Yarding Systems Research Articles

Measurement of Individual Tree Parameters with Carriage-Based Laser Scanning in Cable Yarding Operations

Introduction: Cable yarding is a technology that enables efficient and sustainable use of timber resources in mountainous areas. Carriages as an integral component of cable yarding systems have undergone significant development in recent decades. In addition to mechanical and functional developments, carriages are increasingly used as carrier platforms for various sensors. The goal of this study was to assess the accuracy of individual standing tree and stand variable estimates obtained by a mobile laser scanning system mounted on a cable yarder carriage.Methods: Eight cable corridors were scanned across two forest stands. Four different scan variants were conducted, differing in the movement speed of the carriage and the direction of movement during scanning. An algorithm for tree detection, diameter and height estimation was applied to the 3D datasets and evaluated against manual tree measurements.Results: The analysis of the 3D scans showed that the individual tree parameters strongly depend on the scan variant and the distance of each individual tree to the skyline. This was due to changing 3D point densities and occlusion effects. It turned out that scan variant 1, in which the scan was performed during slow carriage movement downwards and back upwards again, was advantageous. At a distance of 10 m, which is half of the recommended corridor spacing of 20 m for whole tree cable yarding, 95.44% of the trees in stand 1 and 92.16% of the trees in stand 2 could be detected automatically. The corresponding root mean sqare errors of the diameter at breast height estimatimations were 1.59 cm and 2.23 cm, respectively. The root mean square errors of the height measurements were 2.94 m and 4.63 m.Conclusions: The results of this study can help to further advance the digitization of cable yarding and timber flow from the standing tree to the sawmill. However, this requires further development steps in cable yarder, carriage, and laserscanner technology. Furthermore, there is also a need for more efficient software routines to take the next steps towards precision forestry.

Innovative Harvesting, Transport, and Yarding Systems in Forestry

2050 年のカーボンニュートラルの達成に向けて，CO2 の吸収源として森林が注目されている。しかしながら，日本の森林は半数が 50 年生以上の高齢級林であり収穫に適した時期を過ぎつつある。現在の森林を伐らずに維持することは将来的な森林での炭素吸収速度の漸減につながると予想される。したがって，今後森林を CO2 吸収源として持続的に維持するためには高齢級の森林の利用に加えて再造林を含めた森林の循環的な利用により森林の若返りを図り，さらに木材利用量を増やすことが重要である。また，今後人手不足が懸念される林業において森林を循環的に利用するためには，より安全で，より効率よく作業を行う必要がある。本稿では，森林の循環的な利用のために必要となる木材の伐採および搬出作業について，近年の自動化や新たな機械の開発の動向について示す。

Steep Slope Harvest System Models for Small to Large Trees

Background: Tethered cut-to-length and cable yarding systems with tethered falling equipment are increasingly used to harvest trees from slopes exceeding 30–60% more safely and at reduced financial cost than less mechanized harvest systems. Existing studies of harvest equipment typically isolate one or two pieces of equipment in a harvest system and often occur on sites with slopes below 50% and trees less than 60 cm in diameter. Methods: We analyzed machine capabilities and productivity regressions to extrapolate existing models to steep slope harvesting of trees up to 115 cm diameter. The resulting individual machine models are integrated into models of cut-to-length and long-log harvest system productivity. We estimated the financial operating costs of the harvest systems considered from equipment pricing and operator wages. Results: Analysis of even-age Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) rotations suggests eight-wheel forwarder productivity, swing yarder productivity, and mechanization of manual chainsaw labor with tethered harvesters as primary controls on harvest costs. Conclusions: The proposed model enables predictions across a greater range of slopes and tree sizes than those previously modeled, creating a foundation for future research into the cost and productivity of steep slope harvesting systems.

