UKTC Archive

Re: Windshield/Drive-by | Speed Limit Bankruptcy

Subject: Re: Windshield/Drive-by | Speed Limit Bankruptcy
From: Julian Dunster
Date: Dec 03 2019 22:53:27
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-----
<<>> On 
Behalf Of Julian Morris
Sent: 03 December 2019 14:20
To: UK Tree Care 
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" 
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