UKTC Archive

Re: Highway Authority Tree Risk Management

Subject: Re: Highway Authority Tree Risk Management
From: Julian Morris
Date: May 02 2019 14:02:32
You're so right, the risk of driving slowly could be greater than the risk 
from the trees themselves. Also having  to stop frequently where there is no 
hard shoulder is blocking the road. On corners and the likk this could be 
very dangerous, one could be rear-ended by a HGV.

I can walk at 4mph without breaking a sweat. Someone driving at that speed is 
a menagce to everyone else on teh road. Indeed, it woud almost certainly be 
an occende of 'driving without reasonable consideration for other road 
users". Trying to spot defects while driving would definitely be 'driving 
without due care and attention', making driving while on a mobile phone seem 
relatively diligent.

I suspect roads authorities would get little leeway from police. When 
inspecting, they're just road users, after all.

And here's the quetion for me. Would a drive-by have spotte the defect in 
'Cavanagh'. Not as I've read it described. I can't see how a drive-by as the 
only mean of triggering more detailed inspections being enough to discharge 
duty of care.

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

Sent: Thursday, May 02, 2019 at 11:58 AM
From: "GeoArb Ltd" <>
To: "UK Tree Care" <>
Subject: Re: Highway Authority Tree Risk Management


We have been putting together some guidance on this also and I am
interested in your thoughts.

Currently we drive past trees and don't attempt to rubber neck. We need to
keep pace with traffic so where possible we pull over with hi vis and
beacons, keeping outside the road envelope. We have a road inspection sign
on the rear of the vehicle and we always walk ahead of it. We also get out
and walk behind every tree we can. So it isn't really a windshield survey
but a drive to site survey, albeit lots off them. The geologists do a
similar thing.

This process of not driving slow means one person can do the whole survey
costing less technician hours and allowing for more survey detail by
walking. It takes a bit of time but an initial survey on 600km highway of
nature reserve, agricultural and towns takes us about 7 days. The areas we
cannot stop and survey are highlighted and shared with the lead highway
contractors. They then tell us when the road is next under traffic
management so we can access the trees and do a walk by.

I would say a windshield survey isn't recommended as driving slow is likely
to be more risky to the public than any risk the trees pose. Also we cannot
impose traffic management on other vehicles by driving slow, you need
cones, signage and traffic trucks to do this. No point being dangerous when
looking for danger.



On Thu, 2 May 2019, 22:04 David Evans, <> wrote:

Hi Jeremy

Thanks very much for the links.  I've read these.  They're very useful and
helped me get VALID's tree risk-benefit management packages to where they
are.  In simple terms, all a Highway Authority need do to reasonably
discharge its duty of care is

1) Carry out an 'Active Assessment' on high use roads (over 1400 vehicles
a day) on a 5 year frequency.

2) Ensure all staff have read the one page Obvious Tree Defects Guide, and
that it's available on the website.

3) Carry out 'Passive Assessment'.

What I'm particularly trying to nail down at the moment is 'windshield
survey' protocol/specifications as part of an Active Assessment.  And in
particular, what's a reasonable speed to drive at because there's a
cost-benefit issue here. Drive too slowly and you increase the risk of
traffic accidents.  Drive too quickly and your likelihood of missing
obvious defects increases.

To flesh the issue out a bit more.  Many authorities or agencies say
windshield surveys are effective and that they do them, but I've not yet
come across a guideline for the speed at which they're being carried out.
The only published source I've found for the value of windshield surveys 
the Rooney paper (2005) in the old ISA journal.  But he drove at an 
of 2mph with a spotter and a driver.  All the trees were out of leaf.  He
drove down both sides of the road if there were trees on both sides.  And 
'hazardous' tree was defined by a variation of Matheny & Clark where
ordinal ranking numbers were added (which we know is wrong).  I very much
doubt that anyone carrying out windshield surveys is following these


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