Cable Skidders Research Articles

Productivity of TIMBERJACK 240A and LKT 81T Skidders at Selective Cutting and Longer Distances

The extraction of wood from forests is a difficult, risky, expensive, and time-consuming operation, especially in mountainous areas and selective forests. In the forestry of Bosnia and Herzegovina (BIH), winching and skidding of wood assortments is most often done with cable skidders. They are the most applicable because they can handle hilly, mountainous and inaccessible terrain in the compartments that are most common in local forestry. In addition, selective and group-selective forest management systems are dominant, where the manoeuvring of any type of machinery is strictly limited to the skid trails and skid roads. It is a matter of legal and sub-legal regulations and environmental standards. Striving for higher productivity and economy of skidding is ultimately one of the objectives of forest management. Different Timberjack and LKT models of skidders are widely used in BIH. The study was conducted in the area of two public forest enterprises, in compartments 32 (Forest management unit "Vrbanja") and 99 (Forest management unit ““Lješljanica-Maglajska”) with similar stand and relief conditions. The research objects were two skidders, which are used very often in the forestry of BIH, LKT 81T and Timberjack 240A. Skidder LKT 81T was used in compartment 32, where 29 cycles were recorded, during which 212 logs were skidded. Total volume of skidded wood was 159.98 m3 with average volume of 5.52 m3·load-1. Timberjack 240A was used in compartment 99, where 84 cycles were recorded, with 398 logs. Total skidded wood with Timberjack 240A was 657.34 m3, with average volume of 7.83 m3·load-1. Relative share of work operations showed that loaded and unloaded drive had the largest share, onsie In case of LKT 81T loaded drive was 31% and unloaded drive 25%, while for Timberjack 240A skidder loaded drive accounted for 44% and unloaded drive for 37% of productive work time. Average skidding distance for loaded drive was 1080.34 m for LKT 81T and 727.98 for Timberjack 240A. Unloaded drive, manoeuvring drive and loaded drive showed dependence on corresponding distances. With the increase of the distance and volume of the load, the time required for skidding per unit of product increases. In comparable range (up to 900 m), for the same load size, Timberjack 240A achieved lower standard time, i.e., higher productivity than LKT 81T. Using a skidder at longer distances significantly reduces productivity and increases costs. However, planners often decide in such cases to use a cable skidder for wood skidding, knowing that the costs will be higher, which is again a better option than not harvesting parts of the compartment.

Forest Operations Using a Combi–Forwarder in Deciduous Forests

In the last decade, technological innovation in the forest operations sector has allowed levels of mechanization alternative to agricultural tractors and animal logging. These machines are used to load logs from skid roads and move logs to the next pile, until the load space is fully loaded. Fortunately, in recent years the development of new technological progresses in forestry mechanization created an alternative operation on ground-based system with the use of a combi-forwarder for wood forwarding. These innovative machines have the advantage that only one machine can perform logs bunching and primary transport. Infact, pull stems by the winch from the stump to the road, after they have been cross-cutted by chainsaws, it loads by the forwarder’s crane the logs and transports them to the landing, where they are unloaded with the crane in piles.The aim of the present study was to analyse the operational time consumption, to estimate the productivity of the combi–forwarder with a built-in single-drum winch in beech stands evaluating the forwarding and winching distances, log’s volume transported per turn by the machine, as well as the extracting costs. The study was conducted in low-intensity shelterwood cuttings in beech forest, located in Western Balkan Mountains, Bulgaria.The mean productivity of the combi–forwarder was 7.09 m3 PMH− 1 and 6.11 m3 SMH− 1 close to that of the cable skidders and forwarders in similar conditions. The net costs for the studied combi–forwarder were calculated of 25.33 € per productive machine hour and 4.13 € per m3. The variable costs (70%) have a leading role, followed by labour costs (22%) and fixed costs (8%). The use of a combi-forwarders facilitates chainsaw operators, as some of the operations are carried out at the roadside in better working conditions: flat terrain and support of the crosscutting phase. The results from the study are useful to introduce and to integrate the combi–forwarders with shelterwood systems and to achieve economic and environmental efficiency of timber harvesting in deciduous forests.

