Natural Notes: Climbing and Working in Trees

This post consists of my notes from a lecture on climbing and working in trees as part of my training to become a certified arborist by the International Society of Arborculture.  The speaker was Phillip Prohaska, a natural resources specialist with the Forest Preserves of Cook County and his lecture took place on February 27, 2015 at the Salt Creek Resource Management facility in Willow Springs, Illinois.  Please note that some graphics in this post were used from outside sources.  

A tree climber's safety relies on the integrity of the PPE being used, such as climbing saddles, snaps, and carbiners (climbing equipment).  Both carbiners and snaps must have a minimum breaking (tensile) strength of 5,000 pounds (table A).  Caribiners should be auto-locking if used for climbing purposes (figure 1).  
Table A
Figure 1:  Carabiner

 Ropes must have a minimum tensile strength of 5,400 pounds and must be identified by the manufacturer as suitable for use in climbing.  A synthetic material is required, as natural fibers are too weak.  

 When inspecting a climbing rope, the tree worker should ensure that the diameter of the rope is consistent and that there are no excessively frayed segments.  Figure 2 shows what too look for when inspecting the condition of a climbing rope.  
Figure 2:  Inspecting a climbing rope



 There are design limitations for climbing ropes.  Each time the rope is used, fibers are further worn.  Workers must agree on what the upper load limit, or the working-load limit (WLL) is in order to increase the lifespan of the rope.  Using a climbing rope at its working load limit (such as those listed in table A), then it could fail after one use.  

 A work-positioning lanyard is sometimes used in tree climbing often as a secondary means of attachment,  

 Climbing ropes have a working-end and a running end.  Figure 3 shows where the load and fall areas are on a climbing rope.  
Figure 3:  Load and fall areas on a climbing rope

 Different hitches and bends, which are categories of notches, are presented in figures 4-8.  A climbing hitch is a type of knot used to allow for climbing upwards and downwards.  A bowline is one of the more common knots used in arborculture as it is easy to untie (see figure 7).  A prusik hitch uses friction for both climbing and rigging actions (it's bidirectional) (see figure 8).  


Figure 4:  (A) a figure-8 knot, (B) a midline clove hitch, and (C) sheet bend hitch

Figure 5:  Tautline hitch
Figure 6:  Blake's climbing hitch

.  
Figure 7:  Bowline hitch.
Image source:  http://www.handymanhowto.com/how-to-build-a-rope-tree-swing/

Figure 8:  Prusik hitch.
Image source:  http://www.animatedknots.com/prusik/

When tying in, it is important to tie in on the most central, high location on the tree as possible (figure 9).  
Figure 9:  Tie in at the most central and highest location
When selecting a crotch to support a climbing rope, pick the larger of the limbs for optimal support (figure 10).  If an acceptable crotch is not available, the climber can make a false crotch using anything that can take the place of a natural tree crotch (figure 11).  Double crotching is the use of both ends of a climbing line as points of attachment.  This method is used to help climbers adjust their angle safely when cutting as it adds another climbing system that allows for more maneuverability.  
Figure 10:  Crotch selection

Figure 11:  False crotch
A chainsaw lanyard prevents the saw from dropping.  It catches the saw on its way down.  The lanyard must be long enough to stretch from the handle of the saw to the person cutting plus some extra length for slack.  

 Emergency response and aerial rescue operations must be initiated immediately during an emergency (why would you wait??).  It is a good idea to keep a list of emergency phone numbers handy.  Before performing a rescue, be sure that there are no electrical hazards present.  If there are no electrical hazards, check the victim's condition before beginning a rescue operation.  Make sure that the victim's safety equipment is secure, and keep a rescue kit handy with extra climbing gear.  

 Climbing ropes have an ideal bend ratio of 4:1 (see figure 12).  

 A snap cut is where a saw can get stuck when cuts are bypassed (figure 13).  








Figure 12:  Climbing ropes should have a 4:1 bend ratio.  

Figure 13:  Snap cut



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