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Recent developments in on-board technology have enabled automatic collection of follow-up data on forwarder work. The objective of this study was to exploit this possibility to obtain highly representative information on time consumption of specific work elements (including overlapping crane work and driving), with one load as unit of observation, for large forwarders in final felling operations. The data used were collected by the John Deere TimberLink system as nine operators forwarded 8868 loads, in total, at sites in mid-Sweden. Load-sizes were not available. For the average and median extraction distances (219 and 174 m, respectively), , , , and effective work (PM) accounted for ca. 45, 19, 8.5, 7.5 and 14% of total forwarding time consumption, respectively. The average and median total time consumptions were 45.8 and 42.1 minutes/load, respectively. The developed models explained large proportions of the variation of time consumption for the work elements and , but minor proportions for the work elements and Based on the means, the crane was used during 74.8% of PM time, the driving speed was nonzero during 31.9% of the PM time, and occurred during 6.7% of the PM time. Time consumption per load was more strongly associated with distance than with extraction distance, indicating that the relevance of extraction distance as a main indicator of forwarding productivity should be re-considered.LoadingUnloadingDriving emptyDriving loadedOther time Driving emptyDriving loadedLoading Unloading. LoadingLoadingSimultaneous crane work and drivingLoadingLoading drive

On Nordic clearcuts, todayâs tree planting machines produce high-quality but costly regenerations. Much of this high cost is attributable to the planting machinesâ low productivity. One promising way of raising productivity is to lessen the time spent manually reloading seedlings onto the carousels of crane-mounted planting devices. Using MagMat, a carousel test-rig designed by engineering students, we studied how much faster tray-wise seedling reloading is on the Bracke Planter compared to reloading with todayâs seedling-wise-loaded carousel. The MagMat test-rig held eight Hiko cultivation trays from which seedlings were deplugged individually and dropped into the planting tube. The time study confirmed that seedling reloading was on average twice as fast with MagMat compared to todayâs seedling carousel, thereby increasing assumed planting machine productivity by 8â9% depending on the planting device used. MagMatâs cost-efficiency was analysed to be particularly reliant on its added investment cost, mechanical availability and how quickly trays can be switched automatically. Nevertheless, MagMatâs field performance illustrated the overall potential of tray-wise loading compared to piecewise seedling loading for increasing the productivity of crane-mounted planting devices. Also, deplugging proved to be a reliable method of extracting seedlings from the rigid, copper-painted Hiko cultivation trays even when performed at the excavatorâs boom-tip during mounding work. We conclude that, rather than piecewise seedling loading, tray-wise loading combined with deplugging seedlings from suitable cultivation trays is a reliable and much more time-efficient method to feed seedlings on probably any type of tree planting machine.

Forwarding has been carried out for 50 years, but much is still unknown about this work. Its complexity comes from both stand features and essential decision-making. Forwarding time consumption is influenced by e.g. log concentrations and number of assortments. Traditionally, focus has been on the total log concentration (TLC), referring to all logs at the harvesting site. However, we focused on forwarded log concentration (FLC), the load-specific log concentration which depends on the assortment distribution at harvesting site and the load-specific number of assortments. To evaluate the effects of TLC, number of assortments in a load and FLC on the loading and unloading times, a standardized field experiment was carried out. Pile and load sizes were constant, while TLC and FLC were manipulated by varying the pile distribution on the test path. For all work elements, the time consumption per m was significantly affected by the number of assortments that were loaded, but only the âdriving while loadingâ work element was also significantly influenced by TLC. However, when untangling the intercorrelation between tested factors, it was found that the time consumption for driving while loading significantly decreased as a function of FLC and was unaffected by the number of assortments in a load. That FLC influences the forwarding time consumption highlights the need to study the effects of combining various assortment proportions in a load. Such knowledge will enable analysis of the most efficient number and assortment proportions to combine in the various loads required to forward a given stand.3

Todayâs crane-mounted planting heads plant seedlings with biologically similar or better results than operational manual planting. However, the total cost of mechanized tree planting in southern Sweden must decrease at least 25% to compete economically with manual planting. Although seedlings packed in machine-specific packaging increase the productivity of planting machines by reducing seedling reloading time, they also increase logistics and investment costs. In this study, we analyzed the total cost of outplanting seedlings with an excavator-mounted Bracke Planter and seedlings packed according to four different concepts: cultivation trays, cardboard boxes, band-mounted seedlings in cardboard boxes and linked pots in container modules. The total cost per planted seedling was calculated for each packaging system as the sum of all costs from nursery to the recovery of empty packaging. The results showed that todayâs system of transporting seedlings in cultivation trays is the most cost-efficient of the four alternatives. Machine-specific seedling packaging was 16â23% costlier per planted seedling than cultivation trays when trucking distances were 100 km. Sensitivity analyses indicated that machine-specific seedling packaging increased in cost-efficiency relative to cultivation trays primarily when more planting machines were contracted, but also as planting machine fixed costs and productivity increased. Moreover, the relative cost-efficiency of band-mounted seedlings, but not seedlings in container modules, increased with increasing trucking distance. Thus, we show that investments in machine-specific seedling packaging for todayâs planting machines are justified only when the fixed costs, productivity and number of contracted planting machines increase substantially.