Productivity analysis and costs of wheel cable skidder during salvage logging in European beech stand

Salvage logging is increasing in Central Europe because of the growth of severe meteorological events, and timber harvesting in these conditions is challenging in terms of both productivity performances and safety of the operations. In recent years, with the increase of natural calamities, several researchers studied machinery productivity performances regarding salvage logging carried out by ground-based systems. In fact, a common post-disturbance management approach is salvage logging which consists of the widespread removal of damaged trees. In this research, system productivity and the cost of salvage logging are analysed in European beech stands affected by wet snow. The accretion of heavy wet snow poses the greatest risk to forests in the Northern Hemisphere. This type of snow attaches more effectively to tree crowns and branches when temperatures are close to freezing at the time of precipitation. As a result, trees may break or bend and may be uprooted when the soil is unfrozen. This study has been implemented to evaluate the productivity and cost-effectiveness of extraction in salvage logging deployed with a skidder in beech stands affected by two different types of wet snow damage. The results show that the productivity of the four-wheel-drive cable skidder, despite operating in salvage cutting with a removal intensity of 10%, is 14.73 m3·SMH–1, similar to skidder performances in ‘ordinary’ cuttings. Skidder’s productive time was 86% of the scheduled time, whereas the delays were due to organisational reasons, mechanical delays, and adverse weather conditions. The mean travel speed of the cable skidder obtained in this study is close to the results obtained from other studies on similar machines. The costs per unit are lower than effective cost consumptions for the other cable skidders and agricultural tractors, adapted for skidding operated in hardwood salvage logging. Therefore, under the given conditions, the operation of the fourwheel-drive cable skidder is viable from a silvicultural, technical, and economic point of view in the salvage operation logging.

A Preliminary Validation and Assessment of a GIS Approach Related to Precision Forest Harvesting in Central Italy

There has been a growing awareness of the need for sustainable forest management among forest engineers during the last decades. The selection of the best harvesting system for logging operations plays a fundamental role in this effort. Nowadays, in the decision-making process, forest engineers rely on their own experience, and it is to be expected that their evaluation of the level of appropriateness may be biased. There may be a potential solution to this problem in the implementation of AHP (Analytic Hierarchy Process) in the GIS (Geographic Information System) environment. The application of AHP gives objective information and thus reduces the level of bias in deciding which logging harvest system is best to use. The aim of this study was to evaluate the reliability of a GIS-AHP approach applied to the development of the harvesting plan of a public forest estate in Central Italy. Three extraction methods were considered: forwarder, cable skidder, and all-terrain cable yarder. Thus, the GIS-AHP model was run by relying on the basic data attainable from the local forest management plan and then on detailed information provided by field data collected from 10 harvested blocks. Among these, in three blocks, the logging harvest method was changed from forwarder to cable skidder. Statistically significant differences were found between the suitability values obtained from the forest management plan and those retrieved from the field surveys for the forwarder and cable skidders but not for all-terrain cable yarders.

Analysis of the time efficiency of skidding technology based on the skidders

Abstract The time efficiency and principles of ergonomics related to timber skidding are based on the time consumption per work cycle as well as on the time consumption per individual work operations. Regarding the demands on the environmental requirements and ever increasing cost of work, it is necessary to objectively evaluate the inevitable time consumption required for timber skidding using all technologies. The paper summarised the results of time studies for skidder technologies. The time study compares the time consumption and productivity of cable skidders and cable-grapple skidders, with the main focus on developing time prediction models. The main aim of the study was to objectify the skidder time consumption and establish the impact of production factors on the time consumption of partial work operations of skidders. Within the time study 231 work cycles were measured, and 53 snapshots of work day with using methods continual time study. The overall time consumption of the work cycle and gross production rate of the monitored cable and cable-grapple skidders is affected by the following production factors: the skidding distance, volume of skidded logs and number of skidded logs. The impact of individual production factors on the overall time consumption of the work cycle is different for each group of skidders. Non-operation times of the skidder operators’ shifts represent 24.6% with the highest part taken by the technical operation of the work place. The mean gross production rate of the monitored skidders varied from 33.3 to 6.91 m3 h−1.

