Yarding Distance Research Articles

A Simulation Study of Noise Exposure in Sledge-Based Cable Yarding Operations

Ensuring the safety of forestry workers is a key challenge, particularly when working with partly mechanized harvesting systems. Cable yarding is typically used in steep terrain timber harvesting. For long-distance extraction, one of the few alternatives is to use sledge yarders, but these machines may expose workers to high doses of noise. The goal of this study was to model haulers’ exposure to noise in sledge-based cable yarding operations, based on a simulation approach that considered variable factors such as the yarding distance, lateral yarding distance, and average skyline height. Taken into consideration were 165 scenarios developed by examining the variation in yarding distance (500 to 1500 m, with a step of 100 m), lateral yarding distance (10 to 50 m, with a step of 10 m), and average skyline height above the ground (10, 15, and 20 m). The simulations assumed an 8-h working day with a break of 1 h. The models and statistics published by other studies were used to calculate the time consumption and number of work cycles completed within a working day. These data were used to compute the equivalent exposure to noise (LAeq) for each scenario, as well as for those work elements that were likely to expose the haulers to noise the most. The presented findings indicated that (i) the exposure to noise was higher than 100 dB(A), irrespective of variation in the considered factors; (ii) the trend in exposure was characterized by polynomials in relation to the extraction distance, and the magnitude of exposure was consistently affected by variation in the considered factors; and (iii) without hearing protection, the empty and loaded turns exposed workers to noise over the permissible limits. These findings strongly suggest the use of hearing protection when working in close proximity to sledge-based cable yarding operations. The methods proposed in this study in the form of simulation may help benchmark other forest operations.

Productivity Analysis of Mid-Size Cable Yarding Operation based on UAV-captured Video Sequences

Cable yarding is one of the most preferred timber extraction methods in steep and mountainous terrain conditions. In recent years in Turkiye, mid-size cable yarders have begun to be used frequently in steep forest areas where intensive forestry is carried out. In order to make more effective use of cable yarders and achieve maximum productivity, timber extraction operations must be planned most appropriately and implemented in the field accordingly. The productivity of mechanized equipment used in harvesting operations is mainly determined by using time study analysis. In traditional methods, time measurements are carried out by observing the work stages with time recording devices (stopwatches) in the area where the machine operates. Since timber extraction by using a cable yarder occur in steep and rugged terrain conditions, difficulties may be encountered in applying time analysis in the field. In this study, it was aimed to obtain high-resolution digital video images of the activities of cable yarding operation with an Unmanned Aerial Vehicle (UAV) and to calculate productivity through time study analysis on these images. For the study, the Tajfun MOZ 500 GR model mid-size cable yarder was evaluated during a timber extraction operation in Köyceğiz Forest Enterprise Chief (FEC), located in Muğla City, Turkiye. Besides, statistical analysis was performed to estimate the effects of factors such as average product length, product diameter, lateral yarding distance, number of pieces, and total product volume per turn on the productivity of the cable yarder. The results indicated that UAV video images can be an effective alternative method to conduct time study analysis and productivity estimations. It was found that the productivity of the mid-size cable yarder was 11.76 m3/hour. During the operation, the pulling mainline to the product and choker setting were the most time-consuming work stages, followed by the time-loaded carriage reaching the landing. The statistical analysis indicated a significant relationship (p<0.001) between product length, product diameter, total volume and productivity of the cable yarder. The results showed that there was a negative relationship between lateral yarding distance and productivity. The regression model regarding the productivity of the cable yarder and the independent variables was also significant.

Evaluating Productivity of Small-Scale Cable Yarding System Integrated with a Portable Winch

Small-scale forestry operations, which are used in non-industrial and site specific forestry, provide alternative logging methods suitable for precision forestry approach. In this study, a small-scale cable yarding system integrated with a portable winch was considered as alternative timber extraction method compared to a standard tower yarder. It was aimed to evaluate productivity of this yarding method, which was implemented during commercial harvesting activities performed in a 10.74 ha black pine stand located in Bursa province of Turkey. The main factors (i.e. slope, yarding distance, lateral pulling distance, log volume, log length), significantly affecting the productivity, were evaluated based on two slope classes (34–50% and 50–70%) and two yarding distances (100 m and 200 m). The results indicated that the average productivity was 0.95 m3/PMH and 0.90 m3/SMH. It was revealed that the productivity of the small-scale cable yarding decreased as the ground slope and the yarding distance increased. Statistical analysis indicated that there was a significant (p<0.001) relationship between productivity and log volume and length in four applications. On the other hand, it was found that there was a significant (p<0.05) relationship between productivity and lateral pulling distance in only the first application (34–50% slope; 100 m yarding distance). Considering the volume classes of the logs, it was determined that the productivity increased from the low volume class to the high volume class.

