UKTC Archive

RE: RE: Drop kerbs

Subject: RE: RE: Drop kerbs
From: Jim Quaife
Date: Dec 28 2018 11:59:17
Vehicle crossovers on highway land have to be adoptable.  To that end one has 
no choice but to use the Highway Authority's specification.  I am involved 
with a bit of a tussle currently and it is interesting that the depth of 
excavation required is 230mm.  Whereas 5837 is concerned about areas, roots 
actually occupy volume.  Accordingly I reach my opinions having discovered 
the rooting depth profile.  If, as in my current case, the roots are still 
present at a metre deep, I stopped digging because that said to me that the 
loss of the roots in the top 230mm is unlikely to be significantly harmful.
Don't forget to think about the entire root system, and also that the species 
in your case is lime, which is recorded by Matheny and Clark as attached.
I am not saying that all crossovers are acceptable, but to repeat the closing 
sentence in a past article of mine: if all you need is a calculator, why do 
you need to know anything about trees?

-----Original Message-----
[] On Behalf Of Julian Morris
Sent: 28 December 2018 11:37
To: UK Tree Care
Subject: Re: RE: Drop kerbs


With caution, APN12 conflicts substantially with BS5837.

Drop kerbs and their foundations will remove roots. Are these roots and the 
rooting volume around them essential to maintain the vitality of the trees? I 
believe BS5837 4.6.3 (a) and (d) could provide a solution (if one can be 
provided that doesn't involve a no-dig one).

Julian A. Morris - Professional Tree Services  and
0778 XXX XXXX - 0141 XXX XXXX

Sent: Friday, December 28, 2018 at 10:14 AM
From: "Jasper Fulford-Dobson" <>
To: "UK Tree Care" <>
Subject: RE: Drop kerbs


I've had the same issue to deal with before. 

Avenue of TPO limes on a narrow semi-rural residential road with large 
detached houses, many of which had been rebuilt or in-filled over the 
previous years, with 2-3 dropped kerbs between the trees setting the 
precedent. LPA's tree officer pointed out that the other examples had been 
done before the 2012 revision of BS5837 so "precedent" could not be used as 
a viable justification, raised concerns about how the levels would match 
("no-dig" construction to ramp up over the RPA from the existing road 
level), suggested the trees would be adversely impacted and objected with 
no room for manoeuvre. The application was refused and the client wasn't 
prepared to test this at appeal.

Suffice to say (as others have experienced) all trees near the pre-2012 
dropped kerbs are in fine and healthy condition, despite the level changes 
being very subtle.

Despite the expectations of some, as arb consultants all we can do is try 
and help guide the process by setting out the principles to take to reduce 
the impact on trees. Make sure you re-read Tree Roots in the Built 
Environment, BS 5837, APN12, Built Environment ( and 
Geosynthetics info/case studies then consider the special engineering 
solutions available that might help overcome or mitigate your problem. Put 
these forward to your client's designers making it clear you are not an 
engineer or landscape architect and advise them to prepare additional cross 
sectional drawings (before and after) showing the built structure and the 
level changes, especially how they can be matched. 

Good luck.


-----Original Message-----
<> On Behalf Of Paul Hawksford
Sent: 24 December 2018 22:09
To: UK Tree Care <>
Subject: Drop kerbs

I've a site with a proposed residential dwelling, unfortunately, the 
architect also proposes a couple of drop kerbs in the public footpath 
outside leading into the access driveway. The kerb would be sited within 
the RPA of two nice mature lime trees which sit in the footpath. Drop kerbs 
have been installed in the same area, some ten years ago and very close to 
similar trees along the road and he's hoping this will help the 
application. I've dealt with drop kerbs before and viewed them with a 
cautious eye, consequently, I told those architects it would be difficult 
to convince planners that it could be done sympathetically. Has anyone 
experience, or produced a method statement for this...?


Paul Hawksford
Principal Arboriculturist

16 Ballydonaghy Road

County Antrim
BT29 4EP

M: +44 (0)7746 XXXXXX


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