Timber transportation planning using bees algorithm

Timber transportation planning is among the costliest activities in forest operation. Traditionally, the goal of timber transportation planning adopted to determine feasible way to extract high timber volume from the stump site to the final destination. However, modern transportation problems are not driven by the productivity of timber itself, but also by the efficiency of forest operation. This efficiency considerations and requirements introduce a new technique in timber extraction called log fisher as a complement to common technique, cable skidder. Nevertheless, side constraints within timber transportation planning may arise when two timber extraction techniques applied, complicates to and from several problems more extensive and more complex. While cable skidders affixed only on gentle slopes, log fishers possibly applicable regardless of slope conditions. Proper evaluation required to justify decisions since the use of these two techniques in the right places will result in efficient timber transportation planning. In the present study, a new problem-solving approach using Bees Algorithm (BA) was developed. BA can provide transportation planner with a large and complex transportation planning problem solving while complying with the forest road guidelines as required by the Forestry Department of Peninsular Malaysia. Herein, timber extraction technique is considered the least-cost in the main objective function for an efficient timber transportation planning and limitation of machinery to extract timber as constraints. Preliminary results show that this problem solving is promising for timber transportation planning problems with side constraints. A description of the algorithm development and its search process presented within this study.

Modelling and comparing timber winching performance in windthrow and uniform selective cuttings for two Romanian skidders

Cable skidders are one of the most used means for logging. In overall skidding operations, winching operations mark themselves out by consuming an important amount of time, which, depending on the work conditions can reach up to 43 % of the total skidding time. A better understanding of those conditions that may act as significant influence factors when estimating time consumption is needed as a prerequisite for better work organization. Based on an extensive time study, this paper demonstrates that along with influence factors that were already identified as being significant (especially winching distance), other influence factors, such as log volume, work pattern, felling area conditions and intervention type, slope, and winching direction, may prove significant in predicting time consumption for the main work elements of winching operations, as well as for a winching cycle. All the variables mentioned presented a great significance (p < 0.05) for a winching replication, and taken apart, they presented great significances for certain work elements. Distance was the most significant independent variable for all the realized time prediction models, slope and winching direction became relevant especially in the case of manual pulling of the cable, whereas intervention type and work patterns made the difference when performances were evaluated. The amount of data within data pools may have a great importance when trying to emphasize the relevance of different variables, as demonstrated by this paper.

Modelling of wander ratios, travel speeds and productivity of cable and grapple skidders in softwood sawtimber operations in South Africa

The objective of this study was to develop predictive models for cable and grapple skidder wander ratios, travel speeds (loaded and unloaded), and productivity in softwood roundwood sawtimber harvesting operations. For field data collection, the study utilised on-board computing systems supported by manual time study. Four-hundred and twenty-seven extraction cycles over varying terrain and tree sizes were studied for 13 sites in the Western, Southern and Eastern Cape, and KwaZulu-Natal. Machine make and model as well as gross power rating were studied. Due to insignificance across skidder types and configurations, the objective of creating a predictive model for skidder wander ratio was not met. The overall mean wander ratio for all skidders and terrain studied was 1.12:1. This value was used in the models subsequently developed. No differences were found for unloaded and loaded travel speeds between individual skidder types and speeds were found to be 7.3 km h−1 and 5.5 km h−1, respectively. In terms of productivity, when based on field-measured data, there were differences between skidder types with cable skidders achieving 43.9 m3 per productive machine hour (PMH) and grapples skidders 123.9 m3 PMH−1. The study, however, found that both cable and grapple skidders were only hauling approximately 50% of their capacity and for that reason multiple regression models to predict potential production at full payload capacity were developed for the two skidder configurations. Multiple regression was also used to develop prediction models for travel speeds loaded and unloaded. The study met its objectives for driving speeds and productivity, and the developed models will be used in a subsequent network analysis to provide solutions to optimise the softwood sawtimber supply chain. The study also found that the human element had an impact on the factors studied and that good training, planning, implementation and operational control are imperative to ensure supply (or value) chain goals are met.