A Prototype for Automated Delimitation of Work Cycles from Machine Sensor Data in Cable Yarding Operations

The demand for increased efficiency in timber harvesting has traditionally been met by continuous technical improvements in machines and an increase in mechanisation. The use of active and passive sensors on machines enables improvements in aspects such as operational efficiency, fuel consumption and worker safety. Timber harvesting machine manufacturers have used these technologies to improve the maintenance and control of their machines, to select and optimise harvesting techniques and fuel consumption. To a more limited extent, it has also been used to evaluate the time taken to complete tasks. The systematic use of machine sensor data, in a central database or cloud solution is a more recent trend.Machine data is recorded over long periods of time and at high resolution. This data therefore has considerable potential for scientific investigations. For mechanised timber harvesting operations, this could include a better understanding of the interaction between productivity and operational parameters, which first of all requires an efficient determination of cycle time.This study was the first to automatically delimitate tower yarder cycle times from machine sensor data. In addition to machine sensor data, cycle times were collected through a traditional manual time and motion study, and cycle times from both studies were compared to a reference cycle time determined from video footage of the yarder in operation.Based on three days of detailed time study, the total cycle time in the classic manual time (–1.3%) and in the machine sensor data (–1.2%) was only slightly shorter than in the reference study, and the average cycle time did not differ significantly (classic manual time study: –0.08±0.94 min, p=0.997; machine sensor data study: –0.08±0.26 min, p=0.997). However, the accuracy of the machine sensor approach (RMSE=0.92) was more than three times higher than that of the classic manual time study (RMSE=0.27).With the integration of sensors on forestry machines now being commonplace, this study shows that machine sensor data can be reliably interpreted for time study purposes such as machine or system optimisation. This eliminates the need for manual time study, which can be both cumbersome and dependent on the experience of the observer, and allows long term data sets to be obtained and analysed with comparatively little effort. However, a truly automated time study needs to be supplemented with automated determination of and linkage to other operational parameters, such as yarding and lateral yarding distance or load volume.

Evaluation of Different Modes for Yarding Windthrown Timber with a Double-Hitch Carriage

Yarding whole trees is the most efficient way of extracting timber in steep terrain and allows reaping the combined benefits of mechanization and biomass recovery. In downhill yarding, however, whole-tree extraction is associated with a greater risk of loosening rocks or debris by the incoming loads as they bounce around along the extraction corridor. That may also cause damage to the cables and anchors by corresponding shock loads, ultimately endangering the yarder and its crew. To avoid these risks, »double-hitch carriages« can be employed. They combine a conventional motorized dropline carriage with a secondary carriage (»trailer«), equipped with a further, independent dropline winch. Thus, loads can be attached at two points and transported fully suspended above the ground in a horizontal position.Operation of these carriages may not be limited to the »horizontal« mode: the main carriage could also be operated without trailer (»single« mode), or separate loads may be attached to the two droplines (»double« mode), but their impact on the efficiency and economy of yarding operations is yet unknown. Therefore, the present study investigated how these modes affect the productivity and cost of downhill whole tree yarding. To this end, a classic time and motion study was conducted during a salvage logging operation in Northern Italy under a strictly controlled experimental design.Average productivity (18.2±7.2 to 24.5±15.4 m³ PSH0-1 merchantable volume per productive system hour excluding delays) and extraction cost (18 to 20 Euro m-³) did not differ significantly between treatments, while load composition and time consumption by task did. More (2.2±0.5) pieces per load were yarded under the »double«, than under the »single« (1.4±0.5) and »horizontal« (1.1±0.3) treatments. Inhaul speed (3.1±0.6 m s-1) was significantly higher under the »horizontal« treatment, which compensated for increased loading time derived from attaching the load at least at one point outside the corridor. Unloading took significantly longer under the »double« treatment, as loads had to be dropped successively due to the confined conditions on the landing. Though slowest (2.5±0.9 m s-1) during inhaul, the »single« treatment exhibited none of the other treatments disadvantages and larger loads could be accumulated due to partial suspension. From an economic viewpoint, the »horizontal« mode may only be warranted over yarding distances substantially beyond average. On shorter ones, it must be justified by other reasons, such as minimizing product contamination, soil disturbance or excessive strain to the skyline when the terrain profile impedes sufficient ground clearance.

