SLIP SLIDIN’ AWAY-SLIDE LINES-Part I

Photo by Michael (House) Tain

Slide lines can save considerable time, energy and money.

Tree folk are confronted on a daily basis by the need to move something, usually awkward woody debris, from one place to another in an efficient manner. Often this involves a great deal of “sweat equity” with crew members physically carrying branches, logs and wood to the truck or chipper, typically with a fair amount of physical effort, energy expenditure and negative verbal commentary.

Slide lines, also often called zip or speed lines, offer another option for this debris movement. They’re an option that, though gear- and set-up-intensive, can be quite efficient, not to mention easier on a tree crew’s back and morale.

Port-A-Wrap

A Port-A-Wrap attached to the base of a tree with an eye sling. This piece of gear has excellent applications in slide lines, both for control line management and slide line tensioning.

Slide line use may be dictated by the worksite – for example, if there are hazards or obstacles immediately beneath or around the tree being worked on – or they simply can eliminate a long, tedious route of dragging debris to the truck or chipper. Slide lines often are used in concert with other techniques, such as balancing, lifting, knotless rigging and spar pole removal. Regardless of the application, the complex nature of slide lines and the forces they generate require an understanding of multiple factors to ensure their safe and efficient use.

Sometimes the “old school” method of just buckling down and sweating away at hauling that brush will be the safest and most efficient method. But, given the right situation, a knowledge of slide lines can get the job done safely and efficiently with energy savings all around.

Which line for sliding?

As is so often the case in tree care operations, one of the first questions to be answered in slide line use is which type of rope to use. Factors such as strength, elongation or stretch, and melting point all need to be considered, as they can have significant impacts on how well the slide line operation will go.

As an example, a line with more elongation will absorb energy more readily than a more static rope, but will require a great deal more input force, or pulling, to make it taut to “slide” loads down.

In turn, this requirement for more input force will require more time and energy, thereby making the use of the slide line perhaps not the quicker, more efficient choice it was meant to be.

Conversely, a very static line, or one with little elongation, will not stretch much when loaded, but will transmit all the input force to the anchor points of the slide line, possibly creating another area of concern.

Dynamic Loads

“Catching” a dynamic load prior to tensioning the slide line is key for safe use of this technique.

Only as strong as what it’s tied off to

The anchor points to which the slide line is tied or secured also must be evaluated in the use of this technique. The line carrying the load will have a lot of tension and force on it, both from the initial input force to make it taut and the weight of the load being transported. These factors will be transmitted directly to the anchor points at either end of the slide line.

Of particular concern is the anchor point aloft, especially when the point chosen is in the same tree to which the climbing arborist is attached, as it can create a bending moment that can cause failure in the tree itself. A better option is to anchor the upper end of the slide line into a separate tree, thereby avoiding any additional forces on the tree being worked on, although this might not be possible. Should a second tree be unavailable, or simply poorly positioned, the correct use of appropriate redirects can reduce the forces involved while anchoring the slide line adequately.

In addition, the lower anchor should be adjustable, so that tension can be applied and removed.

(Courtesy of Tree Services Magazine: http://www.treeservicesmagazine.com)