On-board computing in forest machinery as a tool to improve skidding operations in South African softwood sawtimber operations

On-board computing (OBC) systems in South African timber-harvesting operations are currently limited because of the lack of local expertise and experience. In this study three trials were conducted, monitoring three skidder extraction operations at three sites in South African softwood sawtimber operations. Both cable and grapple skidders were equipped with a MultiDAT data collection device. For all trials, parallel manual time studies were conducted. The results from the time-studies were then used as the basis for evaluation of the accuracy of the information gathered by the OBCs. The results demonstrated the usefulness of OBC devices. This paper reports the results of the application of various tools to support these assessments, considering different levels of complexity, different detail of the results and different fields of application (business uses and research purpose). With regards to the estimation of the machine utilisation rate, it was highlighted that the use of the vibration sensor with additional input from the machine operator in order to define the reason for stopping offered the best solution with an error ranging from -0.74% to +5.54%. This tool can be used in long-term monitoring to identify the possible under-utilisation of a machine and consequently to establish a working system that provides greater productivity. For the evaluation of machine utilisation, the simple analysis of the GPS track-log also provided good results with an error ranging from 4.29% to -4.25%, but it required time-consuming post-operation processing of the raw data in order to correctly interpret. The use of GPS data to perform work studies in general worked reasonably well, the main problem being again that, at certain stages, the process was not easily automated and tended to require time-consuming post-operation data manipulation. However, because of the amount of information derived from data processing, it presents a useful research tool. The introduction of simple OBCs in South Africa is possible, but does require organisational changes and adaptations from both machine operators, who need to be trained to understand and manage the specific user interface and data transmission, and from management responsible for data storage, collation and analysis, and subsequently the implementation of results in improving forest operations.

Ergonomic evaluation and comparison of wood harvesting systems in Northwest Russia

A comparison of 14 currently applicable wood harvesting systems was assessed with respect to ergonomic point of view. For this purpose, the research method, based on the Hodges–Lehmann rule and the integrated work-severity rate of single machinery, was developed for ergonomic evaluation of cut-to-length, tree-length and full-tree harvesting systems. Altogether, about 130 different parameters of 36 units of equipment that impact on the ergonomics and work conditions were measured and estimated in interviews undertaken directly at forestry harvesting workplaces in 15 logging companies in the Republic of Karelia, Northwest Russia. Then the results were compared to the effective norms, and the degree of compliance with the stipulated values was determined. The estimates obtained for the degree of compliance were combined. This permits a direct comparison of the workload on forestry harvesting workers such as operators, lumberjacks and choker setters. In many respects, the current ergonomic standard is standard, except for the operators of cable skidders, chainsaws and choker settings. Visibility and work postures were considered to be the most critical features influencing the operator's performance. Problems still exist, despite the extensive development of cabs. The best working conditions in terms of harvesting systems were provided by “harvester + forwarder” in cut-to-length harvesting, and “feller–buncher + grapple skidder” in full-tree harvesting. The motor-manual tree-length harvesting performed with cable skidders showed the worst results in terms of ergonomics.

Investigating of Residual Tree Damage During Ground-Based Skidding

The study aims assessed the damages caused by skidding compared with the damages reported in other logging and skidding studies. Skidding had been conducted using cable skidders. After finishing the skidding operations, a field survey was done to collect data of all residual trees (species, DBH, height) and of tree wounds (size class, location and intensity of damage). Two types of damages were recorded: scarring and root damage. Results show that approximately 80% of the residual trees were damaged and that 52% of the residual trees have been affected by at least one new damage.

Macroinvertebrate community responses to selection logging in riparian and upland areas of headwater catchments in a northern hardwood forest