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

Cable yarding technology remains the most effective operation in steep terrain harvesting systems; however, it has limitations and challenges. Using cable yarders (tractor-, truck-, and excavator-based) to extract tree lengths and whole trees has been common since the late 20th century in South Korea, and cable yarding operations were developed in the late 1800s in the United States and Europe. Machine potential and limitations must be understood to ensure the widespread use of technology, strong cooperation, and optimal selection of machinery size. We reviewed the literature on tower yarder performances from 1990–2021 to determine the alteration of yarders and its productivity pattern and obtained 23 papers; <2 publications per year discussed the determination of cable yarding productivity. We selected independent variables (e.g., silvicultural treatment, harvesting method, and cycle log volume) for cable yarding that would likely affect productivity. Data were analyzed to compare productivities under silvicultural treatment, the harvesting method, and yarding direction and identify the interaction mechanical power (i.e., lifting capacity and machine power), yarding distance, and slope. Cable yarder productivity rates generally depended on the silvicultural treatment, harvesting method, and yarding direction, particularly in clear-cut, tree-length, and uphill yarding operation activities. The lifting capacity, machine power, and slope had no significant correlation with yarders’ productivity, particularly in thinning operations, whereas, in clear-cut productivity, it was influenced by these variables. The results contribute to improving operation activities for cable yarding systems and towards future research directions.

Developing an Automated Monitoring System for Cable Yarding Systems

Cable yarders are often the preferred harvesting system when extracting trees on steep terrain. While the practice of cable logging is well established, productivity is dependent on many stand and terrain variables. Being able to continuously monitor a cable yarder operation would provide the opportunity not only to manage and improve the system, but also to study the effect on operations in different conditions.This paper presents the results of an automated monitoring system that was developed and tested on a series of cable yarder operations. The system is based on the installation of a Geographical Navigation Satellite System (GNSS) onto the carriage, coupled with a data-logging unit and a data analysis program. The analysis program includes a set of algorithms able to transform the raw carriage movement data into detailed timing elements. Outputs include basic aspects such average extraction distance, average inhaul and outhaul carriage speed, but is also able to distinguish number of cycles, cycle time, as well as break the cycles into its distinct elements of outhaul, hook, inhaul and unhook.The system was tested in eight locations; four in thinning operations in Italy and four clear-cut operations in New Zealand, using three different rigging configuration of motorized slack-pulling, motorized grapple and North Bend. At all locations, a manual time and motion study was completed for comparison to the data produced by the newly developed automated system. Results showed that the system was able to identify 98% of the 369 cycles measured. The 8 cycles not detected were directly attributed to the loss of GNSS signal at two Italian sites with tree cover. For the remaining 361 cycles, the difference in gross cycle time was less than 1% and the overall accuracy for the separate elements of the cycle was less than 3% when considered at the rigging system level. The study showed that the data analyses system developed can readily convert GNSS data of the carriage movement into information useful for monitoring and studying cable yarding operations.

Potential application of synthetic fiber materials for guylines of cable yarding systems.

Potential application of synthetic fiber materials for guylines of cable yarding systems.

Challenging agent-based simulation for forest operations to optimize the European cable yarding and transport supply chain

ABSTRACT In the steep terrain of the European Alps, cable yarding still plays an important role. To maintain low costs of timber harvesting and improve the productivity of cable yarding operations, system integration by mounting of a tower yarder, crane, and processing unit onto a single carrier is the major pathway of innovation. In particular, under mountainous conditions, with small landings at the forest road and high production rates, cable yarding systems require well-coordinated transport to available storage space at the landing. Otherwise, the operation will run out of storage space and be shut down until serviced by a log truck. To investigate the system behavior and determine the overall performance effects, an agent-based simulation model was developed. The impact of the storage capacities, number of trucks employed, weather conditions, and timing of truck orders were evaluated. Cable yarders, trucks, and individual yarding lines form a population of agents placed in the spatial model environment, acting as the top-level agent. To harvest and transport an assumed volume of 52,500 m3 of timber from 65 different harvesting sites with 150 yarding lines, 301 days are required, in the best case. For the worst case, 484 days are required to complete all operations. Early information flow of the storage level at the landing saves a majority of the waiting cost if the storage capacity at the road is low and the number of trucks high, with 2.5 € m−3. The results also show that adopting measures to increase the storage capacity at the landing will lead to less sensitive reactions in the supply chain.

