What is Tree Risk Assessment?
Trees offer a wide range of benefits when present in urban environments. These monetary, ecological, sociological, and aesthetic benefits increase as trees grow into maturity. However, these benefits don’t come without their risks.
As trees grow, the likelihood that they will shed branches, suffer from rot, or develop other conditions that could lead to failure increases. Most trees are located in areas where the risks associated with these failures are minor; however, when trees located in urban environments suffer from failures, property could be damaged, events could be disrupted, and people could get injured.
That’s why periodic evaluations, called Tree Risk Assessments, should be conducted to identify any potential tree conflicts.
Why Tree Risk Assessment is Important
Did you know that property owners have a legal responsibility for caring for the trees on their properties? A Tree Risk Assessment allows property owners to anticipate potential tree failures before they happen. Identifying these risks enables property owners to mitigate risks and avoid the costly repairs or medical bills that could be incurred due to a tree or heavy limb falling.
The Risk Assessment Process
Tree Risk Assessment is divided into three levels ranging from visual to advanced assessments. It is the responsibility of the Tree Risk Assessor to explain, in detail, what each of these levels is so that customers have a clear understanding of the services that are being performed. At that point, it is the client’s responsibility to choose what level of inspection needs to be done. Most risk assessments are level two, but it’s important to understand each level to make that determination.
At Tree Care by Robert Miller, we want to ensure that information regarding these three levels is available to you long before you schedule your consultation so that you can make an educated decision regarding the scope of work. In addition, these assessments factor in the likelihood of failure, the probability that a failure will result in an impact with structures or people, and the consequences that could arise should a failure occur.
Level 1: Limited Visual Assessment
This assessment is geared towards identifying trees that pose an imminent or probable threat to homeowners or the property. These assessments do not take long to perform since they are not as thorough as Level Two or Level Three assessments.
A Tree Risk Assessor conducting a Limited Visual Assessment should:
- Identify location and selection criteria of trees assessed.
- Calculate an efficient route for inspecting large populations of trees.
- Perform walk-by, drive-by, or airborne assessment of trees.
- Document the route taken for assessment.
- Record location of trees at risk of failures.
- Evaluate potential risk based on visual observation and assumption.
- Submit recommendations based on findings.
Level 2: Basic Risk Assessment
This is a ground-based assessment commonly conducted by an arborist due to a client’s request. It involves a visual inspection that must be conducted both up close and at a distance. The Tree Risk Assessor will inspect the trunk, branches, and any visible roots for any potential defects as part of this inspection. This inspection may involve measuring tools, digging tools, binoculars, a magnifying glass, a mallet, a probe, a compass, and a camera but not every inspection requires them.
A Tree Risk Assessor conducting a Basic Risk Assessment should:
Locate and identify the trees in need of a risk assessment.
Document any concerns found at the site.
Identify potential targets and a target zone.
Evaluate potential risks, the likelihood of failure, and the consequences of a failure.
Review any previous site history.
Create a mitigation plan that includes an estimate of costs for the client.
Visually inspect the trees using any necessary tools as needed.
Submit findings to the property owner.
Assess tree loads and general tree health.
NOTE: A Tree Risk Assessor may recommend an Advanced Risk Assessment to gather more information pending their findings.
Level 3: Advanced Risk Assessment
The advanced risk assessment is the most thorough of the three assessment levels. It provides a more in-depth look at specific tree parts and their potential for failure. This inspection is usually necessary if there is not enough conclusive information derived from a Basic Assessment. A combination of expert opinion and specialized equipment is typically needed to conduct an advanced assessment. As a result, conducting one of these assessments can be a lengthy process.
A Tree Risk Assessor conducting an Advanced Risk Assessment has a wide variety of techniques that could be employed based on the specifics of the job.
These techniques could include:
Aerial Evaluation
Inspect for stem or branch defects, decay testing, photo inspection
Site Evaluation
(Soil profile, root depth estimate, mineral testing)
Decay Testing
(boring, x-rays, sonic tomography, fungal analysis)
Target Analysis
Property value assessment, occupancy risks, disruption assessment
Health Testing
Tree ring analysis, starch test, shoot measurement, vigor analysis
Root Evaluation
Root and root collar excavation, root decay test, ground-penetrating radar
Storm and Wind Load Analysis
Exposure test, Intervaled wind reaction monitoring, computer-based estimations
Trunk Lean Evaluation
Measuring and assessing changes in lean
Load Testing
Hand pull, static pull, measured tree dynamics
“They are wonderful. I had them take down 4 pine trees at my home in Southern Hills. They are very efficient and professional. They know what they are doing! My yard was hardly affected by their presence since they took great care to minimize yard damage. They even cleaned the road after they were done. HIRE THEM YOU WILL NOT BE SORRY. “
– Joe Weston
“Tree Care [by Robert Miller] had trimmed up trees as well as taken down sixteen trees. It was a big job that took all day and they worked continuously to get it all done. They went above and beyond what was expected. Professional, respectful and would recommend them to anyone that wants quality work. Extremely satisfied with the end results. Thank you!”
– Luann U Peritzian
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