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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles containing the keyword 'time studies'.

Category: Research article

article id 134, category Research article
Dan Bergström, Urban Bergsten, Tomas Nordfjell. (2010). Comparison of boom-corridor thinning and thinning from below harvesting methods in young dense Scots pine stands. Silva Fennica vol. 44 no. 4 article id 134. https://doi.org/10.14214/sf.134
At present, only a small proportion of the potential extractable bioenergy from young dense forests in Sweden is utilized. The conventional mechanized first thinning systems used in such stands suffer from low productivity, so the operation is only profitable in stands with bigger trees and high standing volumes. Conventional harvesters are used for this operation equipped with accumulating felling heads designed for handling several trees during each crane cycle. In thinning from below the felling and bunching work requires many time-consuming non-linear crane movements to avoid felling or damaging of future crop trees. However, higher productivity can be achieved when trees between strip roads are harvested in about 1 m-wide corridors with a length corresponding to the reach of the crane. We refer to this operation as boom-corridor thinning. The objective of this study was to compare felling and bunching productivity in young dense stands when employing thinning from below or boom-corridor thinning. Experiments were performed using a randomized block design involving between 4400 and 18 600 trees x ha-1 with a corresponding average tree size of 7.2 and 3.2 cm dbh, respectively. Based on the average tree being removed at a dbh of 5.7 cm, the productivity (ODt x PW-hour-1) was significant (almost 16%) higher for the boom-corridor thinning than for thinning from below treatment. At the same time, the time taken for the work element “Crane in-between” (the period between the loaded crane starting to move towards a tree and the felling head rapidly slowing down for positioning) was significantly reduced, by almost 17%. The positive results were achieved even though the operator was new to the method. To achieve a significantly higher efficiency during the felling and bunching operation, development of new harvesting equipment and operating techniques seems crucial.
  • Bergström, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail: dan.bergstrom@srh.slu.se (email)
  • Bergsten, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail:
  • Nordfjell, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail:
article id 264, category Research article
Yrjö Nuutinen, Kari Väätäinen, Jaakko Heinonen, Antti Asikainen, Dominik Röser. (2008). The accuracy of manually recorded time study data for harvester operation shown via simulator screen. Silva Fennica vol. 42 no. 1 article id 264. https://doi.org/10.14214/sf.264
The aim of the study was to investigate the effect of work experience on the accuracy and variation of observers recording the operation time of a harvester. A simulated thinning operation using a harvester, shown as video via a television screen in laboratory conditions, was observed by 20 inexperienced students and 10 experienced work study researchers. All the observers timed the different work elements of the harvester work with special fieldwork timers. The duration of different work elements measured by the human observers were compared to the corresponding recordings by the harvester’s automated data collector. Although the inexperienced students made more measurement mistakes than the experienced researchers, the differences in measurement error averages were not statistically significant between the groups. However, the variances of tree specific errors were significantly higher in the measurements done by the students. As inexperienced recorders, the students were not able to properly record short work elements, which lasted a maximum of 4 seconds. Due to systematic measurement errors, there was a large variation in the timing structures of the work elements among all observers. Observers’ skills and experience seems to affect measurement accuracy and thus the derived results, especially in intensive time studies. Therefore, the recorder should receive detailed training and practical experience in timing of different work elements of forest operations. In the future, with the use of automated data collectors time studies with large, detailed and accurate data will be implemented. However, due to the varying timing conditions in the forest, manual data collection is still required because of its greater flexibility.
  • Nuutinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: yrjo.nuutinen@metla.fi (email)
  • Väätäinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Heinonen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Asikainen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Röser, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:

Category: Article

article id 7445, category Article
Jaakko Vöry. (1954). Puutavaran valmistuksen keskityötulosten määrittäminen tilastoteitse. Acta Forestalia Fennica vol. 61 no. 33 article id 7445. https://doi.org/10.14214/aff.7445
English title: Statistical determination of the average work performance in the preparation of timber.

Work studies conducted in Finland and Sweden on forest work have shown that the performance of different workers or even of a same worker vary greatly, although external conditions such as the size and other properties of the trees, weather etc. are similar. It has been decided in the Northern Countries that as it is impossible to assess the working speed of a man, it is not possible to find out the average work performances, not even from long term time studies. The only way is to collect performance statistics.

Metsäteho (Forest Work Studies Section of the Central Association of Finnish Woodworking Industries) has collected since 1946 statistics on the working sites of forest industry companies in different parts of Finland on the preparation on timber. To make it comparable the material has been converted to uniform values by using the ratios given by the work time studies of various forest jobs conducted by Metsäteho. The ratios are necessary in trying to determine average performances by statistical means. The actual length of time each man is at work on different days and the actual number of days is needed, because in Finland the workers can themselves decide fairly freely the length of a working day. In forest work, wages are paid for the quantity prepared, not for time. The statistics collected by Metsäteho include information on the length of the working days, and conditions in each forest, such as the size of the trees, form of stem, branchiness, bark thickness, terrain, density of the forest, weather conditions etc.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.

The PDF includes a summary in English.

  • Vöry, ORCID ID:E-mail:
article id 7426, category Article
Olli Makkonen. (1954). Metsätöiden vertailevan aikatutkimuksen periaate. Acta Forestalia Fennica vol. 61 no. 14 article id 7426. https://doi.org/10.14214/aff.7426
English title: The principle of comparative time studies in forest work.

The origins of time study has been in the need to streamline industrial work. One of the differences between industrial and forest work is that in forest work the working conditions are subject to continuous changes. The work is also strenuous, and physical strength may come into its own in addition to skill. For these reasons, the product of a worker per time unit varies in forest work much more than in industrial work.

