ArticleTrees are frequently removed by cutting near the base of the trunk; this is commonly known as Tree Felling. This form of tree removal is physically challenging and can be dangerous if the process is not adequately planned and executed. In this article, Board-Certified Master Arborist, Mark A. Webber discusses tree felling and the importance of proper tree selection, inspection, work positioning, and tree felling techniques.
The experts at Robson Forensic are frequently retained to investigate injuries and deaths involving tree felling operations. Experts involved in these matters may include structural engineers, materials scientists, or board-certified master arborists. Contact us directly to discuss your case and determine which Robson Forensic expert is best qualified to assist.
Tree Felling Investigations
Felling of trees is one of the most common tasks performed during logging and arboricultural operations. It is a difficult and potentially dangerous operation that requires the sawyer (chainsaw operator) to have knowledge of trees, be physically fit, and be trained in tree felling operations.
The most common technique used in felling a tree is a multi-step process that first involves the creation of an open-faced notch in the trunk. In properly executed cuts, the creation of the notch positions the static load of the tree such that the sawyer, through the use of the back cut and the remaining hinge, can reliably control the direction the tree will fall. However, mistakes made during felling can result in property damage or serious injury/death to the feller or bystanders.
Safe felling operations begin with proper inspection of the tree and of the conditions in an area 2.0 times the height of the tree to ensure it is free of people & property. The next step used in felling a tree is making three precise and strategic cuts. The graphic below depicts a “conventional” notch, but other notch styles are utilized depending on the circumstances of the cut. Sawyers must make informed decisions regarding the style of notch, as well as the depth of each cut to safely and reliably fell trees.
- the Horizontal Cut
- the Sloping Cut
- the Back Cut
These cuts should be done by a sawyer who has been trained and wears the appropriate personal protective equipment like gloves, eye protection, hearing protection, head protection with face shield, chainsaw chaps, and steel-toed boots. The chainsaw selected for felling trees must be the appropriate size (bar length) for cutting the subject tree and must be sharp and in good repair. Having the appropriate equipment like tree felling wedges, taglines, and other tree felling gear may assist in the efficient and safe felling of trees.
The first step in felling a tree is for the sawyer to look for a straight tree and has an equal size diameter that is free of bulges or irregular architecture. If the tree is leaning or has a slight lean the sawyer should use a level or a plumb line to determine how much lean and what direction it leans. The sawyer should plan the felling operation in the direction of the tree’s existing lean. Trees with structural defects are potentially dangerous candidates for felling. Trees with spiraling of the bark indicate spiraling of the interior wood grains, which may make it difficult to control the direction of the fall. Trees with dead branches or pockets of rotten wood are also difficult to fell by conventional notch and drop operations. The sawyer should examine the base of the tree. If the base is hollow or one side of the tree has rotten wood, it may not be a suitable choice for felling operations since the rotten wood will affect the direction that the tree falls.
The next step is for the tree sawyer to determine if the path of the tree’s intended fall is clear of obstacles and targets. No persons or valued targets should be in the pathway of a tree being felled for a distance of at least 2.0 times the height of the tree from the subject tree’s base (see Drop Zone photo).
The tree sawyer must have a free and clear path to escape when the tree is being cut and when it begins to fall. The tree sawyer should make sure there are no obstacles like buildings, trees or other physical barriers that will block his/her to escape if the tree begins to fail without warning during the cutting operation. The pathway of escape should be at a 45 degree angle (see photo below) in either opposite direction of the intended direction of the felling path and at least 20 feet from the base of the subject tree being felled (see photo below). The tree sawyer should always assume that the tree will fall in EVERY possible direction and take measure to ensure nothing can be harmed regardless of which way the tree falls. The tree sawyer must plan two retreat routes to use when the cut tree begins to fall.
Preventable and Foreseeable Damages, Injuries and Deaths
Tree felling is a difficult and dangerous operation that should only be undertaken by individuals who have the proper training and experience. A single mistake made during a tree felling operation can result in damage to property or serious injury or death to the tree feller or bystander. The safe felling of a tree includes proper tree and site inspection and conformance with applicable standards for work positioning and cutting. The vast majority of injuries and incidents can be prevented if these standards and techniques are followed.
FORENSIC TREE INVESTIGATIONS
Among our tree experts, you will find a Board-Certified Master Arborist, a Professor of Forestry, and a group of facility operators who specialize in the maintenance of commercial, industrial, and recreational properties.
Within the context of a Tree Felling investigation, Robson Forensic is positioned to provide a thorough and comprehensive investigation by addressing every aspect of the case, from structural engineering and materials failures to specialty aspects of tree forensics.
For more information submit an inquiry or contact the author of this article.
Board-Certified Master Arborist & Horticultural Expert
Mark Webber is a Board Certified Master Arborist and a Certified Professional Horticulturist with nearly forty years of relevant professional experience. He provides expert witness investigations, reports, and testimony in matters related to tree condition, maintenance and removal; management of nursery, arboricultural, and landscaping operations; and an assortment of horticultural issues.