What are tree cabling systems?

“Tree cabling systems are connections between crown parts that are at risk of breaking off. They are to prevent one or more crown parts from breaking off or falling.” German Treecare Standard (ZTV Baumpflege)

IntroducTion Video

cobra® tree cabling system

- the right system for every tree -

Basic questions

The same questions crop up time and time again if a tree is being restored to be safe for traffic and pedestrians using tree cabling systems:

Is dynamic or static tree cabling required?
Which breaking load is required?
Where should the tree cabling be installed?
What do I need for this?

Our answers

dynamic or static tree cabling

In most cases branches/stems are supported using dynamic cabling. This is installed as horizontally as possible and ideally as triangle cabling. This type of cabling supports all wind load directions.

Static cabling is only installed if a branch is cracked. This is also installed as horizontally as possible and as triangle cabling.

Wide branches or branches where cabling against side wind loads is not possible are secured using static support/load cabling. With this the tree cabling runs as vertically as possible and is not to prevent breakage but to prevent it from “falling to the ground” afterwards.

Recommended breaking load

As a rule, no complicated calculations or analysis are required here. In practice we rely on arborists’ decades of practical experience. The ZTV Baumpflege standard’s notes on breaking loads for crown bracing apply here.

German treecare standard (ZTV Baumpflege) note on calculating dynamic tree cabling systems:

Branch/stem diameter (measured at the base at the time of installation)	Minimum breaking load for the warranted service life, installed at least in 2/3 of the branch/stem length to be cabled
up to 40 cm	2,0 t (cobra 2t)
between 40 and 60 cm	4,0 t (cobra 4t)
between 60 and 80 cm	8,0 t (cobra 8t)
over 80 cm	Special situations to be decided on a case-to-case basis

German treecare standard (ZTV Baumpflege) note on calculating static crown bracing and load/support cabling systems:

Double the values for tree cabling systems that are to keep part of a tree still or absorb permanent loads.

Recommended installation position and height

It is also recommended that the German treecare standard (ZTV Baumpflege) recommendations are followed here.

If the installation is on one level, then dynamic or static cabling is installed at least at 2/3 of the height of the branch to be cabled.

If the installation is on two levels (with split forks), then static cabling is installed at least at 1/4 of the height and dynamic cabling is installed in 2/3 of the branch to be cabled.