Fully mechanized timber harvesting systems are well established in forest operations worldwide. In cut-to-length (CTL) systems, forwarders are used for extracting logs from the stand. The productivity of a forwarder is related to site- and stand-specific characteristics, technical parameters, organizational aspects, and the individual skills of the operator. The operator’s performance during “loading” considerably affects forwarder productivity, since this element occupies nearly 50% of forwarding cycle time in CTL operations. When positioning the forwarder for loading, different loading angles and loading distances arise. Additionally, different log orientation angles in relation to the machine operating trail can be observed. Therefore, an in-depth analysis of loading conditions was conducted. The goal of this pilot case study was to explore the potential impact of different loading angles and distances, and log orientation angles, on time consumption per loading cycle in order to derive indications for more efficient work practices. Therefore, controlled loading sequences were tested on a physical Rottne-F10-based forwarder simulator with an experienced forest machine operator. Three loading angles (45°, 90° and 135° azimuthal to the machine axis) with five loading distances (3, 4, 5, 6 and 7 m), and three log orientation angles (45°, 90°, 135°), resulted in a total of 45 settings, which were tested in 10 repetitions each. The time required for a loading cycle was captured in a time study, applying the snap-back method. Results showed that all three tested variables had a significant influence on time consumption per loading cycle. Loading at an angle of 135°, and from a close (3 m) or far distance (7 m) led to especially increased cycle times. Loading from 4 to 6 m distance could be detected as an optimal loading range. Additionally, log orientation angles of 45° and 90° led to increased loading efficiency. Even if the validity of the results may be limited due to different conditions and influencing factors in field forwarding operations, these data can contribute to a better understanding of the loading element and, in particular, to productivity determining factors of forwarder work.
In order to compare the vibration and noise exposure of STIHL’s battery-powered MSA 220 C and the combustion driven MS 201 C, a professional operator was monitored during a pre-commercial thinning operation in a twenty-year-old hardwood stand. The vibration levels were measured with a tri-axial accelerometer on the front and rear handle of both the chainsaws, and assigned to five different work elements using a video documentation. Additionally, noise levels were recorded in one-minute intervals, with a dosemeter worn by the operator. The results show that battery-powered chainsaws, when compared to combustion-driven chainsaws, can reduce the daily vibration exposure by more than 45% and the noise dose by about 78.4%, during pre-commercial thinning tasks. Replacing combustion-driven chainsaws with battery-powered ones is therefore generally recommended, to reduce occupational health risks for operators, in this respect. However, the daily vibration exposure of about 2.42 m/s2, caused by the battery-powered chainsaw on the front handle, is still very close to the daily exposure action value set by the EU directives for health and safety requirements. The daily noise exposure of 89.18 dB(A) even exceeds the upper exposure action value. Consequently, a further reduction in the vibration exposure during work is desirable. With respect to noise exposure, additional measures must be implemented for conformity with the current safety standards, making the use of hearing protectors mandatory for electric chainsaws, too.
Digitalization and its associated technology are shaping the world economy and society. Data collection, data exchange, and connection throughout the wood supply chain have become increasingly important. There exist many technologies for the implementation of Industry 4.0 applications in forestry. For example, the integration of harvester production data throughout the wood supply chain seems to have strong optimization potential but it is faced with several challenges due to the high number of stakeholders involved. Therefore, the objective of this article is to analyze the legal, social, and economic conditions surrounding the integration of harvester production data integration in Germany. For analysis of the legal and economic conditions, a narrative literature analysis was performed with special consideration of the relevant German and European legal references. For determination of the social conditions, a qualitative content analysis of 27 expert interviews was performed. Results showed that legal ownership of harvester production data cannot be clearly defined in Germany, but there exist several protection rights against misuse, which can define an ownership-similar data sovereignty. Furthermore, harvester data use can be restricted in the case where personal data are traceable, based on European data protection law. From a social perspective, the stakeholders interviewed in the study had different opinions on data ownership. Stakeholders require specific criteria on the data (interfaces) and other factors for the acceptance of new structures to allow successful harvester data integration. From an economic perspective, harvester production data are tradeable through varying transaction forms but, generally, there is no accepted and valid formula in existence for calculating the value or price of harvester data. Therefore, the authors advise discussing these issues with key stakeholders to negotiate and agree on data ownership and use in order to find a suitable solution to realize optimization potentials in the German wood supply chain.
Variance in productivity of fully mechanized timber harvesting under comparable stand and terrain conditions requires the investigation of the influence of work practices of machine operators. Work practices can vary among operators and may result in a wide range of productivity. Therefore, it is of great interest to identify positive and negative work practices of forest machine operators to improve forest work. For the qualitative analysis of work practices, 15 forest machine operator instructors were interviewed in Norway, Sweden, and Germany in semi-structured interviews. Additionally, a literature review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. The interviews brought up detailed positive work practices and showed negative examples of machine handling, specifically related to boom operation. The literature review retrieved 2482 articles of which 16 were examined in more detail. The review showed that work practice characteristics were only sparsely covered, however, still overlapped with the work practice recommendations from the operator instructor interviews. Further, the literature search unveiled a scientific knowledge gap related to the quantification of applied work practices. Generally, positive work practices can include using optimal working ranges from 4–6 m, frequent machine repositioning, a matched fit of operator skill and crane speed, and an assortment pile size that matches the maximum grapple loads. Training is recommended to focus on crane control in terms of movement precision and work range adherence whereby the speed-accuracy trade-off should be improved to meet productivity requirements and increase efficiency in forest machine operator work.
Highly mechanized forestry operations are essential for efficient timber harvesting. Therefore, the skills of harvester operators appear to be key to productive and sustainable use of the machines. Recent research has revealed a knowledge deficit regarding the work practices of forest machine operators. This urges systematic research into forestry machine handling and a corresponding refinement of analytical methods. Current analyses of operator tasks in forestry are less formalized and focus predominantly on machine efficiency and overall performance, but not so much on the human-related conditions of work performance and workload. Therefore, the objective of this paper is to introduce hierarchical task analysis (HTA) into forestry science. HTA is a versatile, formalized human-factors method that can be used to describe the work objectives of forest machine operators. HTA is suitable, for example, for describing (in)efficient work practices and thus as a basis for designing machine operator training and for systematically evaluating assistive technologies. The task analyses in this paper draw on a recently published empirical approach to analyzing work practices, workflows, and machine operator behavior for optimal human–machine collaboration in forestry application research. Specifically, the main work methods of clearcutting and thinning stand in European forestry were considered, with examples from Scandinavian and German method application. The process of HTA is described and a prototypical approach to HTA for both working methods provided. As a result, this work could show that a single work practice affects operator goals within different work elements and sets out how inefficient work practices can be described in terms of operator goals. With the introduction and exemplary application of HTA, a structured task definition in human-centered approaches is encouraged to analyze work practices, workflows, and machine operator behavior for optimal human–machine collaboration in forestry application research.
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