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Asia Tree Preservation, Ltd. has a team of highly trained Certified Arborists, Certified Tree Risk Assessors, and Certified Climber Specialists on staff. Please feel free to contact us right away if you have a concerned tree on your property that requires tree risk assessment: email us:
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or call us: +852 26695126
What is Tree Risk Assessment (Hazard Tree Inspection)?
TRA Methodology
Tree risk assessment is the systematic process of assessing the potential for a tree or one of its parts to fail and, in so doing, injure people or damage property. All trees have the potential to fail. The degree of risk will vary with the size of the tree, type and location of the defect, tree species, and the nature of the target. Tree risk assessment involves three components:
- a tree with the potential to fail,
- an environment that may contribute to that failure, and
- a person or object that would be injured or damaged (i.e. the target).
We follow the evaluation procedure established by the International Society of Arboriculture (Matheny and Clark, 19941). This procedure requires evaluating the tree failure potential (likelihood to fail), the size of the part that would strike the target, and target (what would be damaged or injured) to develop a risk rating. Risk rating = failure potential + size of defective part + target rating
Matheny, Nelda and James R. Clark. 1994. Photographic Guide to the Evaluation of Hazard Trees in Urban Areas. International Society of Arboriculture. Champaign, IL. 
Why Is Tree Risk Assessment Necessary?
In large cities that have trees, it is important to find the balance between both tree preservation and safety of pedestrians, vehicles, and other potential high value targets.
Trees provide a great benefit to the environment and give us enjoyment wherever they are found whether in the park, forest stand or urban setting. However trees can also be hazardous if they fail in any one part by limb or entirely and have the potential to strike a “target” such as property or persons in the area. Trees may develop defects for a variety of reasons: their environment, incorrect tree selection/placement, species type, or trees of over maturity (senescence). Any tree has the potential to be a hazardous tree depending on a number of conditions which Certified Arborists are trained to identify.
At times, a tree may require Aerial Assessment if defects are located within the crown of the tree.
When deemed necessary, ATP's Certified Arborists/Tree Risk Assessors will use high level instruments such as the ARBOTOM Sonic Tomograph and the RINNTECH Resistograph to determine internal problems in a tree. 
Additionally, ATP may use the Air Spade air excavation device for thorough assessment of a tree's roots.Client Testimonial: Following the assessment and reporting on the conditions for over 4000 trees in a corporate community headquarters on the South China Sea the corporation VP provided favorable recommendation concerning Picker’s hazard abatement tree plan saying; “[we are] …absolutely convinced we will now have a more sustainable outcome as a consequence. I am thus confident and now fully appreciate the critical role arborists play in maintaining and preserving the environment.”
Another method of covering a large group of trees for evaluation of safety is the Tree Survey/Inventory. Click here for more information. |
At times it is necessary to utilize highly technical devices for determining the structural stability of a tree during tree risk assessment (hazard tree inspection). The RINNTECH Resistograph (drill resistance measuring device) and the RINNTECH ARBOTOM (sonic tomograph device) can offer objective scientific data on the internal conditions of a tree.
