A plan of some sort, no matter how simple, is crucial to accomplishing any task, and tree work is no exception. In fact, given the inherent dangers and hazard of tree care operations, the case can be made that planning is even more important and crucial to safe, efficient operations in the tree care profession.
Look closer at some tree work activities. Felling — getting an upright tree on the ground where you want it, when you want it, and in the manner you want it — cries out for some type of planning process. This process does not need to involve lots of paperwork or entering items into the latest hand-held electronic device; in fact, the simpler the better. Once established and understood, the planning process should take place every time prior to a saw touching wood.
This column discusses the use of a simple five-step plan for felling trees that can be easily adapted to other cutting situations, both at ground level and aloft, and should be to ensure that crew members are aware of, and prepared to deal with, the hazards of any cutting situation.
Discussing the plan verbally will ensure understanding and communication amongst all crew members, but the process and framework is simple enough that it can be gone through mentally by the operator once practiced for a bit.
The five-step felling plan, as the name suggests, has five key components: height and hazards, lean, escape route, notch and hinge and backcut. Each of these components helps with the next step. Whether or not this particular process is used, any cutting/felling plan should consider and encompass some form of these five components.
Height and hazards
The plan’s first step, although simple, is vital. Has the crew truly looked at what hazards there are that might affect getting the tree on the ground? Will it fit in the place the crew wants to put it? Will felling the tree create or magnify existing hazards to the point they will adversely affect the crew?
Hazard information can be gathered by outer and inner perimeter visual inspections, pull/load testing with throw line, and even more invasive techniques such as drill or bore cut testing for sound wood fiber or root collar excavation. The goal of looking for hazards is to avoid nasty surprises in the midst of felling, when it’s too late to try to mitigate for them. The height of the tree can be pretty accurately and simply determined through the use of stick height estimation, or by using a clinometer or range finder. It’s not important how technical the method used to estimate height and hazards is, but rather that height and hazards are examined and made a part of the plan.
Side, back or front lean all influence the felling of a tree, so this information is vital. Simply looking at the trunk to try and estimate a tree’s lean can be deceiving. A better method is to step back from the tree and estimate its lean by looking at the entire biomass. The straight line coming down through the center of the biomass gives a pretty accurate idea of how much lean the tree has, and can give the chain saw operator an idea of how many feet of lean he will have to overcome with felling techniques.
Front or back lean is best estimated off to the side of the tree, or 90 degrees from its intended felling direction, while side lean is best estimated looking at the tree from the intended landing zone. Crews should keep in mind that side lean is safe felling’s biggest challenge and try to set up their plan accordingly.
Figuring out, setting up and using an escape route greatly increases the safety and survivability of a feller. Studies have shown that 90 percent of injuries/fatalities that happen during felling operation happen during the first 15 seconds of movement within a 5-foot circle of the stump. Getting out of that 5-foot circle safely and efficiently cannot help but increase the operator’s safety, particularly when an escape route has been chosen and prepared ahead of time.
The opposite direction from the fall of the tree is not a good choice for an escape route due to the possibility of tops breaking out or the trunk kicking backwards off the stump. The best choice is at a roughly 45-degree angle back and away from the direction of fall. If side lean does exist, that side should be designated the “bad” side of the tree, and the escape route should be on the opposite side. Obstacles, roots, stones and other hazards along the escape route should be removed or taken into account as part of this step in the plan.
Notch and hinge
The face notch is the directional felling cut into the side of the tree. It consists of two cuts and should “face” the intended direction of fall. The hinge, which is located behind the apex of the face notch and in front of the later backcut, may be thought of as a long board that runs from the base of the tree to the top and is bending/controlling the tree or piece as it falls.
If the hinge has good wood fiber, it will not break until the face notch closes, thus controlling the direction and fall of the tree somewhat, particularly if not too much side lean is present. The open-face notch will provide the maximum amount of control possible. Regardless of which notch is used, bypass, or cutting past the notch into the hinge, is to be avoided or cleaned up whenever possible. Bypass will prevent the face notch and hinge from working correctly and cause the hinge to fail early, removing all control of the large, woody mass heading toward the ground.
This step is when the operator determines which cutting method he will use to establish the hinge and release the tree on its merry journey to the ground. It also includes determining and employing additional means/methods to overcome back lean, or prevent barber chair in the event of severe forward lean.
The hinge thickness should be between 5 and 10 percent of the diameter of the tree, although this will depend on the species and situation. Additionally, the hinge should never exceed 2 inches in thickness. Even width or thickness along the length of the hinge will provide maximum control. Leaving it thicker or thinner on one side or the other means the hinge simply breaks later or earlier on that side. The only way to “steer” a tree with hinge thickness is to be in there cutting as it comes over, and that puts the operator within that 5-foot circle in that first 15 seconds where 90 percent of the really bad things happen.
A short, stocky tree or piece will require a much thinner hinge, as once again the hinge is a board that is bending, and it’ll be much easier to bend, without breaking, a 10-foot-long board that is .5 inch thick than one that is 2 inches thick.
Using a bore or plunge cut to establish the hinge is a safe and accepted practice, and in many cases is recommended due to its ability to prevent barber chair. Training and practice on the bore cut technique is vital prior to using it in actual field operations. Operators experienced in and choosing to use the bore cut would be well advised to start their bore back from the desired hinge thickness, giving themselves space to adjust or even rebore to establish the correct level and angle of cut.
Users employing the conventional or 45-degree face notch should use a “stepped” backcut in which the backcut is elevated slightly – 1 to 2 inches – above the apex of the notch. This step will create a ledge, helping to prevent the tree from kicking back off the stump when the hinge breaks as the face notch closes. When using a “stepped” backcut, operators must be careful to estimate hinge thickness from the apex of the notch, not from the front of the face, as doing so from the face can lead to the hinge being cut.
Operators using an open face or 70-degree notch do not need to worry about “stepping” their backcut, as the tree will have already passed through the angle of maximum push backwards before the notch closes and breaks. As mentioned earlier, this is also the time where wedges, pull lines and other means of overcoming lean are decided upon and put in place.
This plan, with its simple five-step format, once understood and made part of daily work practices will increase both the safety and efficiency of felling/cutting operations. In addition, the plan allows tree crews to easily and quickly examine and consider the various hazards and challenges presented by felling a tree, and thereby come up with a way to deal with them. Surprises are fun in many aspects of life, but, in general, tree felling or cutting is not one of them. The use of a systematic, well thought-out plan can help eliminate those nasty surprises.