Utility Arboriculture Conference
Tree risk management
Simon Richmond
Technical Officer,
Arboricultural Association
Background
• History
• Context
• Benefit
• Risk
• National Tree Safety Group (NTSG)
• Proportionate, balanced response
• Power lines
• Railways
Influencing cases
‘The Birmingham Ash’
Birmingham City Council was fined £150,000 for
breaching health and safety law after three people
were killed by a falling tree on 3rd December 1999.
The council pleaded guilty to the charge brought by
the Health and Safety Executive (HSE).
The Birmingham Ash
Judge Richard Wakerley QC said: "The condition and the
danger the tree presented would have been obvious to
anyone making a close inspection of that tree."
Influencing cases
• POLL vs. VISCOUNT ASQUITH of MORLEY
• (POLL V BATHOLOMEW)
• An accident involving a motorcyclist colliding
with a fallen tree in July 2001
• Judgement in May 2006 in favour of claimant
• Focus on competence by experts
• Levels of Inspection
• Foreseeability
2006
2007
National Tree Safety Group
(NTSG)
• Group first met in 2006 – convened by Sir Harry
Studholme, Forestry Commissioner
• Formally launched January 2007
• Commissioned 3-part research from DARM (Centre for
Decision Analysis and Risk Management):
1. Quantify risk to public health from falling trees
2. Perceived risk and public concern
3. Evaluation of future control measures
• Legal advice to establish duties and responsibilities in
relation to tree risk management
• National Conference May 2008
TREE
MANAGEMENT
FOR
270 attended
PUBLIC SAFETY
Towards an Industry Statement
A ONE-DAY CONFERENCE
NATIONAL TREE
SAFETY GROUP
29th May 2008
NTSG Management group
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Chair: Judith Webb, Forestry Commissioner
Ancient Tree Forum
Arboricultural Association
Confederation of Forest Industries
Country Land and Business Association (and NFU)
Forestry Commission
Institute of Chartered Foresters
London Tree Officers Association
National Trust
Royal Institution of Chartered Surveyors
Tree Council
Woodland Trust
Observer: British Standards Institution
NTSG Objectives
To develop a nationally recognised approach to
tree safety management.
To provide guidance that is proportionate to the
risks posed by trees.
To work transparently and inclusively with as
wide a stakeholder group as possible.
To provide guidance that is strategic, rather than
prescriptive, and authoritative.
Who is the guidance for?
Anyone responsible for managing tree safety,
or governing it:
Individual householder with trees
Small business
Farm / Estate
Golf course / Caravan park
Local Authority – urban / rural
Major land owners / tree managers / Utility managers
Regulators
Law courts
What do we know?
The overall risk of harm to the general public from
falling trees or parts of trees is extremely low.
We already manage trees extensively for both their
health and our safety (and network resilience).
In recent years there has been an increase in the
‘defensive’ felling of trees for fear of litigation.
What do we know?
• It is clearly unreasonable and impracticable to inspect
all trees, regardless of their position
• Trees provide a wide range of benefits to the whole
of society but responsibility (duty of care) rests with
the owner / manager
• Tree owner /managers (duty holders) are in the best
position to understand what trees they have and the
context of those trees
NTSG Principles
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Trees are good
Living natural organisms – bits naturally fall off
The overall risk to human safety is extremely low
There is a legal duty of care for safety
A balanced approach - reasonable and proportionate
Strategic guidance
The HSE’s
Tolerability of Risk
Framework
(Threshold risk level:
1 in 1 million)
Where does tree-related death
lie on the ToR framework?
Part 1 of the DARM research shows that there were 64
fatalities to the public during the ten years from 1 Jan
1999.
The mean annual fatality rate in the UK is therefore 6.4.
The population exposed is 60 million.
Therefore the overall risk to individuals is about
1 in 10 million or less per annum.
Tree risk in
perspective
Overall risk v individual risk
• Of course, some individual trees will pose a higher risk
than 1 in 10 million, while others pose a lower risk
• The trick is to find the very few trees that may cause
damage or injury before they find us, by applying
sensible risk management
• Some ‘target areas’ by their nature, represent a
different level of risk
Power lines present a different
level of risk
Railways present a different
level of risk
Photo courtesy Network Rail
(De-railed train in distance)
Photo courtesy Network Rail
Do trees generate ‘societal risk’
or ‘societal concern’?
The HSE states in its SIM:
“... However, the low level of overall risk
may not be perceived in this way by the
public, particularly following an incident.”
DARM part 2 research
Prof. David Ball explored the public perception in
relation to harm from falling trees, in comparison to
other known causes of concern.
He studied governmental policy and other existing
research in this area.
He identified that perception of risk must always be
viewed in relation to the benefit derived.
Falling trees
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Public desire for extra control
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DARM conclusion
The conclusion is that there are no grounds for any
other approach to tree safety management than the
application of rational, cost-effective measures.
In the public interest, measures which are not shown to
be rational or cost-effective should not be
implemented.
The risk-benefit trade-off
Risk of harm
Benefit of thing
or activity
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Challenges
• How to make a risk-benefit assessment?
• Conventional HSE calculation of risk v cost of risk
reduction does not recognise the resultant reduction
of benefit – to individuals and the whole of society
• Risk reduction v benefit reduction - i.e. Assessment in
context of benefit
• Further discussion with HSE is on-going
NTSG Outcomes
• Position Statement
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NTSG inclusive – open membership
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Tree risk management - proportionate to real risks
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Evidence based
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Balance between Risks and Benefits
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Risk benefit trade off
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Calculation – contextual – duty holder decision maker
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Take account of role and contribution of trees
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Large organisations – formal policy
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Reasonable - Non-defensive
NTSG Outcomes
Guidance at three levels:
1. Information leaflet or ‘briefing note’ – a small (4
sides of A4) leaflet summarising the principles.
2. Concise guidance document (8-12 pages) - providing
full detail of the principles and how they might be
applied in a number of case studies.
3. The full guidance document, printed hard copy
and/or web-based, including appendices of research
and background information.
NATIONAL TREE SAFETY GROUP
Managing
trees
for safety
If you own a tree,
then you need
to read this leaflet…
Why read
this leaflet?
To help you
understand the
issues around
tree safety
and come to
a balanced
conclusion: one
that ensures
that trees,
essential for
the ecosystem
and common
good, can
thrive in the UK,
uncompromised
by unnecessary
safety
management.
NTSG
NTSG Full Guidance
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Discusses the many benefits that trees bring to
society
Considers the risks from falling trees, within the
wider context of other risks
Outlines the legal framework for considering trees in
relation to public safety
Seeks to provide reasonable and practical
measures to fulfil legal responsibilities
Provides several scenarios as models for putting
these measures into practice.
NTSG Full Guidance
Content of the main guidance document reflects
NTSG principles:
• Trees are good
• Living natural organisms – bits naturally fall off
• The overall risk to human safety is extremely low
• There is a legal duty of care for safety
• A balanced approach - reasonable and proportionate
• What you should do
When will the Guidance be
available?
Possible publication – July / August 2011
Thank you
Practical Guidance
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Key Issues:
Duty holder’s management strategy
Which trees to inspect
Level of inspection – who should inspect?
Frequency of inspection
‘Work in progress’ Diagram courtesy Jeremy Barrell
‘Work in progress’ Diagram courtesy Jeremy Barrell