Tree Felling

Evidence shows that felling a tree is one of the most dangerous activities any person can perform. It does not make a difference if you are a landscaper, arborist, logger, municipal worker or a weekend warrior - when you pick up a chainsaw to cut a tree down, you are entering a dangerous arena.

Typically the more dangerous we perceive something to be, the better we plan to protect ourselves. If we are unaware or have no reason to think what we are doing is dangerous, then we work out of ignorance. In this article, I would like to explain the risks associated with tree felling and share two simple ways to improve your personal safety when felling a tree.

Tree felling accident reviews have revealed certain patterns and regularities. There are some very interesting common factors to almost all tree-felling accidents.

90% of the accidents occur within the first 15 seconds of the tree falling and within a 5-foot radius of the base. I like to call this the '5-15-90 RULE'. What we can learn from this is how important it is to have an escape plan and use it whenever falling a tree. Always clear an exit path and practice walking down it a couple times prior to falling the tree. As soon as the tree begins to fall you want to get more than 5 feet way in the direction of your exit path, in less than 15 seconds. If you do this you can reduce your chance of being killed or injured by 90%. Your exit path should be at either a 45 degree angle opposite the direction of fall or 135 degrees from the direction of fall, as shown in the diagram. This escape strategy comes also from accident reviews and records that show how many times when a tree 'barberchairs' or comes off a stump prematurely it often lands behind the stump opposite the direction of fall.

A common cause or reason why trees can jump off the stump or fall off course is from premature hinge failure. The hinge is the wood left uncut behind the notch and in front of the back-cut. The hinge provides control during the arc of the fall, so that the longer the hinge remains intact and working, the more control there is during the fall of the tree. Typically trees are perpendicular or 90-degrees to the ground. Based on this it makes sense that a hinge would have to bend or hinge through an arc of about 90-degrees and the only way this is possible is if the notch aperture or opening is 90 degrees also. Often I see notch openings cut in trees much less than 90 degrees and even down to 45-degrees. A notch much less than 70 degrees does not allow the hinge to work or control the falling tree to the ground. Remember the more open your face notch is, the longer the hinge can provide control. This type of notching is called an 'open face notch'.

In conclusion, two simple thoughts on how you can improve your safety when falling trees are: 1) Plan - establish and use your escape route, and 2) Use an open face notch in order to maintain more control of the trees you are falling.

Dwayne Neustaeter, President, Arboriculture Canada Training & Education Ltd.