Tensile Strength of Ropes and Friction Hitch Used in Tree Climbing Work

Leonardo Bianchini,Andrea Colantoni,Rodolfo Picchio,Marco Scotolati,Massimo Cecchini,Valerio Di Stefano

doi:10.3390/f12111457

Abstract

Tree climbing techniques for arboriculture are becoming more and more popular, but like any work activity, there are risks for the operator. The PPE (personal protective equipment) and protective systems studied here include semi-static ropes and friction hitches. The work rope/friction hitch system is a combination that many operators rely on, but unlike current mechanical rope clamps and descenders, they do not have European certifications. For this reason, tensile tests were carried out using a traction bench on rope/knot systems. Two rope models and two types of knots were used to stress the systems and materials as much as possible, so as to observe the resulting ratios. A total of 36 tests were carried out in which measurements were taken, including applied load in traction, knot creep, and rope diameter changes. Several results were obtained, including a maximum load of 18.7 kN, a maximum slip of 9.6 cm and a maximum diameter variation of 3 mm. This work represents a preliminary investigation for verifying the relationship between work ropes and friction knots. Relationships among the variables were observed; differences emerged mainly as a function of the type of knot used rather than the type of rope used. The data obtained is also important for applications towards improving preventative safety measures.

Highlights

Arboriculture, better known as “urban forestry”, is an area that is making great strides in scientific research and technical solutions [1,2,3]
The goal of this work was not to define the best knot to use, but to pave the way for a series of studies in order to understand the behavior of friction knots and to define which types of rope are best for combination with such knots—both in terms of size, and in the future, in terms of material
It is important to understand the characteristics of the knots in terms of strength and behavior in order to comprehend the tolerance levels of the system—this leads to various and sometimes conflicting notions and information among climbers, which cannot be backed up by reliable sources

Summary

Introduction

Arboriculture, better known as “urban forestry”, is an area that is making great strides in scientific research and technical solutions [1,2,3]. A growing focus on the proper planning and management of trees in the city or urban–forest interfaces has led to an increased need for technicians and operators employed in this sector [4]. Operators are exposed to a multitude of risks, given that they work at considerable heights. As noted by several authors, this typology of arboriculture is a dangerous activity, with a high number of injuries every year occurring in many countries [5,6,7,8]. Pruning and controlled felling (rigging) are the most common and frequent practices, which in these contexts require work “in canopy”. Among the various techniques for reaching the tree canopy, rope-based methods are the most commonly applied in tree climbing

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Conclusion