Standard's diagram/graph ... it's way wrong!

Online Calculator for TPZs and SRZs as per AS4970-2009

Eric Frei · 16th February 2010, 07:00 PM

Interesting. There's a serious error in the Standard perhaps.

The formula for the SRZ is SRZ Radius = (D * 50) ^.42* .64

Here's the graph, I made lines so you can get the answer easier.

Now if you look at the graph with a 1.4m stem dia the answer is around 4.5m

But you get your calculator out and it's 3.81m

So I try another number, 0.8m stem dia and the graph reckons around 3.6m but get your calculator out and I get 3.01m

Eric Frei · 17th February 2010, 03:09 PM

I just received confirmation from Standards Australia about the error and an ammendment is due out soon.

Quote:

Dear Eric

Many thanks for your email and the concern you have raised.

This has already been brought to our attention and we are in the process
of issuing a correction amendment.

Kind Regards

Eric Frei · 7th April 2010, 09:59 PM

Just letting you know that an addition has been made to the calculator.

You can now also calculate the area lost to an intrusion, could be a retaining wall, or concrete driveway, even a building.

You simply enter the known radius of the TPZ and the distance that the intrusion is from the edge of the TPZ.

Eric Frei · 15th April 2010, 08:32 PM

Quote:

Originally Posted by Ekka

Interesting. There's a serious error in the Standard perhaps.

The formula for the SRZ is SRZ Radius = (D * 50) ^.42* .64

Here's the graph, I made lines so you can get the answer easier.

Now if you look at the graph with a 1.4m stem dia the answer is around 4.5m

But you get your calculator out and it's 3.81m

So I try another number, 0.8m stem dia and the graph reckons around 3.6m but get your calculator out and I get 3.01m

Quote:

Originally Posted by Ekka

I just received confirmation from Standards Australia about the error and an ammendment is due out soon.

Please note:- An amendment has been issued 26 March 2010 for the graph.

It is available as a free download (you have to be logged in to get it though) here.

AS 4970-2009/Amdt 1-2010 Protection of trees on development sites

It's good to see they ruled it up similar to the way I ruled it up, also it appears to be accurate now. Better still, use the online calculator.

ARWadoo · 18th April 2010, 02:56 AM

Thank U Ekka for the corrected version of the formulae.I would like to know the details of the parameters considered in derivation of the equation for TPZ and SRZ.
I thank u again for the concern u have shown for my absence from the discussion fora.Infact I was not feeling well for some time . I am better now .
with regards
AR

Eric Frei · 18th April 2010, 10:55 AM

The TPZ is basically 12 x DBH as a radius, maximum is 15m radius, minimum is 2m

The SRZ is a littel weird to work out, formula is shown in the amended picture right at the bottom. The formula remained the same it was the graph that was wrong.

Eric Frei · 28th April 2010, 02:16 PM

I have added a calculator to the same page that can work out what the combined DBH is of multiple stems.

If you have more than 4 stems you simply work out the answer 4 stems, add that answer to one of the input boxes and keep going, and so on, until you have the combined answer ..... so in essence it's unlimited how many stems the tree has.

Eric Frei · 26th June 2011, 09:53 AM

Interesting to find that SRZ calculation gets to a point where the SRZ is actually less than the diameter measurement for it. At 7.88m it is equal. If you ever get a tree that big at the base.

ARWadoo · 26th June 2011, 05:28 PM

Quote:

Originally Posted by Eric Frei

Interesting to find that SRZ calculation gets to a point where the SRZ is actually less than the diameter measurement for it. At 7.88m it is equal. If you ever get a tree that big at the base.

Thank u Eric. Infact i had requested Ashwin as per the provided link to clarify the issue.He has not sofar responded.
Thank u for the info
AR

Eric Frei · 1st January 2012, 11:03 AM

Download the free Android App for the AS4970 Calculator which includes all web calculator tools as listed below.

