ASWP03 Ascending Trees
Note: During the tree inspection, discovery of structural defects or potential hazards will
require careful reconsideration of the methods originally selected for use. It may be necessary
to select an alternative method for accessing the tree.
4.2.1 Anchor Strength Assessment
Many factors determine tree branch breaking strength. Listed below are descriptions of the
most common conditions that could produce a limb failure.
Magnitude and type of load (e.g. dynamic vs. static) applied
Type of loading (distance away from limb attachment to main stem)
Other loads on the limb (foliage, snow, torque caused by limb length, weight
distribution, etc.)
Tree species
Cross sectional area of solid wood (diameter of limb)
Condition of wood (sound, decayed, hollow)
Branch attachment relative to parent stem (angle, "V" or "U" shape)
Season and temperature (winter versus summer)
Stage of tree maturity
Movement or rubbing between limbs
Assess the above conditions prior to using a limb as an anchor point. Some of the listed
conditions can be scientifically proven without severing the limb from the tree. However, in
most cases, combined knowledge and experience will prepare the arborist to determine
whether the limb is safe to use as an anchor point. In the absence of adequate knowledge
and/or experience, the arborist should request assistance from a more qualified person with
respect to this decision.
In order to minimize the effect of leverage on the limb being used as an anchor, the arborist life
line should be kept against the main stem of the tree while climbing. To facilitate this, limbs
used as temporary anchor points must be horizontal or growing upwards.
Page 30
