UKTC Archive

RE: Drop kerbs + Lime

Subject: RE: Drop kerbs + Lime
From: Mark Hudson
Date: Dec 29 2018 17:31:36
Reference Jims extract from M&C re Lime and the drop kerb; during the 1987
"hurricane" I was woods and parks manager at Hatfield park (Herts) and we
had 3 mature, apparently healthy (but not overmature) common lime blow over
on the avenues - rather than lose them without a fight, and as we already
had a tree contractor on site with matador (+ 10t winch) we "heavy
pollarded" them back to about 6-8m (from distant memory), slightly enlarged
by excavator the crater left by the blown root plate, winched them back
upright and refilled any remaining crater still open

They survived and continued to grow for at least 4 1/2 years, I moved on in
1992 so don't know what the longer term held for them - and yes, I am aware
there will have been a multiple of entry points for pathogens thereafter

Again, from distant memory, upended root plate radius was c. 1.5 - 2m

Can't claim it as anything like replicated research, rather works carried
out on a "worth a try" basis as we had lost so many trees that night

If it was today, I would have air spaded radial trenches out to maybe 10m
every 2-3 years to assess root redevelopment, if they survived......


-----Original Message-----
[] On Behalf Of Jim Quaife
Sent: 28 December 2018 12:03
To: UK Tree Care
Subject: RE: RE: Drop kerbs

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
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
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


P Please consider the environment - do you really need to print this

Please be GREEN and leave it on the SCREEN


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