Mapping Software (BS5837 Utility)

[Paul Barton]

OK - misunderstood your post.

[Amelanchier]

 

The above image is taken from the mapmaker site - it alters the shape of the RPA quite nicely, by extending the arc away from the barrier, whilst maintaining the overall area.

 

Notwithstanding the cliff comment, it's uncanny how regularly the RPA is similar to the canopy spread - as in the old rule of thumb for positioning protective fencing.

 

So it does. I should have looked myself!

 

As for the RPA often being a circle, as its a fictional construct relating to our best guess as to where the roots will be, I don't know if I agree with you there. Certainly for open grown trees, I wouldn't dispute your reasoning.

 

All I see are circles in 5837 reports. Mainly I suspect because they are easy to draw. I would suggest that whilst the root system does not mirror the branch system, it is just as likely to be an asymmetric shape much like most trees above ground. Only issue being, we can't see it!

 

We can make good guesses, and in addition to the above constraints, I would expect roots to avoid standing water, compacted areas, rocky outcrops, bonfire sites, rotovated areas, desicatted soil, contaminated soil, areas under known alleopathic trees, etc. All depending on species and age. How about extending RPAs based on a known limit to soil depth???

 

I have a report on my desk to go through next week. I haven't even been out on site but the TCP clearly shows a RPA line through the middle of the Norwich Ring Road. So that's already put me in a defensive mode as its unlikely considering the lush verdent surroundings.

 

Software looks like its worth a punt though. First big job would pay for itself.

[Giles Hill]

Thereby self drawing an rpa effectively... ( because it maintains an area ( m2 ) with no basis in reality) ??

 

The RPA is based on a calculation of 12 x stem dia. So the bigger the stem dia, the bigger the RPA.

 

I'm not sure how they came about the calculation, but it seems to do the job and provide an adequately sized undisturbed area around trees - if applied appropiately.

 

If anything it usually amounts to a larger area than is strictly necessary, but it's best to be safe and all that.

 

It does the job and the only alternative formula for calculating the area is:

 

Random Opinion + Cost of Land + Developer Pressure + Ignorance = Inadequate Protection

[Giles Hill]

So it does. I should have looked myself!

 

As for the RPA often being a circle, as its a fictional construct relating to our best guess as to where the roots will be, I don't know if I agree with you there. Certainly for open grown trees, I wouldn't dispute your reasoning.

 

 

If it's applied to anything other than an open ground tree, it does become rather open to debate, but I think it still does enough - if you're doing something similar to what's shown on the image above - i.e. radiate out from the tree until you meet a barrier, then accommodate the additional area by radiating further where there are no barriers...

 

The thing that gets me sometimes, is when you find trees that appear to have barriers all around them, and the only way to accommodate the BS would be to extend the area to places where roots aren't going to be.

[Amelanchier]

Table 2 of the BS indicates its sources...

 

NOTE The 12× multiplier is based on NJUG 10 [9] and published work by Matheny and Clark [10].

 

where [9] and [10] refer to:-

 

[9] NATIONAL JOINT UTILITIES GROUP (NJUG). Guidelines for the planning, installation and

maintenance of utility services in proximity to trees. Publication number 10. NJUG, April 1995.

 

[10] MATHENY, N. and J. CLARK. Trees and development. A technical guide to preserving trees during land development. 1998. International Society of Arboriculture, Champaign, IL 61826-3129. 184 p.

 

[Amelanchier]

The thing that gets me sometimes, is when you find trees that appear to have barriers all around them, and the only way to accommodate the BS would be to extend the area to places where roots aren't going to be.

 

I wouldn't have a problem if you said that in a report! If you could back it up with solid reasoning and maybe the odd hand dug trial trench, I'd be fine with a reduced RPA.

[Bundle 2]

It seems like a bit of a backward step in some ways as the research that has been gleaned presumably from utilities repeatedly digging up root zones for installetion is somehow inadequately formularised with a recipe in the shape of software for the purposes of expediency.

As it has been said tho', it appears to do enough.

At the end of the day, it will either prove to be a worthwhile tool or not.

Seems like a sensible suggestion to include trench trial detail when/where necessary....Whatever it takes to make it work.

[Giles Hill]

I wouldn't have a problem if you said that in a report! If you could back it up with solid reasoning and maybe the odd hand dug trial trench, I'd be fine with a reduced RPA.

 

I'm always ready to reason things out if I'm asked. I'm using autocad, so TBH it normally starts off as circles. I tend to use the BS as a basis for the calculation - but err on the side of caution, particularly if dealing with very mature trees.

 

Here's one I did earlier...

Red line = fence

Cross hatch = ground protection

Purple = RPA

 

 

I used a preliminary drawing as the basis for asking the architect to shift the house back from the oak on the frontage - I would have had a job agreeing this without the BS to refer to.

 

It's a bit of a squeeze as seems to be the norm nowadays, but I think it's the best fit and the trees shouldn't be compromised.

[Bundle 2]

There can be little doubt, the value of the proposed dwelling must be greatly increased as a result.

Personally and IMO the trees contribute hugely to the appeal of the building. They must do so without being compromised , then there are no unusual management issues with them. ( and no liability concerns etc ) The value of getting the planning off from the right premis.

There is I am sure alot of pressure on developments in the UK. We are but a small island with many people and rushing the housing sector demands will only lead to conflict. Bring on the new BS i say!

 

( it is sad to speculate that the new owners will not like the trees and want them butchered or removed)

Was there a TPO with that?

[Giles Hill]

( it is sad to speculate that the new owners will not like the trees and want them butchered or removed)

Was there a TPO with that?

 

I'm not sure if they're TPO'd actually, but I think the way the new building is arranged will hopefully minimise any conflict.

 

Trying to avoid future conflict is (ideally) part of the process - it's no good making sure that a tree's roots are protected during site work, if it ends up overhanging the building in 5 years time or overshadowing the whole back garden, so that the new house owner ends up pestering the Local Authority until the tree is topped or felled – TPO’s can be overcome.

 

The largest green tree on the drawing is a multi stem - it's broad rather than tall, it’s in the front garden and the nearest bit of building to it is the garage, so I’m confident it’ll be ok. The blue coloured oak between the houses is perhaps a different matter…

 

Any way, it’d be nice to have some software that drew the odd shaped canopies on AutoCAD rather than doing them manually.