Abstract
To be characterized as sustainable, forest operations need to be studied and validated from many points of view, including their productivity, ergonomics and costs. In most of these areas, performance enhancement was found to be sustained by the development and use of mechanization, including that of landing operations done to process small-sized trees. For these, an affordable and sustainable alternative could be that of using double-grip processors. However, there is a lack of information characterizing their capability and performance, which was one of the main reasons for carrying on this study. Observational data were collected over four operational days for a HYPRO 775 double-grip processor to estimate the productivity, exposure to noise and cardio-vascular workload in processing small-sized trees at landing. Miniaturized dataloggers and video recording were used to document close to 28 h spent at the workplace and 15 h of operation, respectively. A time study was used to estimate the productive performance and the commonly used metrics were computed to evaluate the exposure to noise and cardio-vascular workload. A delay-free work cycle was framed around a processed tree and it took, on average, ca. 45 s. Based on 901 processed trees (average height of ca. 12 m and average breast height diameter of ca. 12 cm), the net productivity rate was estimated at ca. 65 trees per hour (ca. 224 logs of 2.4 m produced per hour). While the cardiovascular activity indicated light work, exposure to noise seems to be a concerning problem to be addressed in the future, given the figures found (A-weighted sound pressure level higher than 85 dB(A) and the sound pressure level normalized for a nominal day of 92.79 dB(A)). This becomes even more important as this study found a machine utilization rate of ca. 60%, therefore an extension of productive time could increase the exposure to noise. We conclude that double-grip processors represent a valuable technical alternative in processing small-sized trees at landing if supplementary precautions would be taken against exposure to noise. These may rest very well in the awareness and behavior of the operators as well as in wearing protective equipment.
Highlights
Sustainability of forest operations is included in the current scientific discourse, being often studied by the approach of balancing their productivity, operational costs, environmental impact and ergonomics, to name just few of the currently described scientific areas in the related sciences [1,2]
It is commonly agreed that the increment of operational performance has been enabled by the development of mechanization in operations [3]; it has been further enhanced by the introduction of innovative and modern machines [4,5], decisively contributing to the improvement of operational sustainability
The impossibility to compare the results was due to the fact that most of the literature on double-grip machines was found to be published in the 90 s and it was not available in English for a detailed comparison. It refers to double-grip harvesters used for tree felling and processing operations deployed in forest stands [23], making it difficult to compare the results due to different inputs and operational environment of this study; the study of [23] compared the productivity of single- and double-grip harvesters, concluding that there were rather minor differences in terms of productive performance in tree felling and processing operations deployed in shelterwood silvicultural systems
Summary
Sustainability of forest operations is included in the current scientific discourse, being often studied by the approach of balancing their productivity, operational costs, environmental impact and ergonomics, to name just few of the currently described scientific areas in the related sciences [1,2]. It has contributed to a productivity increment, especially in selective cuts in which a high number of logs are to be recovered from a given tree [6], and to the ergonomics and safety of the workers [7,8], which are known to be far poorer in the case of motor-manual operations [3,9,10]. The mechanization level of tree processing operations varies widely in different regions of the world [6,11]. This limits the use of some harvesting methods, generally shaping a situation for which sound solutions need to be developed [12]
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