Fall/Winter 2015

Tree Risk Assessment:

Mitigating the Risk of Failure with TRAQ

Inspecting mature trees periodically for hidden decay, structural weaknesses and diseases can extend their lives and mitigate the risk of failure of the tree or its branches. Falling trees and branches can cause serious injury to people and extensive damage to property. It takes a trained and experienced arborist to inspect a tree, conduct the required testing and interpret the results accurately.

All Almstead arborists have training in tree risk assessment and usually inspect trees visually when they are on site for issues with the trunk, crown, and root zone. In addition, some of our arborists have also undergone the more extensive Tree Risk Assessment Qualification (TRAQ) program offered by the International Society of Arboriculture (ISA).  The TRAQ method provides a standardized and systematic process for assessing tree risk. It helps arborists and property owners decide whether a tree should be retained, removed, or whether risk mitigation techniques, such as pruning, cabling, etc., should be considered.

The TRAQ system utilizes a detailed tree risk assessment form that arborists complete while inspecting trees on a property. In addition to basic data, such as species, diameter of the tree at breast height (DBH), tree height and crown spread, it also requires the arborist to record and evaluate other detailed information about the location, conditions, defects in the tree’s trunk, crown, and roots, as well as potential targets if the tree or its branches fall. Based on this information, as well as results other testing, using specialized tools such as a Resistograph (see image and graph), the arborist is able to create a comprehensive report that offers a complete analysis of each tree and its risk of failure.

Photos: Arborist Dan Dalton using a Resistograph to inspect a tree for internal defects and structural issues. See sample readings in the graph below.