UKTC Archive

Re: Diameter callipers

Subject: Re: Diameter callipers
From: Simon Pryce Arboriculture
Date: Aug 16 2019 10:20:13
There is some science in previous BS5837 distances was the table in the 1980 version with shorter distances for conifers, reflecting that conifer root systems are inherently more compact and the 1991 version which factored in age and vigour.

Jim's too diplomatic to say the the 12x figure was pulled out of the air - it works because most (NOT all) roots are closer than that in most cases.  The words often overlooked in the 5837 2005 and 2012 are that the RPA should be an "_area equivalent__to_" a circle.  In open ground a circle might be a reasonably accurate reflection of where the root actually are, but not many development sites round here are large and open.  Just drawing 12x radius circles round every tree is fine geometry, but doesn't need any arb expertise. However it is hard to get out of the habit of drawing circles and straight lines - those Helix geometry sets we had at school didn't help.

Simon





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