Tree safety management

A tree can fall down because its roots can no longer stabilise it against wind pressure.   A limb of a tree can fall down after it has lost the necessary mechanical strength to support its weight or to resist wind pressure.   If the roots of a tree are able to stabilise it, if its trunk does not have enough mechanical strength, it may break-off and fall to the ground.   

Tree safety management is based on risk assessment.   A hazard is anything that could cause harm such as falling trees, falling branches, falling trunks.   A risk is the chance - high or low - that someone will be harmed by a hazard.  

Trees should be inspected at intervals according to the level of risk and timely preventative action when necessary.   The basic questions are:

• Does the tree show warning signs that it will fall down completely, or a branch will fall off, or that a trunk, or part of a trunk will fall off?
  
  
• If there are warning signs, is there a risk of injury?
  
  
• What remedial action is needed if there is a risk of injury?

Warning signs

These include:

• Top-heaviness, e.g., as indicated by excessive swaying in the wind.

• Lifting root plate, tearing out of roots, extensive root damage, or root loss.
  
  
• Large cracks in the ground around tree roots.
  
  
• Cracks or splits in trunk or large limb.
  
  
• Broken trunk or large limb.
  
  
• Hanging broken trunk or large limb.
  
  
• Large amount of decay in a trunk or large limb.
  
  
• Forks involving big limbs that show signs of weakness or possible failure at the centre of the fork, e.g., cracks, bark-to-bark contact, hollows that may be water-filled and bulging growth.  Fork failures, leading to shed branches, are more common in beech trees, certain types of willow, poplar, horse chestnut, and ash.
  
  
• Signs that the tree is in poor health, or may be dying, e.g., smaller than normal leaves, dead leaves in summer, dead limbs, much fungal growth.
  
  
• Cuts and other indications that the tree may have been damaged by machinery, vehicles or browsing animals.
  
  
• Frequent exposure to strong wind and signs that nearby trees have suffered wind damage, or have been blown over.

Young trees and saplings are unlikely to present a serious risk of injury if they fall on somebody but large trees, heavy sections of trunk or large branches are more likely present a risk of injury if they fall down.