Pulling test: The effect of cut roots on safety factor

A brief case study by Tibor Horvath with Fakopp Pulling Test


  • The measured tree stood in a suburban garden and has been marked for removal.
  • The removal has been turned into a series of 6 pulling tests. First we measured the tree in its original state, then before every additional pulling test some of roots have been cut.
  • For the calculation of the safety factors, the wind speed of 33 m/s (cc. 120 km/h) has been used.
  • The purpose of the experiment was to reveal the effect of cut roots on the safety factor.

Safety factor measurements

Intact: 1.19

Excavated: 0.86

1 root cut: 0.61

4 roots: 0.33

7 roots: 0.27

All 11 roots: 0.14