Stumpwood attracts renewed interest due to increased use of forest biomass for bioenergy. In Nordic countries stumps are generally uprooted with crawler excavators, which have strong cranes (ca. 400 kNm gross lift torque), but are not designed for moving in forest terrain. Their use is based on practical experience with available and tested machine types rather than thorough examinations of requirements, partly due to limited knowledge of force requirements for uprooting of stumps. Therefore, in this work mean and maximum forces required to vertically uproot stumps of Norway spruce (Picea abies) and birch (Betula spp.) were quantified together with the effects of various soil types and uprooting methods. The used excavatorâs crane-mounted uprooting device enabled comparisons between usage of solely crane force, and a method in which preparatory loosening forces were applied prior to crane force. Uprooting stumps in single pieces proved difficult; 61% split unintentionally. Force requirements were similar across tree species, increasing curve-linearly with stump diameter, and stumps uprooted in a single piece required more force than split stumps. Preparatory loosening reduced crane force requirements and, surprisingly, less force was required to uproot stumps from a mesic, till soil than from a moist, finer-textured soil. No stump required more than 60 kN crane force and functions for maximum force requirements indicate that powerful harvesters and forwarders (gross crane lifting capacity of 273 and 155 kNm, respectively) should be able to uproot all stumps with ⤠61 cm and ⤠32 cm diameter, respectively, in one piece. Larger stumps could be managed if it is acceptable that stumps are split before uprooting.

When recovering logging residues (LR) for bioenergy its density should be increased before road transport, otherwise a low proportion of the trucksâ load capacity will be used. One way this can be currently done is to compress LR into bundles that are forwarded to roadside landing. A less well-developed alternative is to forward loose LR and bundle it at landing. In the presented study, a prototype specifically developed for road-side bundling was found to produce larger, heavier bundles than bundling machinery intended for in-field use (mean length, diameter and raw bulk density 4.7 m, 0.8 m and 285 kg m, respectively, with 299â445 kg oven dry matter per bundle). The machine was also at least 30% more productive than previously described in-field bundling systems, producing 14â19 bundles per productive work hour (PWh), equivalent to 5.2â7.8 oven-dry tonnes PWh. Bundles were estimated to use 67â86% of an LR truckâs 30 tonnes load capacity, similar to proportions used when transporting loose LR. However, a continuous feeding and compressing process would probably almost double productivity, while longer bundles would enable full use of truck load capacity. With such improvements bundling at road-side could provide a viable alternative to current LR-recovering systems.â3â1

Firewood, which is mainly processed by the consumer, is still an important source of energy for heating houses in industrialised countries. Possibilities to compare the mechanizationâs impact on efficiency of firewood processing are limited, due to variations between working conditions in previous studies. Therefore, the objective was to compare time consumption for two small-scale firewood processing systems with different levels of mechanisation under identical conditions. The systems were tested on two classes of wood: one with a homogeneous and medium-sized diameter of logs and one with a mixture of small and large-diameter-logs. Differences in time consumption were analysed for correlations with physical workloads, deviations to routine operations, operator influences and operator perceptions. Twelve operators (60â79 years old) were studied and they showed large variation in time consumption. However, the within-operator time consumption patterns were consistent. In other words, operators all responded similarly to the different combinations of systems and wood classes, but at different absolute levels. The time required to process a unit volume of wood was 25â33% lower when the more highly mechanised system was used, and the time required was 13â22% lower for the homogeneous wood class. Physical work load, deviations and perceptions of the work varied between operators, but were weakly correlated with time consumption. The resultsâ implications for analyses of investments in equipment for firewood-processing for self-sufficiency purposes are discussed.