The Influence of Old and New Machines on Productivity and Costs of Four Yarding Methods in Small-Scale Forestry in a Maine Forest

Small forest landowners and loggers require information on the cost and productivity of available timber harvesting systems in order to make the best equipment allocation decisions, especially when the current generation of highly productive, capital-intensive harvesting machinery is well suited for clearcutting in large stands. Conversely, small-scale equipment is becoming more readily available that can help minimize the capital and operating costs associated with partial cuts and intermediate stand treatments or when operating in small-scale forests. The present study evaluated the productivity and yardings costs of four different yarding systems for old machines—a farm tractor, bulldozer, cable-skidder and forwarder—working in a group selection harvest of a mixed hardwood stand in the state of Maine, USA. A sensitivity analysis using the break-even technique and considering the same harvesting productivity and machines brands and models was used in this study to assess study differences between yarding machines costs in two different scenarios: old and new machines. Results indicate that the total machine and yarding costs for old machines were lower than for the new machines. For old machines, the yarding cost per unit delivered to the landing was lowest for the forwarder method ($2.34/m3) and highest for the cable-skidder method ($4.46/m3). In the case of new machines, the yarding cost per unit was lowest for the forwarder method ($3.95/m3) and highest for the cable-skidder method ($9.46/m3). The older machines might be a better option than new machines, particularly for small landowners who need to harvest small areas with low levels of harvesting.

Productivity and cost analysis of tower yarder systems using the Koller 507 and the Valentini 400 in southwest Germany

ABSTRACT Cable-based timber extraction offers some advantages with regard to impacts to forest stands and soils, and can be used under a wide range of conditions. It is important not only in steep terrain, but also increasingly in flat terrain when soils have low bearing capacity. In this study, utilization data from two commonly used tower yarding systems were analyzed: a tower yarder with a mounted processor (K507) and a medium-distance tower yarder (V400). Collected data included explanatory variables, such as the proportion of hardwood timber, length of skyline, direction of yarding and dimension of harvested timber. Data were analyzed with regard to the time required for machine installation including set-up and dismantling, machine productivity and resulting production costs. Possible combinations of machines and partial working steps were evaluated. Results indicated an increasing utilization of cable crane systems in horizontal yarding direction throughout the analyzed time period. Further, more time was required to process full trees when the K507 was used, although machine productivity increased. The proportion of processed timber that was hardwood significantly influenced installation times. Results demonstrated that, if the machines had above average productivity, total costs could be reduced in flat terrain by using a cable crane instead of conducting the extraction by skidders.

Productivity and cost of whole-tree and tree-length harvesting in fuel reduction thinning treatments using cable yarding systems

Cable yarding systems are often used to reduce hazardous fuels in dense overstocked forest stands on steep terrain (>35%) in the western United States. However, treatment costs tend to be high. The aim of this study was to broaden our knowledge by evaluating two different harvesting methods (whole-tree (WT) and tree-length (TL)) used for fuel reduction thinning treatment on mixed-conifer forest stand. Different harvesting methods greatly affected the productivity and cost of fuel reduction thinning, especially in felling and yarding operations. Total sawlog removal costs (stump-to-truck) were US$26.13/m3 in the WT-harvested unit and US$24.01/m3 in TL harvested unit. TL thinning resulted in higher felling time and lower production rate due to increased amounts of time for processing trees at the stump. In yarding operation, however, TL method had a higher production rate than WT method because TL method had higher number of pieces per yarding cycle. Processing production rates at a landing were relatively similar throughout treatments although trees in a TL thinning unit were already limbed and bucked at the stump. Loading productivity was consistent throughout treatments because loading occurred independently from other activities. For fuel reduction thinning treatments using a cable yarding system, TL thinning was more cost-effective than WT thinning if leaving tree tops and branches on site is acceptable from a fuels management perspective.

Behavior and assessment of mobile anchors in cable yarding systems

Cable yarding systems transport logs hoisted off the ground by a system of cables and a carriage that moves along the cable. Ground anchors are used at the end points to maintain sufficient tension between the two ends points of the cable and keep it in the air during operation. Traditional anchoring methods employ tree stumps, but as shorter stand rotations result in younger weaker stumps and because of the inability to visually inspect root structures to calculate a stump’s anchoring capacity, alternative methods of anchoring are being used more frequently. In this paper, the capacity of an alternative anchoring method, known as equipment anchoring or mobile anchoring, is assessed for guyline and skyline applications. Some critical components that are observed to influence anchor capacity are equipment weight, slope, blade embedment, angle of cable pull, and soil type. An analytical design solution for mobile anchor capacity is compared with the results of over two dozen field tests to determine the effectiveness of predicting anchor capacity. In addition to estimating the capacity of mobile anchors, a relationship between skyline and guyline loading recorded on harvest operations is analyzed.