Aquatic insect communities were examined in 2 streams at different selection logging intensities in headwater catchments of a northern hardwood forest. Insect communities of these streams were compared to those of a nearby reference stream (no harvesting) over a 2-y pre- and 3- y post-logging period. The experimental catchments were logged by a mechanical harvester and cable skidders, one at a low-intensity (29% basal area removal) and the other at a moderate-intensity (42% basal area removal) harvesting rate. There were no riparian reserves or buffer zones, but logging was conducted in compliance with a riparian code of practice (3-m setback from stream edges) and other best management practices. Changes in community structure, community metrics, or relative abun- dance of discriminatory taxa attributable to logging impacts were not detected at the low-intensity site. Some deviations from reference and pre-logging trends in community structure, multivariate dispersion, and population levels of discriminatory taxa were detected at the moderate-intensity site after the logging. These deviations were mainly driven by small, but usually significant, increases in abundance of 5 gatherer taxa. The increases in abundance of gatherer taxa appeared to be a response to a significant increase (;2.53) in streambed deposition of fine particulate organic material at that site. However, the shifts in community structure and changes in abundance of these taxa at the moderate-intensity site were not larger than some natural changes in abundance among other taxa at the reference site over the 5-y study. The increases in abundance of some taxa at the moderate- intensity site may indicate a logging impact, but the changes were small and there were no indications of reciprocal declines among other taxa. It appears that selection logging at up to 42% basal area removal in compliance with the riparian code of practice and other good management practices largely mitigated harmful alterations to stream habitat and insect communities in these northern hardwood forest catchments.

Costs of forestry best management practices in the south: A review

In response to federal and state clean water laws, forestry best management practices (BMPs) have been developed and implemented to prevent nonpoint source water pollution. Ellefson and Miles (1985) found that estimated BMP costs in the Midwest could amount to more than half of the net returns on national forest timber sales. Henly et al. (1988) found that government costs to implement forest practice rules ranged from as little as $100,000 per year in Idaho and Nevada to more than $4 million annually in California. A review of studies in the South indicates that estimated BMP costs have increased over time. Lickwar et al. (1992) estimated Southeast average costs of $12.45 per acre, $2.34 per MBF, or 2.87% of gross stumpage values based on 1987 BMPs and prices. Woodman and Cubbage (1994) estimated Georgia average BMP costs of $24.33 per acre or $3.02 per MBF for forest industry lands and $41.65 per acre or $5.39 per MBF for NIPF lands. For Virginia, Shaffer et al. (1998) estimated median BMP costs of $18.90 per acre. These moderate cost increases could be attributed to a higher level of standards in the revision of each state BMP guidelines manual, as well as moderate price inflation. BMPs such as better road construction, water bars, culverts, and broad-based dips have been most expensive so far. To date streamside zones have not been very expensive because the rules allow most of the valuable residual tees to be harvested as long as heavy equipment does not operate near the streams. However, this limitation may become much more difficult and costly – as indicated by Kluender et al. (2000) – as fewer chainsaw fellers and cable skidders are available. Stricter BMPs, such as those already adopted to implement forest certification standards in the South or those used to protect salmon habitat in the West, could prompt more expensive southern BMPs for landowners and state agencies in the future.

Hitching optimal payloads increases skidder productivity

SYNOPSIS The study of seven articulated wheeled cable skidders at five different locations revealed that the optimism skidder pay load is not skidded. The average results of three similar Timberjack 380C skidders that formed part of tile study are discussed. The optimum payload of a skidder, whether a cable skidder or a grapple skidder, is the most important element determining its optimal use or productivity for a given stand of trees and therefore the cost of the extracted timber per cubic metre. Several methods of determining the optimum payload are discussed.

Forest damage caused by selection logging of mahogany ( Swietenia macrophylla) in northern Belize

We assessed the damage caused by selection logging of mahogany in a tropical forest in northern Belize and compared it with damage reported in other Neotropical logging and disturbance studies. We mapped skid roads and tree felling sites, and assessed soil compaction, loss of canopy cover, damage to saplings and trees, seedling survival and seedling height growth. Logging had been conducted using hand crews with chain saws and cable skidders. Logging directly affected 11.9 ha (12.9%) of the 92.3 ha logging area. Canopy cover decreased the most at logging gaps, and soils were most compacted on skid roads. Soil compaction was much greater on roads where more than one tree had been skidded. For the whole logged area, canopy cover declined 2% and compacted soils covered 3.8% of the area. Seedling height growth was unaffected by soil compaction, but seedling survival was less on compacted sites. About 50% of the trees and about 15% of the saplings were damaged in gaps and along skid roads. However, only 4.8% of the trees and 1.9% of the saplings were damaged for the logged area as a whole. The most common kinds of damage included scraped bark, snapped tops, and run-over stems. Although this logging operation had relatively low impacts compared with other logging operations in the Neotropics, it may not be silviculturally sustainable because its disturbance may be insufficient to promote adequate mahogany regeneration.