The forest sector is a significant contributor to Swedish society but requires continuous improvements in logging operations. Implementing innovations in operations is dependent on advances in other sectors, since forest machine manufacturers have only a fraction of the development capacity of, e.g., car or truck manufacturers. The aim of this study was to identify the most promising logging-machine systems, with different innovations, for implementation within ten years. The Delphi method was used to gather expert views on the importance of criteria in their decision making, their expectations regarding developments in external factors, and the most promising machine systems. Environmental and social criteria were ranked higher than economic criteria, but the rankings were relatively close. A future with greater and more stringent regulation was expected, but with scope to improve operations through technological developments such as automation and remote control. There was interest in new machine systems, but the established system dominated. Of the expected innovations, renewable energy sources were ranked highly, along with the automation of the work elements that are easiest to automate. The study provides stakeholders with a basis for decision making regarding which technologies to evaluate and test in the future. [ABSTRACT FROM AUTHOR]

Stem size has the greatest effect on harvester productivity, and stem sizes vary in a forest stand. How these within-stand variations influence harvester productivity is normally not considered in studies or predictions of productivity. This study suggests reasons as to why the current production and/or application of productivity models are prone to bias from stem size variations in a stand, irrespective of whether models were developed from tree-based or stand-based studies. Moreover, it also provides empirical data on the stand stem size variation's influence on stand-based modeling of harvester productivity. Data from 11 harvesters in 347 final fellings and four harvesters in 80 thinnings were used. The mean productivity was 26.7 and 11.0 m3/PMh5 in final felling and thinning, respectively, and the mean stem size explained most of the observed variation. The productivity in final felling decreased with increased levels of stand stem size variation, as well as with increases in the proportion of broadleaf trees in the stand. For thinnings, productivity increased with increases in the proportion of pine trees in the stand, but there was no significant effect of stand stem size variation or other tested factors. The results show that stand stem size variation is a relevant factor to consider when modeling and predicting harvester productivity. [ABSTRACT FROM AUTHOR]

As various methods for precision inventories, including light detection and ranging (LiDAR), are becoming increasingly common in forestry, planning at the individual-tree level is becoming more viable. In this study, we present a method for finding the optimal thinning times for individual trees from an economic perspective. The method utilizes a forest growth model based on individual trees that has been fitted to Norway spruce (Picea abies (L.) Karst.) stands in northern Sweden. We find that the optimal management strategy is to thin from above (i.e., harvesting trees that are larger than average). We compare our optimal strategy with a conventional management strategy and find that the optimal strategy results in approximately 20% higher land expectation value. Furthermore, we find that for the optimal strategy, increasing the discount rate will reduce the final harvest age and increase the basal area reduction. Decreasing the cost to initiate a thinning (e.g., machinery-related transportation costs) increases the number of thinnings and delays the first thinning. Key words: forest management, optimization, precision forestry, simulation, thinning. La planification a l'echelle de l'arbre devient de plus en plus viable a mesure qu'augmente le recours a diverses methodes d'inventaire de precision en foresterie, telles que le lidar (<>). Dans cette etude, nous presentons une methode visant a determiner les periodes optimales d'application d'une eclaircie pour les arbres individuels d'un point de vue economique. La methode utilise un modele de croissance forestiere a l'echelle de l'arbre qui a ete ajuste a des peuplements d'epicea commun (Picea abies (L.) Karst.) du nord de la Suede. Nous avons trouve que la strategie d'amenagement optimale consiste a eclaircir par le haut, c'est-a-dire a recolter des arbres plus gros que la moyenne. Nous avons compare notre strategie optimale a une strategie d'amenagement conventionnelle et avons constate qu'elle produit une augmentation de la valeur actualisee des terres d'environ 20 %. De plus, lorsque la strategie optimale est associee a une augmentation du taux d'actualisation, l'age de la recolte finale diminue et le prelevement en surface terriere augmente. Une diminution des couts associes a l'eclaircie (p. ex., les couts de transport mecanise) augmente le nombre d'eclaircies et retarde l'application de la premiere eclaircie. Mots-cles: amenagement forestier, optimisation, foresterie de precision, simulation, eclaircie., Introduction Given the ecological and economic importance of forests, it is not surprising that much effort has been invested in developing and improving forestry practices. Increasingly common use of remote [...]

This article presents a study on the world's first unmanned machine designed for autonomous forestry operations. In response to the challenges associated with traditional forestry operations, we developed a platform equipped with essential hardware components necessary for performing autonomous forwarding tasks. Through the use of computer vision, autonomous navigation, and manipulator control algorithms, the machine is able to pick up logs from the ground and manoeuvre through a range of forest terrains without the need for human intervention. Our initial results demonstrate the potential for safe and efficient autonomous extraction of logs in the cut‐to‐length harvesting process. We achieved a high level of accuracy in our computer vision system, and our autonomous navigation system proved to be highly efficient. This research represents a significant milestone in the field of autonomous outdoor robotics, with far‐reaching implications for the future of forestry operations. By reducing the need for human labor, autonomous machines have the potential to increase productivity and reduce labor costs, while also minimizing the environmental impact of timber harvesting. The success of our study highlights the potential for further development and optimization of autonomous machines in the forestry industry. [ABSTRACT FROM AUTHOR]