New technological solutions for waterlogged forests by cable yarding

The article proposes new technological techniques for clear cutting in swampy areas using standing skylines, new construction of yarder and the technology of its operation. As a result of the research on using the Larix 3T-500 cable yarder in winter and summer, the operational negative peculiarities of tower yarder in waterlogged forests were identified. Analysing data on experimental comparative time studies, some measures to reduce the negative effect of the identified features on yarding, felling, lateral yarding were worked out. General recommendations for work performance in swampy logging areas were developed. Based on the initial data for each bundle (yarding distance, lateral yarding distance, average volume of the bundle, etc.) the calculation in the MathCad program was performed and a regression dependence of the yarder performance was obtained. Obtained numerical data on comparative time studies of the working cycle operations were summarized in bar charts, taking into account the loss of time on operations.

Salvage cable yarding operations productivity of pinewood nematode infected Pinus trees in South Korea

ABSTRACT Salvage logging of nematode-infested pinewoods could increase in South Korea, because of the risk of pest spread in response to climate change. No previous studies have precisely determined how to extrapolate information regarding cable extraction productivity and cost in salvage logging operations to steep terrains in South Korea. Therefore, in this study, the performance of a semi-mechanized system was observed at two different harvesting sites located in areas affected by the pinewood nematode (Bursaphelenchus xylophilus). The following were the specific aims of this study: (1) to evaluate HAM200 yarder productivity and cost in four different conditions (50 and 100 m yarding distances in uphill and downhill directions), and (2) to identify significant independent variables related to productivity. The HAM200 productivity values varied considerably and ranged from 1.95 to 2.52 m3/productive machine-hour (costs 43.29–55.81 US $/m3, respectively). Overall, productivity for trees damaged by uphill yarding was 20% higher compared to downhill yarding while productivity was not significantly different. Yarding direction, lateral distance, volume per cycle, and interaction of volume per cycle with lateral distance significantly affected the productivity. Further, our regression model, uphill yarding should be favorable from 35 to 100 m yarding distances. The findings of this study would enable better planning and decision-making regarding salvage logging, thereby allowing improved production of damaged trees.

Evaluation of Salvage Logging Productivity and Costs in the Sensitive Forests of Bulgaria

Steep terrain harvesting can only be implemented by a limited set of operational alternatives; therefore, it is important to be efficient in such conditions, in order to avoid incurring high costs. Harvesting abiotically-disturbed forests (salvage harvests caused by wet snow), which is becoming common these days, can significantly impact the operational efficiency of extraction operations. This study was implemented in order to evaluate the performance of truck-mounted uphill cable yarding operations in salvage logging deployed in coniferous stands. A time study was used to estimate the productivity and yarding costs, and predictive models were developed in order to relate the time consumption and productivity to the relevant operational factors, including the degree of wood damage. The average operational conditions were characterized by an extraction distance of 101 m and a lateral yarding distance of 18 m, resulting in a productivity rate of 20.1 m3 h−1. In response to different kind of delays, the productivity rate decreased to 12.8 m3 h−1. Under the prevailing conditions, lateral yarding accounted for 32% of the gross work cycle time, and for 50% of the delay-free work cycle time of the machine. Decreasing the lateral yarding distance and increasing the payload volume to the maximum capacity of the machine would eventually lead to a yarding productivity of close to 30 m3 per SMH (scheduled machine hour). The calculation of the gross costs of uphill yarding showed that the labor costs (35.7%) were slightly higher than the fixed costs (32.9%), and twice as high compared to the variable costs (17.7%). The remote control of the carriage, mechanical slack-pulling mechanisms, and radio-controlled chokers are just some of the improvements that would have led to increments in operational efficiency.

