[CANUFNET] Sidewalks and trees

[brunopaquet at videotron.ca]

Bonjour Julian, 

Here are the two plans used by the Borough of Ville-Marie, Montréal, when
pits with existing trees need to be enlarged and a sidewalk installed. I
agree it's rather basic. Notes are in French of course. 

I hope it will be useful.

Bruno


-----Message d'origine-----
De : CANUFNET <canufnet-bounces at list.web.net> De la part de Julian Dunster
via CANUFNET
Envoyé : 24 avril 2024 17:06
À : Canadian Urban Forest Network <canufnet at list.web.net>
Cc : Julian Dunster <jadunster at gmail.com>
Objet : [CANUFNET] Sidewalks and trees

I am looking for design specifications that enable sidewalks to be built
close to trees and over roots.

Currently the most commonly used requirement in Canada and the US seems to
be a 4 inch thick concrete slab on top of compacted gravel that is at least
4 inches deep. That often means an 8 inch minimum excavation with associated
root damage.

We have access to a product called Combigrid which is a geotextile fabric
bonded to a biaxial geogrid. Ideally I would like to be able to lay this
onto the native soil (rake off or scrape off top inch or so of loose
materials) and then pour the slab straight onto that, possibly with mesh
reinforcing in the slab. The engineers have rejected that approach and want
compacted sub grade on top of the Combigrid.

The sidewalks seldom have to be rated to H20
(https://bandt-us.com/h-20-load-rating/#:~:text=H%2D20%20refers%20to%20a,16%
2C000%20lbs%20per%20wheel%20load.)
so in theory the design should be quite simple but in practice isn't.

I would appreciate links to or specifications for alternative ways to create
sidewalks that do not involve deep excavation into the root zones.

AND

- no, moving the sidewalks is seldom possible

- thinner slabs not accepted

- only concrete to be used.

- I need an affordable design that can be used regularly as this is not a
one off situation - it is a routine problem that I am trying to solve.

jd

--
Yours sincerely,

On Behalf of Dunster and Associates Environmental Consultants Ltd.

  

  

Dr. Julian A Dunster R.P.F., R.P.P.., M.C.I.P., ISA Certified Arborist, ASCA
Registered Consulting Arborist # 378, ISA Tree Risk Assessment Qualified
Honourary Life Member ISA + PNWISA

www.dunster.ca		www.treelaw.info		North American
distributor for Rinntech www.rinntech.info


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