Ground-based mechanized forestry requires the traversal of terrain by heavy machines. The routes that they take are often called 'machine trails' and are created by removing trees from the trail and placing the logs outside it. Designing an optimal machine trail network is a complex locational problem that requires understanding how forestry machines can operate on the terrain, as well as the trade-offs between various economic and ecological aspects. Machine trail designs are currently created manually based on intuitive decisions about the importance, correlations, and effects of many potentially conflicting aspects. Badly designed machine trail networks could result in costly operations and adverse environmental impacts. Therefore, this study was conducted to develop a holistic optimization framework for machine trail network design. Key economic and ecological objectives involved in designing machine trail networks for mechanized cut-to-length operations are presented, along with strategies for simultaneously addressing multiple objectives while accounting for the physical capabilities of forestry machines, the impact of slope, and the operating costs. Ways of quantitatively formulating and combining these different aspects are demonstrated, together with examples showing how the optimal network design changes in response to various inputs. Key words: mathematical modeling, forest engineering, machine trail network, environmental impact, logistics. L'exploitation forestiere mecanisee necessite que la machinerie lourde se deplace sur le terrain. Les chemins qu'elle emprunte sont souvent appeles des sentiers de machines et sont crees en enlevant les arbres et en placant les billes sur le cote du sentier. La conception d'un reseau optimal de sentiers de machines est un probleme complexe de localisation qui exige de comprendre de quelle facon la machinerie forestiere peut operer sur le terrain, ainsi que les compromis entre divers aspects economiques et ecologiques. La conception des sentiers de machines est actuellement realisee manuellement sur la base de decisions intuitives au sujet de l'importance, de la correlation et des effets de plusieurs aspects potentiellement antagonistes. Les sentiers de machines mal concus pourraient engendrer des operations couteuses et avoir des impacts nefastes sur l'environnement. Par consequent, cette etude a ete realisee dans le but de developper un cadre d'optimisation holistique pour la conception des reseaux de sentiers de machines. Les objectifs ecologiques et economiques cles retenus dans la conception de reseaux de sentiers de machines pour des operations mecanisees de recolte par bois tronconnes sont presentes, ainsi que les strategies pour repondre simultanement a plusieurs objectifs tout en tenant compte des capacites physiques de la machinerie forestiere, de l'impact de la pente et des couts d'operation. Des facons de combiner et de formuler quantitativement ces differents aspects sont illustrees avec des exemples montrant comment la conception du reseau optimal change en reaction a differents intrants. [Traduit par la Redaction] Mots-cles : modelisation mathematique, genie forestier, reseau de sentiers de machines, impact environnemental, logistique., 1. Introduction In ground-based forestry, large volumes of timber are extracted from forest to roadside using heavy vehicles. When conducting 'close-to-nature' forestry, the machines should ideally be able to operate [...]

The extraction of timber is expensive, energy intensive, and potentially damaging to the forest soil. Machine development aims to mitigate risks for environmental impact and decrease energy consumption while maintaining or increasing cost efficiency. The development of rubber-tracked forwarders has gained renewed interest, not least due to climate change leading to unreliable weather in combination with low tolerance for soil damage. The increased cost of rubber tracks compared to wheels is believed to be compensated by higher driving speed enabled by semi-active suspension. Thus, the aim of this study was to theoretically investigate how the productivity and cost efficiency of rubber-tracked forwarders are affected by variations in driving speed and machine costs. The calculations were made with fixed stand parameters, to evaluate performance in well-defined working conditions, and with parameters from 2500 final felling stands in central Sweden, to evaluate performance in varied working conditions. Scenarios were compared to a baseline corresponding to mid-sized wheeled forwarders. The results show higher productivity with the increased driving speed enabled by rubber tracks and suspension at all extraction distances, with larger differences at long extraction distances. Assuming a 15% higher machine price for the rubber-tracked forwarder and a variable cost increase proportional to speed increase, extraction costs break even with the baseline at 400 m and 700 m extraction distance for moderate and fast driving speed, respectively. Furthermore, a rubber-tracked forwarder is likely to enable access to a larger part of the harvest area during longer seasons. For the studied set of stands, the year-round accessible volumes are estimated to increase from 9% to 92% with a rubber-tracked forwarder. With rubber tracks instead of wheels, good accessibility has the potential to be combined with low soil impact and cost efficiency in a favourable way for both industry and ecosystem. [ABSTRACT FROM AUTHOR]

