By Michael Tain
Spar pole rigging is a term used to describe the process of removing, under control by lowering pieces, a trunk with few, if any, branches remaining; with the pieces typically being rigged or lowered off anchor points on the trunk or pole itself. This process is probably one of the most commonly used techniques for removals in the tree care profession; and one that many climbing arborists “earned their spurs on” coming up early in their careers. Although spar pole rigging is a very common process in the industry, and a relatively simple system, it can be a process ripe with difficulties — and possibly catastrophic failure if improperly used or understood. The technical intricacies of spar pole rigging are better described through in-depth seminars, extensive articles with accompanying photos, hands on training, and/or instructional videos/DVDs. However, an understanding of some of the basic factors and considerations involved when using this process will assist climbers in employing it more safely and efficiently.
2-to-1 force factor: The 2-to-1 force factor, discussed in a previous column on rigging forces, is almost always present during the spar pole rigging process. Only the use of a separate tree — or another lead within the tree to be removed — as a higher anchor point than the piece being removed will eliminate the 2-to-1 force factor (although the location of the higher anchor point may introduce other possible rigging forces such as a bending moment). In the typical spar pole rigging system, the fact that the only possible location for the rigging block is beneath the piece being removed dictates that at least a 2-to-1 force factor will be present. This multiplication of force experienced by the anchor point, and the climber attached near it, will be magnified exponentially the further beneath the piece being removed the rigging block is located. In short, the greater the distance between the piece and the anchor point, the greater the force the anchor point will experience and the greater the ride the climber will experience. Prudence and professionalism dictates that this distance be as small as possible without adversely affecting the safety and security of the climber.
Force dampening/absorption: Scientific research and practical experience has shown that leaving branches, where possible, attached to the trunk of the tree being removed significantly lessens the forces experienced at the anchor point high up the trunk. Traditionally, climbers begin the removal process of a tree by removing all the branches as they ascend up the trunk; and then begin removing the remaining trunk or spar pole in pieces as they descend — commonly experiencing the “dancing” or “ride” of the pole as pieces are dropped into the system. By leaving branches on the trunk during ascent, climbers allow those branches to actually absorb and dampen some of the forces experienced by the trunk during rigging, lessening the forces experienced at the anchor point and trunk movement. Obviously, choices must be made on which branches to leave and remove during the ascent, but it is often possible to leave a “path” of removed branches to lower pieces through, thus assuring an efficient removal while still minimizing the forces experienced by the trunk.
Escape route: Just as an escape route is an integral part of any felling plan when removing trees on the ground, it is equally — if not more — important when aloft. Climbing arborists must have a means of quick, safe, and efficient descent to the ground in the event of an emergency or injury. Spur climbing in the descent does not qualify as a safe, quick, or efficient means of descent — particularly in the event of an injury. There are a variety of systems available that enable climbers on a bare trunk or spar to still be secured by a climbing system and have an adequate escape route. Among these systems are the adjustable Friction Saver, the running bowline static system, the Rope Guide, and the Monkey Tail system recently developed by North American Training Solutions’ lead instructor Odis Sisk.
Controlled lowering: The safe, controlled lowering of pieces, with a gradual deceleration rather than a sudden stop, will significantly lessen the forces experienced by the anchor point, the trunk, and the climber aloft. The use of any of the various lowering devices available — such as the Port-a-wrap III, GRCS or Hobbs — will result in smoother and more controlled lowering than the traditional “tree wraps.” Experienced ground personnel can certainly accomplish smooth controlled descents with “tree wraps,” but the use of lowering devices ensures the friction level is the same regardless of tree species. It also makes the operation more efficient by eliminating the tedious process of going around the tree with the rigging line again and again.
Chain saw techniques: Climbers are required to be secured by two methods when operating a chain saw aloft. This requirement is particularly important in spar pole rigging due to the typically close proximity of the climber’s system and the running chain saw. Additionally, the methods in which the cuts are made can be quite important in the reduction of trunk movement and anchor point forces. Operators familiar with the open face notch felling technique will find it equally applicable and efficient up in the tree as it is on the ground. However, the degree of opening should be carefully considered, as an opening too large could allow the hinge to still be attached after the piece has passed the horizontal plane, generating a pull forward on the trunk.
All of the topics discussed here, and many more, should be considered when carrying out spar pole rigging operations, but with knowledge and practice, this technique is an extremely safe and efficient tool in the climbing arborist’s mental toolbox.
Michael “House” Tain is a contract climber, splicer, educator and writer currently located in Lancaster, Ky. He can be reached via e-mail at firstname.lastname@example.org