Productivity, fuel consumption and cost in whole tree cable yarding: conventional diesel carriage versus electrical energy-recuperating carriage

ABSTRACT Cable yarding is an inherently expensive extraction technology, but the mainstay for mountain forest management. Fuel cost represents a considerable share of total harvesting costs. Energy-recuperating, electrical slack-pulling carriages (EC), which recuperate energy during lateral yarding and store it as electrical energy in super-capacitors for powering slack-pulling during the subsequent yarding cycle have emerged only recently. Fuel consumption of cable yarding is expected to be lower when ECs are employed compared to working with conventional, diesel engine-powered slack-pulling drive (DC) carriages. To determine if reality matched expectations, a time and motion study was conductedduring which fuel consumption was extracted from the engine control systems using custom-made dataloggers for an uphill whole tree yarding operation in Austria. Average productivity was 21.9 m3 per productive system hour excluding delays (m3 PSH0 −1) at 0.89 m3 average tree volume and 58.4 m average yarding distance. Productivity was modeled as a function of average tree volume, yarding distance and lateral yarding distance. Average fuel consumption was 1.27 ± 0.97 l m−3 (DC) and 0.88 ± 0.56 l m−3 (EC). In the DC treatment, the carriage engine accounted for 9% of the total fuel consumption. Modeling revealed that fuel consumption depended on average tree volume, yarding distance, lateral yarding distance and carriage type as originally postulated. The latter effect interacted with that of average tree volume and EC’s advantage in fuel consumption was limited by a break-even average tree volume. In conclusion, the EC has the potential to improve profit margins in small-tree operations through lower fuel consumption.

Performance and cost of downhill cable yarding operations in a group shelterwood system

ABSTRACTCable yarding operations are conventionally used in steep terrain harvesting, but their share in operations varies widely, tending to be low in many regions. This study evaluated the time consumption, productivity and cost of downhill sledge-yarding operations in group shelterwood extractions deployed in steep terrain beech forests. Relevant operational variables (yarding distance, lateral yarding distance and slope) were selected as predictors to model the time consumption based on a number of 558 work cycles. For an extraction distance of 326 m, a lateral yarding distance of 43 m and a payload of 1.87 m3 per turn, the yarding cycle time was estimated to about 12.5 min. Notable as share in the yarding cycle time were the choking (28%), lateral-in (19%), lateral-out (16%) and unchoking (13%), with the second and the third work elements being significantly affected by very high lateral yarding distances. Estimated productivity and efficiency rates were of 8.80 m3 h−1 and 0.11 h m−3, respectively. Extraction costs were estimated at 7.4 € m−3, in which the operator costs contributed the most (4.3 € m−3). Given the low fossil energy inputs, increased environmental performance due to suspended extraction of the logs, and the acceptable productivity and cost, this system could be extended in low-accessibility, steep-terrain harvesting.

Rendimiento de un sistema de cable en relación a la intensidad del régimen silvícola

La máquina más común en México para arrime de trocería es la motogrúa. Este trabajo describe sus partes, funciones y sistema de trabajo. Usando datos de tiempos y movimientos de 334 ciclos de trabajo en condiciones de monte de coníferas en tercer paso de corta en Michoacán, México, se ajustaron ecuaciones de regresión para el tiempo de trabajo por fase del ciclo en función de la carga, arbolado residual, distancia de arrime y variables topográficas. El conjunto de estas funciones permite estimar el desempeño de la motogrúa tanto para propósitos de eficiencia industrial, como para eficacia en la aplicación de variados tratamientos silvícolas. Los resultados confirman la alta productividad de esta forma de arrime, lo mismo que sus deficiencias en cuanto al considerable daño al rodal residual y la necesidad de una cantidad enorme de brechas de saca que mantengan la distancia media de arrime a menos de 70 m, a pesar de tener un alcance máximo potencial de 400 m.

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.

An economic model for integrated roading, yarding, and hauling operations on two alternative harvest unit landings

This paper presents an economic model for the optimization of a vertically integrated timber harvesting operation. The operations of road construction, timber yarding, and log truck hauling are collectively optimized. The harvest unit has two centralized landings that are to be accessed by truck road from a single existing road takeoff point. The harvest unit is located on level, unvarying terrain with uniformly distributed log turns. Formulas for the optimal yarding boundary between the landings, areas yarded to each landing, and the average yarding distances are derived. These formulas are then used in the bilevel optimization of a vertically integrated timber harvesting operation. Numerical examples are presented and discussed.