Most forest operations are complex problems that require the weights of relevant criteria – representing trade-offs between various economic, ecological, and social aspects of the problem – to be defined. Usually this is done by using multicriteria weighting method(s) in a group (participatory) context in order to include different opinions and to minimize risk of poor individual judgments. Furthermore, in group decision-making, the weights of decision makers (DMs) must be defined. However, no consensus exists on the best way to determine related weights assigned to DMs. For that purpose, we propose the consistency-based group decision-making framework (CGDF), which uses the expertise of a DM to weight the responses of the DM when deriving an overall group decision. The novel part of CGDF is the inter-weights consistency method (ICM) for evaluating the expertise of a DM based on the consistency of the weights the DM assigns to different criteria using different multicriteria weighting methods. We demonstrate the utility of ICM and CGDF by applying them to a decision-making problem from Swedish forest operations – defining weights of criteria relevant for designing the machine-trail network for driving in the forest terrain. [ABSTRACT FROM AUTHOR]

There is a need to decrease the costs of cut-to-length operations. The harwarder, a one-machine system with the potential to reduce the costs, has been compared to the two-machine system (TMS) at the stand and regional levels but not at the national level, which is important as basis for decision to implement. The objective was therefore to analyze its potential on a large scale in Swedish final fellings. It was evaluated using two modeling approaches in conjunction with data representing around 30% of Sweden's yearly final fellings from five forestry organizations. The analyses revealed that total costs could be reduced by around 3% if up to 50% of the total volume was logged using harwarders rather than the TMS. This would require the introduction of up to 250 harwarders into machine fleets that currently use only the TMS. The two modeling approaches gave similar results. It was concluded that the harwarder may need to demonstrate greater potential to justify a full-scale implementation in Swedish forestry, but the machine could be improved through technological development, especially through automation. [ABSTRACT FROM AUTHOR]

There are many factors to consider when deciding which technologies to use in forest operations and how to plan their use. One important factor is the overall cost when choosing between the established two-machine system (TMS) with a harvester and a forwarder, and a one-machine system with a harwarder in final fellings. Such considerations can be done with different model approaches, all of which have their strengths and weaknesses. The aim of this study was to analyze and compare the TMS and harwarder potential using a Detailed Optimization (DO) approach and an Aggregated Heuristic (AH) approach. The main differences are the aggregation of seasons, including machine system teams, and spatial considerations. The analyses were done for one full year of final fellings for a large forest company's region in central Sweden, containing information necessary for calculating costs for logging, relocation between stands and traveling between the operator's home bases and the stands. The approaches were tested for two scenarios; when only TMS were available, and when both TMS and harwarders were available. The main results were that the approaches coincided well in both potential to decrease total costs when harwarders where available, and distribution of TMS and harwarders. There were some differences in the results, which can be explained by differences in thecalculation approach. It was concluded that the DO approach is more suitable when detailed analyses are prioritized, and the AH approach is more suitable when a more approximate analysis will suffice or the available resources for making the analysis are more limited. [ABSTRACT FROM AUTHOR]

In many parts of the world, contractors account for the main share of harvesting work. Harvesting is characterized by innate complexity and volatility, and this can affect contractors' workflow and ultimately their profitability. Thus, there is certainly a need for flexibility in harvesting service provision and procedures, but our current knowledge about contractors' workflow variations are limited. This study investigates workflow variations in harvesting services by comparing monthly variations between contractors' workload in terms of harvested volumes and the time spent on operations. The data originates from 77 machines belonging to contractors and their harvesting of 6.6 million m3 of roundwood in Sweden during a two-year period. The results indicate differences between contractors' workflow variations which can be attributed to the number of machines, machine sizes, and the workload in harvested volume and hours. These findings are relevant for guiding both the customer and contractor in this business relationship, and they could also serve as a basis for further research on the need for flexibility to effectively increase and decrease volume production in harvesting services. [ABSTRACT FROM AUTHOR]

