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Common sense tree safety (FWN 29)

20 September 2017

We often take trees for granted due to their long lives; they appear to be permanent features in the landscape.

However,  unlike truly permanent features, trees are living – and changing – organisms.  Often these changes result from the physical growth of the tree, but many changes result from disease, decay, storm damage and vandalism.  And where trees with these changes occur next to spaces occupied by other people, there is a risk of damage or injury.  The owner of the tree has a legal duty of care to make sure that their tree does not cause damage or injury. In this article we take a look at how to mitigate that liability, but with a common-sense approach.

The emphasis on the common sense approach arises from the extremely low risk of death (one in 10 million chance) caused by falling trees, or tree parts.  Representing approximately 55 accident and emergency visits per year, the risk from trees is considerably lower than the 2.9 million leisure-related accident and emergency visits per year.

Risk is acceptable where certain conditions apply:

  • where the likelihood of damage or injury is extremely
  • where the hazard (that is, the tree or branch itself) is obvious to all using the land adjacent to the tree
  • the benefits of the tree are obvious
  • removing the risks would result in the loss of the benefits
  • there is no reasonably practicable way to deal with the risk.

At the most basic level of risk identification is risk zoning.  This starts as a map-based exercise, identifying where people are in relation to the trees on your property, and the nature of the use of the land they are on.  Risk zones would typically range from 1 to 5, with 1 being high risk and 5 being low risk.  High-risk zones would include places where there are many people for sustained periods of time, or many people moving at high speed eg. schools or ‘A’ roads.  At the opposite end of the spectrum, low-risk zones are where there are few people on an infrequent basis or moving at low speed eg. quiet footpaths or quiet country roads.  The risk zones should be clearly marked on a map.

Risk zoning alone is however not sufficient to fulfil the tree owner’s duty of care.  This must be followed up by a tree survey.  There is no legal guidance as to the detail of a tree survey, but the standard of care demonstrated should be that of the ‘reasonable and prudent landowner’.  In carrying out their duty of care, a landowner does not guarantee the safety of a tree.

In being reasonable and prudent, the standard of care demonstrated by a landowner is expected to be the result of a balance of the risk posed by the trees, and the cost of the type of tree inspection.  The standard of inspection is indicated by courts to be proportionate to the ‘size of and resources available (in terms of expertise) of the landowner’.

The duty of care differs where the landowner is in the business of growing and managing trees.  In this case, the duty of care falls under ‘The Health and Safety at Work Act 1974’, whereby the landowner must ‘make a suitable and sufficient assessment of the risks to the health and safety of persons, not in his employment arising out of or in connection with the conduct by him of his undertaking’.  Failure to exercise this duty of care can constitute legal criminality. However, in going about their duty of care, employers are expected to do what is ‘reasonable and practicable’.

In both circumstances above, a balance must be made between the risk posed and the resources required to assess tree condition.  In carrying out tree inspections, the duty of care obligation requires ‘obvious defects’ to be recorded and acted upon.  Obvious defects are considered to be those which can be identified by most people, regardless of specialised tree knowledge.

Whatever the method employed, it must be defendable.  Where there is a relatively small tree population it may be entirely possible to inspect and record every tree.  But where there are extensive populations of trees it would be acceptable to record the location and details of only those trees requiring remedial work.  In the latter case, where there is also a high-risk zone, the method of inspection can remain the same but the frequency increased.
Further reading can be found on Common Sense Risk Management of Trees, downloadable as a PDF here.

Malcolm Young, SAC Consulting

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