Safety assessment of trees used as anchors in cable-supported tree harvesting based on experimental observations

Marchi, Luca De; Mologni, Omar; Trutalli, Davide; Scotta, Roberto; Cavalli, Raffaele; Montecchio, Lucio; Grigolato, Stefano

doi:10.1016/j.biosystemseng.2019.06.022

Cited by 18 publications

(8 citation statements)

References 36 publications

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“…In turn, that supports the decision made by the European Standardization Agency (Technical Committee 144, Working Group 8) to decrease the skyline safety factor from 3 to 2.5 for those yarders equipped with a calibrated slip brake on the skyline drum, like the machines included in this and in the 2017 study. Of course, even if the level of overloading applied by the operators in these tests is likely representative of general practice, there will always be the occasional operator who may push the envelope (Marchi et al 2019;Mologni et al 2019). In that regard, it is worth recalling that the study was conducted during a salvage operation, where trees had not been felled systematically according to a welldefined plan but had been windthrown and were especially hard to disentangle.…”

Section: Discussionmentioning

confidence: 99%

Skyline tension and dynamic loading for cable yarding comparing conventional single-hitch versus horizontal double-hitch suspension carriages

Spinelli

Magagnotti

Cosola³

et al. 2021

International Journal of Forest Engineering

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Wire rope used in cable logging, where a series of cables facilitate the extraction of timber on steep terrain, experiences high tensions that must be managed to ensure safety. Innovations change practices over time and double-hitch carriages, which allow trees to be extracted horizontally, are a recent example. This makes it feasible to harvest across terrain with limited deflection, increases the recovery of biomass, and potentially reduces high-dynamic load events associated with ground contact. In this study, a standard single-hitch carriage was compared against a new double-hitch carriage under controlled conditions. Tension was measured continuously and specific elements, such as tension when the carriage was at midspan, maximum tension at breakout and inhaul, and magnitude of cyclic tension during inhaul were identified, measured and compared against payload. While payload was similar in the treatments, the additional weight of the double-hitch carriage resulted in higher skyline tensions. In both treatments, payload and skyline tension when the carriage was at midspan were strongly correlated. Cyclic tension was reduced by the double-hitch carriage system. While a number of unique high-dynamic loads were identified that were not part of the normal extraction, they represented only 6% of the cycles and the maximum tension was similar to that experienced during break-out and inhaul. This study increased the understanding of skyline tension during logging operations and the effect of carriage type. It showed that, though tension often exceeds the safe working load of the cable, it does not exceed the endurance limit for a well-designed and operated system.

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Section: Discussionmentioning

confidence: 99%

Skyline tension and dynamic loading for cable yarding comparing conventional single-hitch versus horizontal double-hitch suspension carriages

Spinelli

Magagnotti

Cosola³

et al. 2021

International Journal of Forest Engineering

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“…In addition, some researchers conducted non-destructive pulling test studies to predict the tree anchorage. Some predictive results have been obtained as well [21][22][23].…”

Section: Introductionmentioning

confidence: 90%

Application of Nondestructive Testing Technologies in Preserving Historic Trees and Ancient Timber Structures in China

Guan

Zhang

et al. 2021

Forests

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In China, preserving historic trees and ancient timber structures has attracted more attention from researchers and institutions. Nondestructive testing (NDT) technology has gained momentum in the application and research in recent years. This paper presents some examples of the application of NDT techniques in the protection of historic trees and ancient timber structures in China. A total of nine NDT techniques were applied, including five techniques of visual inspection, sounding, Resistograph, stress wave transmission velocity, stress wave tomography for both historic trees and ancient timber structures, two techniques of the pulling-test and ground-penetrating radar (GPR) for historic trees alone, and two techniques of acoustic emission (AE) and digital imaging for ancient timber structures. Based on field testing, there is a very good detecting effect for visual inspection and Resistograph, but sounding works unsatisfactorily. The stress wave transmission velocity is found to be excellent in screening for the internal defects of historic tree trunks, but performs badly in screening for the internal defects within the wood members of ancient timber structures. AE is less successful but digital imaging performs well in long-term monitoring and damage warning of wood structures. The stress wave tomography successfully obtains images of internal defects inside tree trunks. The anchorage of some historic trees cannot be quantitatively evaluated with the pulling test if the tree is too large. GPR’s resolution and accuracy are very low, which limit its application. Theoretical research on NDT and promotion of NDT technology are still an essential part of the work in the future.

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“…Failures of natural anchors, together with excessive cable tensile forces, are indeed primary safety concerns in all cable-supported harvesting systems (Tsioras et al 2011). Various publications have recently focused on assessing these safety concerns in cable yarding, both in terms of cable tensile forces (Harrill and Visser 2016; Mologni et al 2019Mologni et al , 2021b as well as anchor stability of various cable yarding operations (e.g., Mancuso et al 2018;Marchi et al 2019Marchi et al , 2021. While cable tensile forces can be effectively monitored and eventually controlled, anchor loading capacity is still largely overlooked because of the missing availability of operational solutions for their actual assessment and monitoring, and still too little is known about the behavior of trees and stumps used to anchor cables (Cavalli 2012; Marchi et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Cyclic loading effects and stability assessment of trees and stumps used as anchors in cable yarding operations

Marchi,

Mologni,

Byrne

et al. 2024

Preprint

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Swing yarders in running skyline configuration using either grapples or chokers represent the most common configuration for cable yarding in coastal British Columbia. In this context, whole-tree logging and short work cycles lead to heavy and repeated loads applied to the trees and stumps when used as anchors for the rigging cables. Moreover, increased harvesting of second-growth forest stands leads to the unavailability of large and safe trees, thus introducing new challenges to identify suitable anchors and potentially increases safety risks of cable yarding operations. The present study aimed to collect evidence of the mechanical response provided by anchors for typical cable yarders used in second-growth harvesting in coastal British Columbia, and test the suitability of innovative techniques for the stability assessment based on the relationship between the anchor root-plate rotations and the related applied tensile forces. A conspicuous dataset could be derived from all the surveys, storing anchor rotations from a total of 1522 work cycles of which 1224 work cycles included also tensions measurements. The methodological approach was proven effective for monitoring different rigging configurations giving proof that repeated loading affects the stability of a tree/stump which can rapidly change over few hours of active yarding operations. Acquired data proved also that comparing theoretical failure limits with anchor rotations could be a valid approach however a considerable amount of species-specific data from tree pulling tests is required.

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Safety assessment of trees used as anchors in cable-supported tree harvesting based on experimental observations

Cited by 18 publications

References 36 publications

Skyline tension and dynamic loading for cable yarding comparing conventional single-hitch versus horizontal double-hitch suspension carriages

Skyline tension and dynamic loading for cable yarding comparing conventional single-hitch versus horizontal double-hitch suspension carriages

Application of Nondestructive Testing Technologies in Preserving Historic Trees and Ancient Timber Structures in China

Cyclic loading effects and stability assessment of trees and stumps used as anchors in cable yarding operations

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