Movement and work in the tree using DdRT and SRT with the ZIGZAG - Petzl Netherlands
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Movement and work in the tree using DdRT and SRT with the ZIGZAG

The ZIGZAG may be used on doubled rope (DdRT) and on single rope (SRT) when combined with the CHICANE. Each technique has advantages and disadvantages depending on the situation.

Warnings

  • Read the technical notice before viewing the following techniques.
  • It is important to fully understand the information provided in the technical notice before using this complementary information
  • Mastering these techniques requires training.
  • Consult a professional before attempting to perform these techniques on your own.



Note: in this document the name ZIGZAG means either the ZIGZAG or ZIGZAG PLUS models.

Installing the work rope

Installing the work rope, DdRT.
  • The arborist selects an anchor on-site and installs it as high as possible in the tree, for optimal movement.
  • Provides tree access for multiple arborists
  • The access rope can be used for rescue or as a work aid by the person on the ground.
  • The top of the tree must be reached before work can begin.
DdRT logo.
Installing the work rope, SRT.
  • Ability to work anytime during access.
  • Ability to work without climbing to the tree-top.
  • The rope may be set up on a releasable anchor, to facilitate rescue.
  • Difficult to check anchor quality before use.
  • Using an anchor set by the throw line, which is not necessarily the best nor the best placed.
SRT logo.

Equipment to use

Equipment to use, DdRT.
DdRT logo.
Equipment to use, SRT.
SRT logo.

Areas of the tree accessible from the selected anchor

Areas of the tree accessible from the selected anchor, DdRT. Reduced efficiency and fluidity of movement without a straight rope between the anchor and the arborist.
DdRT logo.
Areas of the tree accessible from the selected anchor, SRT. Efficiency is unaffected by bends in the rope.
SRT logo.

Efficiency and ergonomics when returning to the trunk

Efficiency and ergonomics when returning to the trunk, DdRT. Pulling on the brake-side rope in double mode provides a self-hauling effect. The rope serves as a fulcrum and reduces the effort needed to climb.
DdRT logo.
Efficiency and ergonomics when returning to the trunk, SRT. Without a special setup, the arborist pulls 100% of his weight when pulling on the rope.
SRT logo.

Load on the anchor

Load on the anchor, DdRT. The arborist is suspended directly; the load on the anchor is simple.
DdRT logo.
Load on the anchor, SRT. The load on the anchor is theoretically doubled by the “pulley effect” at the rope’s redirect point (depending on the friction at the redirect). Note: this point will be elaborated in another technical tip as practice can differ significantly from theory.
SRT logo.