UKTC Archive

Re: Windshield/Drive-by | Speed Limit

Subject: Re: Windshield/Drive-by | Speed Limit
From: Paul Barton
Date: Nov 25 2019 12:33:34
We did a significant length of A-roads in this way last year.

We didn’t have a strict written protocol (perhaps we should have) but our 
thinking was along these lines:

• Drive at 20-30mph in a van with flashing beacons and appropriate signage - 
one driver and one surveyor
• Stop wherever the surveyor saw:
    • A large mature tree - full 360 degree view of the trunk then required
    • Any other tree showing crown dieback or with strong lean toward the road

Other than the above, progress was made at a steady pace and we were pretty 
confident that we picked up the most significant issues.  As this approach 
had been explained to the client and there was no pretence that it was a 
detailed tree by tree assessment we were quite happy to work in this way.

Incidentally, we also made a running estimate of the number of ash trees 
along the route and plotted these numbers on a map as the authority were 
(sensibly) wanting some guidance as to the potential cost for large-scale 
roadside ash removals in case of prolific ash dieback.

On 25 Nov 2019, 09:58 +0000, David Evans <>, wrote:
I'm in Hobart at the moment. Helping the Tasmanian Government deliver a
reasonable, proportionate, and reasonably practicable approach to tree
risk-benefit assessment and management, following a coronial inquest into a
death on one of their roads.

One of the issues we were exploring today was the specification for a
windshield/drive-by specification. I've raised this on here before, when
trying to find out whether anyone had actually written one. It turns out
that, so far, no one has does (beyond that they will carry one out).

The straw poll I'd value your collective opinion on, is;

A driver and a spotter. Both sides of the road driven. At what speed do
you reckon a windshield/drive-by should be carried out to pick up 'Obvious

For example, is driving at around 30mph going to reveal significantly less
obvious defects than driving at about 10mph? Or significantly more obvious
defects than driving somewhere close to 50mph?

If you had to choose a speed limit, what would it be?

If you're uncomfortable posting your opinion on here, please email me off

As with all of VALID's publications, because it's a not-for-profit, when
this is completed I'll happily share with everyone under a creative commons

*Obvious Tree Defects Guide


Acer Ventura

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The UKTC is supported by Bosky Trees arboricultural consultancy