Timber extraction by cable yarding on flat and wet terrain: a survey of cable yarder manufacturer’s experience

Abstract

Highlights• Survey of all European cable yarder manufacturers on flat-terrain yarding.• Manufacturers are frequently contacted concerning flat-terrain yarding.• Forest resource inaccessibility, regulatory and environmental considerations are most important motivations. • Lack of clearance, tree stability and installation costs are major challenges.• Mobile, self-anchoring tail spar is considered a chief adaptation.• Cost-competitiveness with ground-based systems cannot be achieved without subsidies.• Increasing environmental awareness and climate change present opportunity to expand flatterrain cable yarding. AbstractCable yarding is a general solution for load handling on sites not accessible to ground-based machinery, and is typically associated with steep terrain. On flat terrain, such conditions can primarily be found on soft or wet soils, most frequently encountered in Central and Northern European countries. Today, changed environmental and market conditions may offer an unprecedented opportunity to the actual implementation of cable yarding on flat terrain in commercial operations. The study goal was to collect cable yarder manufacturers experience regarding the use and adaption of cable yarding technology on flat terrain. European manufacturers of cable yarding technology were interviewed about customer experience, particular challenges, adaptation potential, future potential and main hurdles for the expansion of cable yarding on flat terrain. Almost all manufacturers have received requests for flat-terrain yarding technology solutions, primarily from Germany. Temporal or permanent inaccessibility, regulatory or environmental reasons were the most frequent motivation for considering cable yarding technology. Installation was considered particularly challenging (clearance, stable anchoring). Potential adaptations included higher towers, artificial anchors, mechanized bunching before extraction and un-guyed yarder-systems. An artificial, highly mobile, self-anchoring tail spar was considered the most useful adaptation. While concerned about limited profitability and qualified labour shortage, most manufacturers demonstrated a positive or neutral view concerning the expansion of cable yarding on flat terrain. However, cable yarding is not considered to be cost-competitive wherever ground-based systems can be employed and cable yarding is not subsidized.

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

“…For that reason, double-hitch carriages could represent an especially valuable addition to conventional sled-winch operations, which are still very popular in the Alpine area (Spinelli et al 2013). Furthermore, double-hitch horizontal suspension would be crucial when extending cable yarding to flat terrain at sensitive sites (Erber and Spinelli 2020). In any case, it is worth noting that double-hitch carriages are designed by fitting a conventional motorized dropline carriage with a dedicated extension: the main investment remains that of the base carriage, which can easily swap configurations, thus adapting to highly variable terrain conditions.…”

A Literature Review on Cable Extraction Practices of South Korea: 1990–2020

“…Excavator-based un-guyed tower yarder technologies were described in the USA in 1990 and required lower investment, fewer human resources and landing area requirements, and installation was more rapid than for other tower yarders [44,45]. Therefore, in Korea, two types of excavator-based tower yarders were imported and developed to operate in clear-cut and thinning treatments between the 2000s and the 2010s.…”

Advances in Cable Yarding: A Review of Recent Developments in Skyline Carriage Technology

“…Even where full suspension would not be indispensable to technical operation, minimum ground contact would have the advantages of lower soil disturbance and wood contamination-the latter being especially valuable in the case of biomass recovery [60]. For that reason, doublehitch horizontal suspension could be considered crucial to extending cable yarding to sensitive sites on flat terrain [18].…”