UKTC Archive

Re: Windshield/Drive-by | Speed Limit Bankruptcy

Subject: Re: Windshield/Drive-by | Speed Limit Bankruptcy
From: Wayne Tyson
Date: Dec 04 2019 00:22:22
On one of the other iterations of this thread, I posted a GSV photo as an
example of how a drive-by could miss a defective tree. No one responded.

It is quite true that the drive-by concept is limited, and that is what
makes this discussion so useful. I only hope that it does not invoke a kind
of false sense of security. I suspect that good judgment should always
(pardon the expression) trump "criteria" or any other *subordination* of
the mind to a check list. Still, in the case I offered, I would have missed
that particular tree on a drive-by. I offered it to show myself up, and to
see if anyone else might have caught it. Researching failure before they
occurred via GSV has been a big eye-opener to me. We can't catch them all,
but by such experience we can re-examine our assumptions and perhaps
improve on them by such means.


On Tue, Dec 3, 2019 at 2:53 PM Julian Dunster <> wrote:

Drive by using a bicycle (or motor bike) means moving from tree A to
tree B and then stopping to look at the tree. Otherwise you cannot meet
the standard of care for both activities at the same time. That is, if
you were driving the bicycle with all due care and attention, it is
extremely unlikely you can claim to also have done a competent drive by
assessment of the trees at the same time. This was an issue in one of
the inquests I worked on in Hong Kong and I am aware it was an issue in
a drive by case in California where it was claimed that the driver,
traveling at ~ 40 MPH also met the standard of care for what we call a
Level 1 assessment (drive by, walk by, fly by).

What needs to be remembered is that the drive by or windshield survey is
only designed to capture the really obvious problems. It was never
intended to be anything other than a coarse filter and should never be
used in any other capacity.

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

North American distributor for Rinntech

On Tue/12/3/2019 11:10 AM, Simon Jones wrote:
In the past I have done drive-by tree risk assessments on roads, but not
using cars, using mountain bikes. So properly, “ride-by” assessments. This
was significantly quicker than walking would have been, and significantly
more thorough than driving.

Probably uneconomic on long stretches of Tasmanian highway, but for
urban and suburban roads, I found it effective. Compared to a car it is
slower, but we found we missed less, it didn’t need a driver, so reduced
labour costs, it was easier to pull over when something about a tree
suggested it would be prudent to look closer, and with trees in wide
verges, we could specify a 360° cycle round of the trunk. I remember we
found more than one tree with defects or fungal fruiting bodies on the
other side of the trunk, not visible from the road.

I haven’t seen any mention of bicycles in this interesting thread: is
this because it’s been tried and discounted for good reasons I’m unaware
of, or because we’ve all just been thinking cars? I’m inclined to think
that in some circumstances, there would be an economic case for ride-by
assessments. After all, how many miles a day can a fit man on a bicycle
cover? Twenty? More?

Kind regards,


Simon Jones


Surrey:  01737 XXXXXX
London: 0207 XXX XXXX


-----Original Message-----
From:<mailto:> <
<>> On Behalf Of Julian Morris
Sent: 03 December 2019 14:20
To: UK Tree Care <<mailto:>>
Subject: Re: Windshield/Drive-by | Speed Limit Bankruptcy

3700 miles x 2 sides = 7400 frontage miles. If 5 miles a day on average
could be done by an inspector on foot, that works out as 1480 days, and
based on 250 working days a year that's a full time job for 6 inspectors a
year. c. £200k. Not quite bankruptcy. Especially compared with the cost of
one negligence fatality a year.

Julian A. Morris - Professional Tree Services  and

0778 XXX XXXX - 0141 XXX XXXX

Sent: Tuesday, November 26, 2019 at 10:42 AM
To: "UK Tree Care" <<mailto:>>
Subject: Re: Windshield/Drive-by | Speed Limit
To have a look at the back of every tree that could fall onto the
highway could bankrupt the state government.
OK, you have an unusual situation of low population density and long
tree lined roads but even so your conclusion that walk by rather than
drive by tree assessment could "bankrupt the Government" seems like a
bit of a stretch, to me.
Hey, just thought of something.
What about Google Earth "Fly By" assessments?
On 2019-11-25 20:05, David Evans wrote:
<<It seems to me to be like scanning one side of a two sided piece
of paper and believing that you know the whole story.>>
Hi David
There's no belief that they know the whole story.  The design is
that one side of paper will be scanned at speed.
The context is Tasmania's Depart of State Growth has about 3700
miles of roads and millions of trees.  Trees provide many benefits
that they need, and the overall risk from tree failure is extremely
low.  Given this, to have a look at the back of every tree that
could fall onto the highway is not reasonable, proportionate, or
reasonably practicable tree risk-benefit management.  To do so might
bankrupt the state government, or mean they couldn't provide many
other important services.  The design is that they're trying to find
'obvious defects'.  To try and find defects that aren't obvious by
looking at the back of each tree would be grossly disproportionate
to the likely reduction in overall risk.
Acer Ventura
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The UKTC is supported by Bosky Trees arboricultural consultancy