In conventional mechanized cut-to-length systems, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs directly into the load spaces of transporting machines as they are cut. Such integrated loading could result in cost reductions, shorter lead times from stump to landing, and lower fuel consumption. However, it might also create waiting times for the machines involved, whereas multifunctional machines are likely to be expensive. Thus, it is important to analyze whether or not the advantages of any changes outweigh the disadvantages. The conventional system was compared with four potential systems, including two with autonomous forwarders, using discrete-event simulation with stochastic elements in which harvests of more than 1000 final felling stands (containing in total 1.6 million [m.sup.3]) were simulated 35 times per system. The results indicate that harwarders have substantial potential (less expensive on ≥80% of the volume and fuel consumption decreased by ≥18%) and may become competitive if key innovations are developed. Systems with cooperating machines have considerably less potential, limited to very specific stand conditions. The results conform with expected difficulties in integrating processing and transporting machines' work in variable environments. Resume: Dans les procedes mecanises conventionnels de recolte par bois tronconne, une abatteuse-faconneuse coupe et tronconne les arbres en billes qui sont entreposees au sol jusqu'a ce qu'un porteur les ramasse et les transporte jusqu'a une jetee. Une amelioration qui a ete proposee consiste a placer les billes directement dans l'espace de chargement des porteurs a mesure qu'elles sont coupees. Un tel chargement integre pourrait reduire les couts, le delai entre la souche et la jetee ainsi que la consommation de carburant. Cependant, cela peut egalement engendrer des periodes d'attente pour la machinerie concernee alors que les machines multifonctionnelles risquent d'etre onereuses. Par consequent, il est important de determiner si les avantages des changements l'emportent sur les desavantages ou non. Le procede conventionnel a ete compare a quatre procedes potentiels, incluant deux procedes avec porteurs autonomes, en utilisant la simulation d'evenements discrets avec des elements stochastiques au moyen de laquelle la coupe definitive de plus de 1 000 peuplements (contenant au total 1,6 million de [m.sup.3]) a ete simulee 35 fois avec chaque procede. Les resultats indiquent que les machines multifonctionnelles ont beaucoup de potentiel (plus economiques pour [greater than or equal to]80 % du volume et consommation de carburant reduite de ≥18 %) et peuvent devenir competitives si des innovations cles sont developpees. Les procedes qui impliquent la cooperation de differentes machines ont beaucoup moins de potentiel et sont limites a des conditions de peuplement tres specifiques. Les resultats correspondent aux difficultes anticipees par l'integration des machines qui effectuent la transformation et le transport dans des environnements variables. [Traduit par la Redaction], Introduction During the last 50 years, forest operations have been subject to many steps of mechanization. The forces driving mechanization have included labor shortages, an aspiration to perform forestry operations [...]

The mechanization of roundwood harvesting in Sweden has historically cut costs rapidly. However, machinery and work methods have conceptually stayed the same since the introduction of the single-grip harvester. Current trends indicate that the next major wave of development will be based on automation, and that teleoperation is a step in this direction. This study aims to evaluate the economic potential of semi-automated tele-extraction compared to standard forwarding within the Nordic CTL two-machine harvesting system. The initial scenario examined autonomous terrain transportation with teleoperation during loading and unloading. A Discrete Event Simulation was implemented in the AnyLogic software. Input data included 1100 Swedish harvest sites, with in total 1.6 million m3 and extraction distances from 20 to 1500 m. Scenarios with different numbers of teleoperators for a fleet of ten forwarders were tested. The optimum number of operators was seven per ten forwarders, resulting in a potential extraction cost reduction of 7% compared to standard forwarding. Extraction distances further than 500 m enabled use of five or six teleoperators, resulting in potential cost reductions of up to 15%. The highest potential cost reductions were linked to increased time used for autonomous driving, increasing the teleoperator availability for other machines. The simulation model provides a framework for further evaluation of new scenarios of automation and teleoperation of forwarders. [ABSTRACT FROM AUTHOR]

The extensive outsourcing of forest harvesting operations means that the operational performance of contractors has an immense impact on the forest industry supply chain. This study describes perceived drivers and obstacles for strong performance in harvesting service based on semi-structured interviews with four production supervisors and eight contractors. The analysis of interview data revealed a wide array of factors considered to drive or hinder the performance. The factors were categorized into five types: Capability, Incentives, Commitment, Involvement and External factors. Factors concerning Capability, especially resources and competence, were most frequently considered by production supervisors as both drivers and hinders. The contractors considered most commonly Incentives to affect performance, especially motivation and strategy, as drivers and the economy as hinder. Both parties considered lack of resources as hinder to performance. For competence, relationship and collaboration interface, on the other hand, the two parties had different views on whether they acted as drivers or hinders. The knowledge presented in this paper is of interest to researchers or practitioners who wishes to understand the complexities underlying successful harvesting service performance. The insights can contribute to the reshaping of business practices to better target and leverage the mechanisms that most strongly affect performance. [ABSTRACT FROM AUTHOR]

Despite the large biomass potential, current management practices for roadside verges (ditch backslopes,foreslopes and bottoms, possible parking lots and other lateral land) consist of regularly cutting the vegetation manually with motorized brush saws or flail mowers and leaving it to rot in situ. Regular vegetation clearing is crucial for safety reasons and to maintain road functionality. This study considered the cost-efficiency of a mechanized harvesting system, using a harvester and a forwarder (as an alternative to current clearing practices), to maintain the verges of a forest road in northern Sweden. Cutting a 2.5-m wide swath on each verge removed between 32 and 112 dry t ha−1 (16–56 dry t km−1 of road) of biomass. Analyses showed that the use of forest machinery to cut and extract biomass from roadside verges can be cost-competitive compared with motor-manual clearing when the average tree height is above 7 m (~26-year-old trees), and profitable for average heights above 8 m (~29-year-old trees). As the overgrown biomass has to be cleared anyway, a mechanized harvest could partially or fully offset maintenance costs. When setting cutting intervals, a trade-off needs to be made between larger biomass production and maintaining a clear and safe road. Future research needs to investigate how size, density of vegetation and width of the cleared swath affects the long-term quality and safety of roads. [ABSTRACT FROM AUTHOR]