Évolution de la régénération après la coupe de peuplements récoltés selon différents procédés d'exploitation

Between 1982 and 1984, 289 sample plots were established on cutovers distributed across the mixed and the boreal forest zones of Québec. Regeneration surveys before and after clearcutting were used to determine the proportion of regeneration destroyed by four different harvesting systems. Moreover, information on the evolution of the regeneration over the medium term was gathered from surveys realized five and ten years following logging. For all stands combined, harvesting resulted in a reduction of 25 to 40% of the stocking of the regeneration. The lowest decrease in stocking was produced by a feller-forwarder that was more efficient to protect regeneration shorter than 50 cm as compared to harvesting systems using cable skidders. Differences between harvesting systems were no longer apparent after the first five-year-period following logging because establishment of new seedlings was observed in most of the sampled cutovers. The ability of balsam fir to establish under a canopy generally caused an increase of its proportion in the new stands as compared to the original stands. The proportion of hardwood species also tended to increase in comparison to the original stand in such a way that some conifer stands would evolve toward mixed stands if no change in stand composition occurred after the first ten-year period following logging. Natural regeneration of jack pine stands after harvesting seems difficult to obtain since these stands have scarce advance regeneration that is partially destroyed during logging operations. Plantation, fill plantation or seeding could be applied in these stands but harvesting methods providing protection for regeneration should be used in the other stands in order to protect advance regeneration and particularly tall individuals. Key words: clearcutting, advance regeneration, harvesting system, cable skidders, feller-forwarder

Évolution quinquennale de la régénération protégée lors de récoltes par abattage manuel dans des sapinières

In 1985, an experiment was undertaken in the Gaspé peninsula, in Québec, in different stand types to assess the feasibility of preserving advance growth by changing logging methods. This article deals with manual felling combined with wheeled cable skidders in balsam fir stands. Regeneration was assessed before, immediately after, and 3 and 5 years after logging in five 2-ha pairs of blocks, in order to compare the effect of traditional harvesting (control) and a method using directional felling and spaced skidding trails (preserved).The use of directional felling and spaced skidding trails resulted in a decreased loss of advance growth. Five years after logging, this loss in softwood stocking for the preserved blocks was still lower in each of the five pairs; the difference averaged 25%. Moreover, the regeneration height in the preserved blocks was slightly greater, which seems to indicate a lower level of invasion by brush and herbaceous vegetation after logging as a result of this method.

Modeling the Cost and Profitability of Timber Harvesting with Cable Skidders

Abstract Logging costs and profitability are affected by many variables. Computer simulation based on detailed production studies and an accounting-based cost analysis was used to investigate the relative importance of tree size and species group on logging costs and profits. Tree size had the greatest affect on skidding costs. Species group was found to be important only in felling. Marginal tree size and margins for profit and risk were computed for seven timber sales. Marginal tree size ranged from 12+ to 13+ in. Volume in submarginal trees ranged from 16.3 to 44.8% of the total volume. Margins earned by a hypothetical contractor were found to be low. The findings and methodology can be used by researchers and operations managers for analysis and planning of harvesting activities. The procedures provide a means for establishing merchantability limits for individual harvests based on characteristics of the stand, logging system, and harvest layout. They can also be used to establish equitable contract rates. North. J. Appl. For. 4:87-92, June 1987.

C-A-R-T-S: Capacity Analysis of Rubber-Tired Skidders

ABSTRACT AFORTRAN computer program was developed to model the stability, traction, and production characteristics of four-wheel drive, articulated-frame, rubber-tired cable skidders. The model is heavily dependent on the equations developed by Wismer and Luth (1972). Relative production rates can be estimated as a function of skidder design, tire size, trail slope, soil cone index, and load characteristics.

Production Rate of Rubber-Tired, Cable Skidders in Southern Forests

Production Rate of Rubber-Tired, Cable Skidders in Southern Forests