Online Calculator for TPZs and SRZs as per AS4970-2009

Tree surface area and tree volume calculator

Revised Burnley Method Tree Valuation Online Calculator

ARWadoo · 2nd January 2012, 01:57 PM

Hi Eric
Human intervention for economic development leads to irrecoverable shock of trees when correct distance is not maintained from the tree to build up/filled up area.The work done to evolve the formulae is important to save the environment from ignorant Development managing authorities
Enclosed is the photograph showing devastation of the sylvan beauty by ignoring tree root zone norms
AR

14th February 2010, 10:45 PM	#1
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	TPZ\| SRZ\| AS4970-2009 Online Calculator Calculating the TPZs and SRZs will be quick and easy with this new online calculator. It's ready, tested, accurate and free for you to use. Also I have uncovered a huge error in AS4970, that's in the next post. Beware using the Standard's diagram/graph ... it's way wrong! Online Calculator for TPZs and SRZs as per AS4970-2009 __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

16th February 2010, 07:00 PM	#2
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	Re: TPZ\| SRZ\| AS4970-2009 Online Calculator Interesting. There's a serious error in the Standard perhaps. The formula for the SRZ is SRZ Radius = (D * 50) ^.42* .64 Here's the graph, I made lines so you can get the answer easier. Now if you look at the graph with a 1.4m stem dia the answer is around 4.5m But you get your calculator out and it's 3.81m So I try another number, 0.8m stem dia and the graph reckons around 3.6m but get your calculator out and I get 3.01m __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

7th April 2010, 09:59 PM	#4
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	Calculating segments Just letting you know that an addition has been made to the calculator. You can now also calculate the area lost to an intrusion, could be a retaining wall, or concrete driveway, even a building. You simply enter the known radius of the TPZ and the distance that the intrusion is from the edge of the TPZ. Attached Thumbnails __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

18th April 2010, 02:56 AM	#6
ARWadoo Semi-mature vigorous tree Join Date: Jan 2010 Location: J&K State India Posts: 59	Re: TPZ\| SRZ\| AS4970-2009 Online Calculator Thank U Ekka for the corrected version of the formulae.I would like to know the details of the parameters considered in derivation of the equation for TPZ and SRZ. I thank u again for the concern u have shown for my absence from the discussion fora.Infact I was not feeling well for some time . I am better now . with regards AR

18th April 2010, 10:55 AM	#7
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	Re: TPZ\| SRZ\| AS4970-2009 Online Calculator The TPZ is basically 12 x DBH as a radius, maximum is 15m radius, minimum is 2m The SRZ is a littel weird to work out, formula is shown in the amended picture right at the bottom. The formula remained the same it was the graph that was wrong. __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

28th April 2010, 02:16 PM	#8
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	Multiple stems\| trunks\| leaders DBH calculator added I have added a calculator to the same page that can work out what the combined DBH is of multiple stems. If you have more than 4 stems you simply work out the answer 4 stems, add that answer to one of the input boxes and keep going, and so on, until you have the combined answer ..... so in essence it's unlimited how many stems the tree has. __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

26th June 2011, 09:53 AM	#9
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	Re: TPZ\| SRZ\| AS4970-2009 Online Calculator Interesting to find that SRZ calculation gets to a point where the SRZ is actually less than the diameter measurement for it. At 7.88m it is equal. If you ever get a tree that big at the base. __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

1st January 2012, 11:03 AM	#11
Eric Frei Admin - Razor sharp and independent 2 X Diploma Level 5 qualified arborist Join Date: Jan 2007 Location: Brisbane Posts: 12,820	Re: TPZ\| SRZ\| AS4970-2009 Online Calculator Download the free Android App for the AS4970 Calculator which includes all web calculator tools as listed below. Online Calculator for TPZs and SRZs as per AS4970-2009 Tree surface area and tree volume calculator Revised Burnley Method Tree Valuation Online Calculator __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

2nd January 2012, 01:57 PM	#12
ARWadoo Semi-mature vigorous tree Join Date: Jan 2010 Location: J&K State India Posts: 59	Re: TPZ\| SRZ\| AS4970-2009 Online Calculator Hi Eric Human intervention for economic development leads to irrecoverable shock of trees when correct distance is not maintained from the tree to build up/filled up area.The work done to evolve the formulae is important to save the environment from ignorant Development managing authorities Enclosed is the photograph showing devastation of the sylvan beauty by ignoring tree root zone norms AR Attached Thumbnails

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