Operative loading in cable yarding systems: field observations of static and dynamic tensions in mobile anchor systems

Cable yarding systems are an effective means of facilitating harvesting operations in steep terrain, but require sufficient anchoring for safe performance. Design and safe operation often dictates that cable loading remain at a safe level, yet the actual loads incurred for anchoring systems, particularly for “mobile” or “equipment” anchors, are ill-quantified. Furthermore, these anchors are subject to loading that is rather dynamic in nature, realizing impulse loads from various operation occurrences, particularly breakout. This study describes the measured static and dynamic cable loads during yarding for 21 mobile anchor systems operated by eight different contractors during active logging operations. The mean dynamic loading observed for guyline and skyline anchors was 49% and 44% greater than static tensions, respectively. Maximum dynamic loads exceeded approximately double static tensions. In the observed tests, cable tensions were well below the cable elastic and endurance limits but did approach the allowable tension in some cases. Although the monitored cable loads in this study were all within a safe range, the observed dynamic loads are useful guidance when considering higher static loads and consequently higher dynamic loads that may be unsafe.

STUDIES OF NATURAL- PRODUCTION ASPECTS OF MOUNTAIN LOGGING (ON THE EXAMPLE OF THE STATE ENTERPRISE "SLAVSKE FORESTRY")

The article presents the results of analytical studies of the natural-production conditions of management in the forests of a particular region. As initial data, the materials of the basic forest inventory of 2008 and reports on logging of the state enterprise Slavske forestry for 2010-2015 were used. Productive high-yielding tree stands of the I class and upper class of bonitet (79.1 %) is dominated in the enterprise. The third part of the forest is located on steep slopes. Medieval forest stands are predominate (42.2 %). The basis of the forest cover is formed by stand that includes spruce (73.6 %), where the average volume of ripe and overmature plantations consist 473 m3/ha. However, there is a low resistance of this specie to various pathogens of diseases and natural disasters. In recent years, there has been an increase in the volume of improvement thinning conducted on 84.0 % of all harvesting areas, where 68.6 % of the total volume of timber was harvested. The dynamics of the increase of the areas of sanitary felling is noted, which is associated with a large scale drying of spruce stands. The technological processes of logging operations at the enterprise are mainly based on ground aids of primary timber transportation, causing significant damage to the surface of the cutting area and the adjacent territories. Typically, a tractor trailing is used, with which 90.7 % of the total volume of harvesting is performed. The volumes of trailing by caterpillar and wheel tractors are almost identical. Less often, animal skidding (8.6 %) and cable yarding systems (0.7 %) are used. The distance of trailing of wood for all means of primary transportation exceeds the recommended values. The average distance of trailing by animal skidding on all type of cutting is 0.35-0.41 km. Caterpillar tractors on final cutting and improvement thinning have average distance of trailing, respectively, 1.48 km and 1.23 km. For wheeled tractors, the average distance of trailing on final cutting and improvement thinning is 1.26 km and 0.90 km, respectively. At the same time there are positive trends in reducing the distance of trailing on all types of cutting, connected with the construction of new forest roads. The main factor influencing the forest environment is the primary transportation of wood, the optimization of which is an urgent task for mountain logging.

Analyzing the Efficiency of a Start-Up Cable Yarding Crew in Southern China under New Forest Management Perspectives

This case study analyzed the performance of a start-up cable yarding crew in southern China through operational monitoring by consecutive time studies, long-term log book recordings and efficiency evaluation by stochastic frontier analysis (SFA). The crew, which used a KOLLER K303 H mobile tower yarder, was monitored for two years. During this period, detailed data recordings of 687 yarding cycles of 12 yarding corridors as well as log book recordings of an additional 1122 scheduled system hours (SSH, including all delays) were generated. Mean extraction productivity of the system ranged between 5.23 and 6.40 m3 per productive system hour (PSH0, excluding all delays), mostly depending on slope yarding distance and lateral distance. Corresponding gross-productivity ranged from 1.91 to 2.24 m3/SSH, with an overall mean machine utilization rate of 31%. Unproductive yarding times and delays associated with the relative low utilization rate were mainly caused by lengthy rigging processes, as well as organizational deficiencies and not yet fully developed skill sets of the operating crew. The latter was reflected in a mean efficiency effect frontier value of 0.62 based on evaluation of data sets of individual yarding cycles recorded during detailed assessments, suggesting a mean improvement potential of 38% based on the SFA, translating in a potentially achievable gross-productivity of 2.64 to 3.09 m3/SSH. We conclude that current local operating conditions including insufficient planning, implementation and logistics and in particular, frequent discontinuations of system operations of up to three months all resulting in generally low operation hours per shift and per year, inhibit efficient operations and rapid skill development. These circumstances also inhibit an economic utilization of the equipment. Nevertheless, from a technical perspective, yarding systems have a promising potential in southern China.