Modern forest harvesters automatically collect large amounts of standardized work-related data. Statistical machine learning methods enable detailed analyses of large databases from wood harvesting operations. In the present study, gradient boosted machine (GBM), support vector machine (SVM) and ordinary least square (OLS) regression were implemented and compared in predicting the productivity of cut-to-length (CTL) harvesting based on operational monitoring files generated by the harvesters' on-board computers. The data consisted of 1,381 observations from 27 operators and 19 single-grip harvesters. Each tested method detected the mean stem volume as the most significant factor affecting productivity. Depending on the modeling approach, 33–59% of variation was due to the operators. The best GBM model was able to predict the productivity with 90.2% R2, whereas OLS and the SVM machine reached R2-values of 89.3% and 87% R2, respectively. OLS regression still proved to be an effective method for predicting productivity of CTL harvesting with a limited number of observations and variables, but more powerful GBM and SVM show great potential as the amount of data increases along with the development of various big data applications. [ABSTRACT FROM AUTHOR]

Operators of mobile machines within forestry work long hours in seated postures while being exposed to whole-body vibration (WBV) that is associated with pain in the lower back and neck. Still, little is known about the contribution from postural loads. In this study postural loads and shock-type WBV exposure on drivers operating a forwarder during terrain-like conditions was measured and quantified using inertial measurement units (IMUs). Five male drivers drove a forwarder repeatedly over standardized steel obstacles using a predefined speed and posture followed by driving over natural obstacles along a terrain course using a self-selected speed and posture. IMUs were affixed along the spine, on the back of the head of the driver and on the seat to detect orientation, velocity, and acceleration. The result shows that the methodology for measuring WBV and postural load with IMUs is feasible. Postural loads, expressed as range of motions (ROMs), when driving over a single standardized obstacle at a speed of 3.3 km/h were up to 21° in the neck segments. Increasing vehicle speed and size of obstacles increased postural loads. The terrain course resulted in higher ROMs in all body segments compared to a standardized obstacle, a difference in sideway seat acceleration but no differences regarding angular velocities of the head. Mechanical shocks at the seat were prevalent but the action limit value was exceeded only for one driver. Postural loads remained small during all conditions indicating that the spine can remain stable during exposure to shock-type WBV of this nature. [ABSTRACT FROM AUTHOR]

Quad bikes are light-weight vehicles which are used for transportation of personnel, equipment, and material in forestry operations such as planning, logging, planting, and fire-fighting. With increased quad bike usage, serious injuries have become an increasing concern. The most common forms of severe incidents occur when a quad bike loses stability, causing injuries as it rolls over the rider trapped beneath. The risk of injuries during a rollover incident can be decreased by equipping the vehicle with rollover protection systems (ROPS), but since ROPS tend to decrease the stability of quad bikes, their use can be a trade-off between the risk of overturning and the outcome of any such incident. In this study, we examine the effects of approach angle, trailer load, ROPS and different hardware configurations on a quad bike's static stability. We found that approach angle and trailer configurations influenced the vehicle's stability, although the effect was difficult to quantify in a static environment. Furthermore, the quad bike's stability was negatively influenced by equipping it with a heavy (44 kg) ROPS. It reduced the static stability by an average of 5.1°, while a light (14.7 kg) prototype ROPS only reduced the vehicle's static stability by an average of 1.0°. The negative impact a ROPS has on a quad bike's lateral stability could be effectively counteracted by increasing the quad bike's track width. Increasing track width by less than 2% (20 mm) compensated for any negative impact that the light prototype ROPS had on the quad bike's lateral stability. [ABSTRACT FROM AUTHOR]

Performing work for extended periods of time while using the lowest amount of resources is an important aspect for productivity in many industries. In forestry, the productivity of a forwarder is seen as the volume of material it can extract to a roadside landing in a certain amount of time, where the process of loading and unloading logs represents a large part of the work. During this process, the esnergy consumed by the machine is directly related to the speed of the crane. Thus, increasing productivity implies increasing the operating velocity of cranes. But according to current design of forestry cranes, this conversely leads to an undesired increase in consumption of resources (e.g. fuel). A second method is to alter the machine's design, such as rotating the log bunk. This article considers both methods through a simulation-based comparison aiming to evaluate the energy consumption of two crane-bunk systems when loading. The first simulation system considers a forestry crane with a fixed log bunk (forwarder-like crane). The second simulation system takes into account a forestry crane and a rotating log bunk (harwarder-like crane). The analysis presented considers the fundamental mathematics required to analyze the dynamics of forestry cranes and the principles required to plan energy-optimal motions. The simulation results show that energy savings of 43% to 61% can be obtained by determining energy-optimal motions and using a harwarder-like crane architecture. [ABSTRACT FROM AUTHOR]