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.

Optimal road spacing of cable yarding using a tower yarder in Southern Austria

Cable yarding systems are widely used in mountainous forests of Austria. The goal of this paper is to determine optimal road spacing (ORS) of yarding operations by tower yarder in Styria to help logging planners minimize logging costs. A total of 591 working cycles were used to develop the multiple regression model using stepwise method to predict yarding time per cycle. The production and cost in whole tree uphill yarding were 6.70 m3/PSH and 27.60 Euro/m3, respectively. The roading, yarding and installation cost per cubic meter were computed for different yarding distances and graphed as a function of road spacing. The minimum total cost and ORS were 42.88 Euro/m3 and 261 m, respectively for one-way yarding. For two-way yarding, the minimum estimated total cost, ORS and optimal road density would be 38.48 Euro/m3, 373 m and 26.8 m/ha, respectively. The results showed increasing harvested volume decreases ORS and that increased roading cost increases ORS. The load volume has a significant effect on ORS.

Evaluating Economic and Wildlife Habitat Considerations for Snag Retention Policies in Burned Landscapes

Abstract Wildfires have become more frequent and intense in recent years in the western United States. Previous studies have investigated the potential environmental and economic impacts of active management in burned forest landscapes. No previously published study, however, has considered wildlife requirements for snags while planning salvage logging operations in postburned landscapes. We examined the potential impacts of 19 snag retention strategies using cable-based yarding systems over a 3-year time period since burn. The strategies were based on current research recommendations, operational needs, and state and federal policies. Potential impacts on two cavity-nesting bird habitats and the feasibility of each strategy were examined. We found that most snag retention strategies generated net revenues per unit volume of merchantable wood greater than $70/m3 immediately after a burn and $60/m3 3 years after a burn. Those strategies that focused snag retention on smaller-diameter stems had the highest net revenue values and higher productivity rates. We also found that the strategy that removed all merchantable snags did not produce the highest revenue. In general, decreased yarding distance and a smaller yarding system (e.g., shovel loader) resulted in greater net revenue per unit volume with increased time since burn. The salvage strategy that provided the most favorable habitat for the two cavity-nesting birds left all snags standing in the half of the salvage unit farthest away from the yarder. Our findings indicate that it is possible to provide adequate cavity-nesting bird habitat and generate net revenue during fire salvage operations.

Evaluating the Salvage Value of Fire-Killed Timber by Helicopter—Effects of Yarding Distance and Time Since Fire

Abstract Recently, large areas of federal lands in the western United States have been subject to wildfire. Concerns about hastening restoration, soil disturbance, and road building have prompted consideration of helicopter logging. Normal planning procedures on federal lands are not sensitive to the rapid decline in the recoverable economic value of fire-killed timber. The economic value of fire-killed timber is dependent on logging costs and time since tree death. A model is developed to calculate value of fire-killed timber as a function of time since death and yarding distance using helicopters as the preferred logging method. Applications of the method to tactical planning are discussed.

Optimization of Road Spacing for Log Length Shovel Logging on Gentle Terrain

Shovel logging has become a popular logging system in the western United States due to its high productivity. Its low ground pressure and single pass, often on a matt of limbs result in little ground disturbance. Despite this increasing popularity, there have been few operational studies of shovel logging. This paper describes the optimal road spacing problem for shovel logging using a serpentine pattern on gentle terrain. A mathematical model for shovel logging is presented for two cases (1) to minimize the sum of shovel yarding costs plus road costs from the landowner’s point of view and(2) to maximize profits from the point of view of a logging contractor. For the operating conditions assumed, the optimal shovel yarding distance is four swings when shovel yarding plus roads costs are minimized and three swings when logging contractor profit is maximized. For the example data, the model results demonstrate the flexibility of shovel logging in that there is little difference between total road construction plus skidding cost from the optimal number of swings to as many as six swings. Sensitivity analysis was performed on road cost and volume per ha and support the stability of the solution with the minimum logging cost occurring at four swings with just a small difference for as many as six swings over a range of road construction and volume removals.

Measuring the interactive behavior of yarding distances with geometric attributes of irregular-shaped harvest units

Measuring the interactive behavior of yarding distances with geometric attributes of irregular-shaped harvest units