Cable yarding productivity models: a systematic review over the period 2000–2011

ABSTRACTThe efficiency of cable-based yarding systems has been studied extensively, resulting in numerous work productivity models (i.e. models predicting the ratio between output and time). Productivity models are used in both research and operations management, but are laborious to develop. Efficient use of existing models is essential, but there is a lack of overviews of available models. Therefore, work productivity models developed in recent years were compiled, with the aim of increasing their visibility, accessibility and comparability to potential users and other interested parties. This compilation should facilitate comparisons and evaluations of the models and their influential parameters, and the synthesis of existing models. A systematic review of the international scientific literature on cable logging published between 2000 and 2011 was performed. Twenty-one publications describing productivity models were identified. These publications originated from four different continents, with most coming from Asia (specifically, Turkey). Many similarities were found between the models. For instance, more than half use yarding distance as an independent variable, whereas lateral yarding distance and load characteristics were used in only a third of the models. However, there were also many differences in terms of modeling praxis, model features, included parameters and the units used. Analysis of the compiled models suggests some potentially fruitful directions for future work in the field of cable logging productivity. More generally, model compilations such as that presented herein enable a range of analyses and harmonizations that benefit all kinds of forest operations.

Predicting load path and tensile forces during cable yarding operations on steep terrain

Cable yarding systems constitute an adapted solution for steep-slope harvesting in mountain forests. However, it requires many specific skills for both forest managers and operators. The objectives of this research were to: (1) develop a CableHelp model for the set-up of cable yarding systems where inputs are operational field data and outputs are load path and tensile forces, and (2) to validate it with field experiments. The results show a high accuracy between the data predicted by the model and field measurements. Furthermore, this work stresses the importance of taking into account both the mainline effect and the friction between skyline and intermediate supports to properly calculate the skyline tension and load path. The CableHelp model shows great adaptability and ensures highly accurate predictions for any position on the line profile and for different configurations: single-span or multiple-span profiles, uphill or downhill yarding and for different kinds of carriage. A direct application of this research is to optimize the set-up of cable lines in order to reduce equipment wear, as well as operating cost, while respecting operator safety.

Challenges in Mechanization Efforts of Small Diameter Eucalyptus Harvesting Operations with a Low Capacity Running Skyline Yarder in Southern China

This case study examines the performance of the Igland Hauler employed in small diameter Eucalyptus clear-cut operations in Guangxi, China. A yarding crew of eight persons was monitored by a snap back elemental time study for 19.23 SMH (scheduled machine hours), with 159 yarding cycles and a yarded log volume at landing of 49.4 m³ solid over bark. A gross-productivity of 2.50 m³/SMH and net-productivity of 5.06 m³/PMH0 (productive machine hours excluding delay times) was achieved, leading to a machine utilization rate of 49.5%. The costs of the yarder and associated overhead as well as the personnel costs of a large crew with eight people sum up to extraction costs of 50.24 USD/m³. The high costs make it difficult to compete economically with the locally common manual extraction system as long as abundant labor at a low hourly rate is available in the region. Further performance improvement through skill development, but also technical and organizational system modification in conjunction with rising wages and decreasing labor force in rural primary production will determine the justification of employing such yarding systems. However, new silvicultural regimes with extended rotations and supply requirements of the forest products industry in China demand new operational systems.

A semi-greedy metaheuristic for the European cableway location problem

The Cableway Location Problem (CLP) is a facility location problem usually studied as a part of a hierarchical approach for large cable yarding systems outside of Europe. Small adaptable cable yard...