Farm tractor + trailers play a key role in wood transportation after forests are logged. Despite of the fact that a forwarder is a forestry vehicle that carries felled logs for shorter distances off the ground, tractors are still used in some forest areas of the world, such as the Hyrcanian forest in northern Iran. This study was conducted to investigate the possibility of using both the light forwarder and forestry trailer instead of a farm tractor + trailer in wood transportation. The optimal machine option for wood transportation is determined using goal programming model in the study area. In this paper, multi-objective goals (such as economic, operational, environmental and ergonomic) were considered. The results showed that considering only the economic goal, the contractor could save up to 44% in costs by purchasing and replacing a forestry trailer with a 2-wheel trailer attached to the farm tractor. In addition, considering various goals, a light forwarder could be selected as the optimal machine. Currently, the most important objectives of all forest contractors are to establish economic goals and reduce wood transportation costs. Since other goals, such as environmental and ergonomic, are also important; it is suggested that multi-objective approaches should use for planning. [ABSTRACT FROM AUTHOR]

Size and spatial distribution of trees are important for forest stand growth, but the extent to which it matters in thinning operations, in terms of wood production and stand economy, has rarely been documented. Here we investigate how the choice of spatial evenness and tree-size distribution of residual trees impacts wood production and stand economy. A spatially explicit individual-based growth model was used, in conjunction with empirical cost functions for harvesting and forwarding, to calculate net production and net present value for different thinning operations in Norway spruce stands in Northern Sweden. The in silico thinning operations were defined by three variables: (1) spatial evenness after thinning, (2) tree size preference for harvesting, and (3) basal area reduction. We found that thinning that increases spatial evenness increases net production and net present value by around 2.0%, compared to the worst case. When changing the spatial evenness in conjunction with size preference we could observe an improvement of the net production and net present value up to 8.0%. The magnitude of impact differed greatly between the stands (from 1.7% to 8.0%) and was highest in the stand with the lowest stem density. [ABSTRACT FROM AUTHOR]

Competition for woody biomass between material and energy uses is expected to further increase in the future, due to the limited availability of forest resources and increasing demand of wood for material and bioenergy. Currently, methodological approaches for modeling wood production and delivery costs from forest to industrial gates are missing. This study combines forest engineering, geographically explicit information, environmental constraints and economics in a bottom-up approach to assess cost–supply curves. The estimates are based on a multitude of wood supply systems that were assigned according to geographically explicit forestry characteristics. For each harvesting and transportation system, efficiencies were modeled according to harvesting sites and main delivery hubs. The cost–supply curves for roundwood and logging residues as estimates for current time and for the future (2030) show that there are large regional differences in the potential to increase extraction in the EU28. In most EU Member States, the costs of logging residues extraction increase exponentially already for low levels of mobilization, while extraction of roundwood can be increased to a larger extent within reasonable costs (30–40 $/m3). The large differences between countries in their harvest potential highlight the importance of spatially explicit analyses. [ABSTRACT FROM AUTHOR]

Accurate vehicle localization in forest environments is still an unresolved problem. Global navigation satellite systems (GNSS) have well known limitations in dense forest, and have to be combined with for instance laser based SLAM algorithms to provide satisfying accuracy. Such algorithms typically require accurate detection of trees, and estimation of tree center locations in laser data. Both these operations depend on accurate estimations of tree trunk diameter. Diameter estimations are important also for several other forestry automation and remote sensing applications. This paper evaluates several existing algorithms for diameter estimation using 2D laser scanner data. Enhanced algorithms, compensating for beam width and using multiple scans, were also developed and evaluated. The best existing algorithms overestimated tree trunk diameter by ca. 40%. Our enhanced algorithms, compensating for laser beam width, reduced this error to less than 12%. [ABSTRACT FROM AUTHOR]

In the mechanized cut-to-length system, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs in the load space of the transporting machine as they are cut. Two approaches for this integration of work tasks are available: technical, using a single machine (a harwarder), and organizational, using a harvester to place cut logs directly into the bunk of a waiting forwarder. Here, the theoretical potential of the two approaches is evaluated using a developed methodological framework. In static modeling, the same type of work took equally long times for variants of both approaches. The results indicate that harwarders (first conceived more than 50 years ago) have substantial theoretical potential and may finally become competitive if key innovations are developed. Conversely, there was very limited theoretical potential for organizational integration, using either a manned or unmanned harvester, because the interacting machines are not affected by the same environmental factors. Hence their interdependency generates waiting time under most stand conditions, and the reduced costs of an unmanned harvester are insufficient to compensate for the increased time consumption. [ABSTRACT FROM AUTHOR]