What is a Tree Risk Assessment and Why is it Needed?
If you work in arboriculture, then it is likely that you understand the risks at play when performing your everyday roles. In fact, you are likely already spending almost an hour daily preparing, checking and maintaining your gear. However, unless you work as a team leader or manage these teams, you might be unfamiliar with the assessments of risk that take place before any job is undertaken. This is known simply as a ‘risk assessment’.
A risk assessment is intended to be a copy of all the known risks that need to be considered throughout all phases of work, and after, within an acceptable time frame. This is to assess all possible risks of falls or injury when working at height, what risk the tree is posing at all levels, and the exact measures required to return the tree to a safe level, or to safely remove the tree altogether.
Read on to learn more about what a tree assessment is, what common checks are made and why.
What is a Tree Risk Assessment?
A tree risk assessment is where arborists are required to assess the health and safety concerns associated with a tree. There are various levels of assessment depending on the projected risk the tree poses.
Why is a Tree Risk Assessment Needed?
Tree risk assessments can be carried out for a number of reasons. If you are working on trees near a road, footpath, public or private building or worksite, then you will need a risk assessment to ensure the safety of everyone who may likely be in that area during your tree work.
Public safety and risk of injury, from large tree roots that could be a trip hazard or damaged branches that are at risk of falling and causing injury. They are also used to identify hazards to workers onsite, too.
Tree risk assessments may also be commonly conducted to assess susceptibility to storm damage and could be carried out afterwards to monitor any damage that has occurred. They can also act as a preventative measure where tree disease is concerned, identifying disease before it spreads could save multiple trees, which in turn is protecting wildlife habitats. Additionally, they may act as protection for trees at risk of being removed if they can be proven safe. In this case, the risk assessment may take place due to a Tree Condition Survey, which we will look through in closer detail.
What Does a Tree Condition Survey Look For?
Tree Condition Surveys cover a wide range of different risks from safety issues to tree health. These assessments also need to take into account any Tree Preservation Orders or infringement of the Wildlife and Countryside Act to ensure compliance.
Tree Condition Surveys look at:
- Potential hazards,
- Access to the tree,
- The level of risk posed,
- The control measures needed to stabilise, reduce or remove the risk.
- Protected Wildlife
To better understand how a risk may be found, take a look at some of the checks below:
Disease & Decay
Branches that have no leaves in the spring and summer seasons, crumbling bark or visible fungus (such as Ash Die Back) are all signs of disease in trees and will need to be assessed in a Tree Condition Survey. In the early stages of a tree falling victim to disease, it may not be visible to the untrained eye. A tree risk assessment uses a methodological approach, other than just a visual inspection, to fully assess the current and long-term health of the tree(s) in question.
‘Tree sounding’ or the use of a Resistograph can help a professional tree surveyor assess if a tree has any internal decay or structural faults. The use of a PiCUS system or increment borer can give an indication of the health of the tree.
These more intrusive methods allow samples to be taken from inside the tree, where issues can be easier to identify. In a safe location, it may well be possible to retain a defective or hollow tree as a beneficial wildlife habitat. It is too easy to damage the landscape by cleansing the essential environmental features decaying trees provide.
Tree and Branch Stability
‘Tree pulling’ is a test carried out to test the strength of a tree and its root system. Also known as Static Load Testing, this measures the load-bearing capacity of the tree as well as taking into account how it would cope under extreme wind conditions. It also tests whether any adjustments would need to be made to make the tree safer, such as Crown Thinning or Crown Reduction.
Risk of Personal Injury
During a Risk Assessment, you will also want to check and highlight any likely safety risks the work could pose to the public and or the contractor.
Depending on the tree location the risk to the general public may be quite low. Knowledge of dead or broken branches, weak root systems or extensive decay will be a concern to arborists and may affect how they safely carry out the proposed work. These need to be clearly highlighted to the client and contractor to reduce the risk of injury or death.
The Root System of the Tree and Subsidence Issues
Tree roots that go beneath the foundations of a building may cause immediate or future structural issues if a tree is heavily reduced or removed. Soil core samples along with the knowledge of tree species and root influence can help identify the potential for ground heave or subsidence following tree work. All trees growing near to property should be professionally assessed before any work is carried out. Tree roots can also infringe on services, so any nearby drainage may also need to be checked.
To assess a tree root system you would normally include the following:
- Ground/ soil type
- Proximity to other trees and buildings
- Maturity and height if the tree is not yet at full expected growth
- Depth of property foundations
- Water requirements of the tree
- Nearby drainage and services
Highway Safety
Road safety is a crucial consideration for all road users. It is important to provide motorists with clear and legal signage to ensure road safety. Road signs and any traffic management systems should be correctly planned to protect both the public and workers.
When planning it’s important to include the risk to any vehicle or plant placement and the potential hazards due to transit of debris during the work. This includes minimising the risk of visual and access obstructions for motorists, cyclists and pedestrians.
Staying Safe and Finding Staff with Arbjobs
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