Analytical design for mobile anchor systems

Cable yarding systems are a common method for transporting materials in mountainous terrain in situations that do not allow for ground-based skidding, forwarding or shovel-logging. Cable yarding, although effective in steep locations, requires anchored guylines to support the skyline and operating lines. The skyline and operating lines rely on a fixed anchor, or tailhold, to provide adequate tension for effective yarding. Anchored guylines and skylines usually depend on available stumps or trees. Where these are not available, mobile anchors such as bulldozers can be used. Mobile equipment anchors have an advantage of known resisting capacity, as opposed to trees and stumps, but there are no well-defined design criteria for the application of the system. Here an analytical design solution for mobile anchor capacity is presented, based on force equilibrium analyses, and accompanied by a series of design charts. A moment equilibrium analysis involving vehicle center of gravity and anchor attachment points is used to bracket feasible designs. It is shown that when the guyline angle is relatively high, the primary factor in anchor capacity is equipment weight. At lower cable angles, the passive resistance of the soil in front of the blade can play a major role, especially with deeper embedment, stronger soils and with an uphill vehicle placement. Finally, the anchor attachment point must be kept relatively low to the ground, especially if smaller equipment is used as an anchor. The results demonstrate that use of equipment as a primary or auxiliary anchoring system can be effective when adhering to design constraints based on equipment and in-situ soil properties.

가선집재작업에서의 작업 생산성 및 비용 분석

본 연구에서는 임목수확작업에 사용되는 집재기계의 작업효율성을 분석하여 경사가 급한(<TEX>$20^{\circ}$</TEX> 이상) 작업조건에 적합한 가선계 집재기계를 선정하는데 기초 정보를 제공하고자, 타워야더(RME-300T), 트랙터부착형 집재기(일명 : 춘천집재기), 트랙터윈치(FARMI) 등에 의한 집재작업에서의 작업생산성 및 비용을 비교 분석하였다. 평균 흉고직경이 20 cm, 집재거리 60 m, 가로집재거리 10 m, 그리고 기계이용률이 70%인 동일한 작업 조건에서 작업이 이루어질 경우, 타워야더의 1일 집재작업 생산성은 <TEX>$33.04m^3$</TEX>/일, 트랙터부착형 집재기는 <TEX>$38.47m^3$</TEX>/일, 그리고 트랙터윈치는 <TEX>$14.17m^3$</TEX>/일으로 분석되었으며, 이에 따른 집재작업비용은 각각 25,105원/<TEX>$m^3$</TEX>, 20,520원/<TEX>$m^3$</TEX>, 37,835원/<TEX>$m^3$</TEX>으로 나타났다. 동일한 작업조건에서 집재거리에 따른 각 집재기계별 작업효율성을 비교하였을 경우, 집재거리가 40 m 이내로 짧을 경우에는 트랙터윈치에 의한 집재작업이 효율적이며, 40~140 m의 집재거리에서는 춘천집재기가, 140 m 이상의 장거리 집재작업에서는 타워야더가 가장 효율적인 것으로 나타났다. This study was conducted to provide field-based harvesting study information which can be used to select an optimal cable system for certain work conditions on steep grounds (> <TEX>$20^{\circ}$</TEX> ground slope) in Korea. To accomplish this study objectives, we evaluated three cable yarding systems (RME-300T tower-yarder, Chuncheon tower-yarder, FARMI tractor winch) working in typical work conditions for their yarding productivity and operational efficiency. Those yarders are commonly used for removing logs or trees on steep grounds in Korea. Under the same work conditions (average DBH of tree to be cut, 20 cm; yarding distance, 60 m; lateral yarding distance, 10 m; and machine utilization rate, 70%), the average productivities were <TEX>$33.04m^3$</TEX>/day, <TEX>$38.47m^3$</TEX>/day, and <TEX>$14.17m^3$</TEX>/day for RME-300T, Chuncheon tower-yarder, and FARMI, respectively. Our standardized cost comparison study also showed that the yarding cost was highest at <TEX>$37,835won/m^3$</TEX> with FARMI, followed by RME-300T at <TEX>$25,105won/m^3$</TEX> for the same work conditions. We found the lowest yarding cost with the Chuncheon tower-yarder at <TEX>$20,520won/m^3$</TEX> which was resulted primarily from high yarding productivity at the yarding distance (60 m). Our analysis suggested that a small machine such as FARMI could be a low-cost yarding machine option for a cable yarding job with a short yarding distance (40 m or less). The Chuncheon tower-yarder is well suited for a mid-range yarding distance job in Korea, ranged between 40 to 140 m. If yarding distance were longer than 140 m, the RME-300T tower yarder appears to be most cost-effective.