In industrial time studies, determination of working tempo is, besides measurement of working time, vital when calculating the normal work performance. In the Northern Countries, it has been concluded that it is impossible to determine the working tempo of a forest worker. A so-called comparative time study in which a study is made of the work performances of the same workers at different jobs and in different conditions so that the measured working times are directly comparative. Also, the requirements made for the extension of time study material are considerably greater than in Central European time studies. It is believed that the workers subjected to time studies must be observed for at least a week in each kind of work studied if the results are to be considered reliable.

The Silva Fennica issue 61 was published in honour of professor Eino Saari‘s 60th birthday.

The PDF includes a summary in English.

  • Makkonen, ORCID ID:E-mail:
article id 7401, category Article
Veijo Heiskanen. (1950). Tutkimuksia pinopuutavaran proomuun lastauksesta. Acta Forestalia Fennica vol. 58 no. 1 article id 7401. https://doi.org/10.14214/aff.7401
English title: Investigations on loading piled wood into barges.

In Finland, transportation of wood by vessels has decreased, but is still an important mode of transport especially for firewood. In 1941-1947, nearly 25% of the firewood procured by the State Fuel Board was transported by vessels. This investigation concentrates on loading of wood into barges, since the share of wages of total expenses is greatest in this phase. The loading work amounts to nearly 40% of the total wages.

Two methods of loading barges are used in Finland: loading from the shore and truck loading. This study concentrates on the more common method, loading from the shore. A time study was conducted on the different stages of loading and piling wood into barges, most of which is done by hand. Most time-consuming part of the work is transporting the logs to the barge with a wheelbarrow, comprising over 40% of the working time. Time required for loading firewood is almost twice as much as loading pulp wood. Recommendations for loading places and organization of work are given in the article to improve the efficiency of the work.

The PDF includes a summary in English.

  • Heiskanen, ORCID ID:E-mail:
article id 5564, category Article
Jerry Johansson. (1995). Backhoe loaders as base machines in logging operations. Silva Fennica vol. 29 no. 4 article id 5564. https://doi.org/10.14214/sf.a9215

Time studies and an ergonomic assessment were carried out in logging operations for three logging machines based on backhoe loader chassis. The time studies were completed with a follow-up study of one backhoe loader-based single-grip harvester. The studies indicated a productivity at the same level as that of specialized Nordic logging machines. Ergonomics also proved to be good. Mean ground pressure exerted by the backhoe loader-based logging machines was little higher than for some of the conventional Nordic single-grip harvesters to which it was compared. The ability of the machines to operate in the terrain was also good, even in rough terrain.

These machines can also be used for other jobs, such as ditch digging, road building and road maintenance. The machines then function more as carriers for attachments rather than custom-built backhoe loaders. By more careful planning of operations, the machines can be used to a higher degree and more effectively. The relatively low investment cost compared to many custom-built Nordic logging machines also contributes to a reduction of operating costs.

  • Johansson, ORCID ID:E-mail:
article id 5304, category Article
Jimin Tan. (1987). A method to evaluate productivity of logging machines. Silva Fennica vol. 21 no. 1 article id 5304. https://doi.org/10.14214/sf.a15461

This study deals with the evaluation of logging machines. The analyses were based on the results of a productivity study with special reference to a PIKA 35 processor, a delimber-bucker, working in Kyröskoski forest area in Finland. Factors affecting the productivity of the machine were surveyed. Mathematical models for determining the productivity were developed and their practical applications to the particular problem under study was demonstrated.

The PDF includes an abstract in Finnish.

  • Tan, ORCID ID:E-mail:
article id 4874, category Article
Matti Kärkkäinen. (1973). Runkojen järeys puunkorjuun monitoimikoneiden ajanmenekin ennustamisessa. Silva Fennica vol. 7 no. 1 article id 4874. https://doi.org/10.14214/sf.a14704
English title: The size of stems in estimating the time consumption of processors.

The problem considered in this paper is how to analyse the usefulness of some average volume values of stems in predicting the average time consumption of some processors. In this connection, the usual arithmetic mean, the arithmetic mean weighted with volume and the geometric mean were used. The functions describing the dependence of time consumption per tree on the volume of the tree were obtained from previous studies, as were the stand properties.

The results were obtained with the aid of computer simulation techniques and the deterministic model described above. According to the results, the usual arithmetic mean is very applicable for predicting the time consumption. The geometric mean is nearly as good, or in some cases even better. However, as a rule its computation is much more tedious than that of the arithmetic average volume for the purpose.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
article id 4867, category Article
Matti Kärkkäinen. (1972). Näkökohta keskimääräisestä tuotoksesta metsätyötieteessä. Silva Fennica vol. 6 no. 2 article id 4867. https://doi.org/10.14214/sf.a14670
English title: A point of view on the average output in forest work science.

The paper deals with the concepts of time consumption and output in forest work science. When output is defined as the inverse of time consumption and vice versa, it is possible to show the important consequences in probability functions. For instance, it is not the same if the dependent variable in a regression analysis is output or time consumption. Also, the average differ depending on if they are based on the time consumption figures or on the average output.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
article id 4720, category Article
Veijo Heiskanen. (1963). Aikatutkimuksia koivun karsimisesta. Silva Fennica no. 115 article id 4720. https://doi.org/10.14214/sf.a14279
English title: Time studies in the pruning of birch.

On the basis of time studies on pruning, one thousand stems in four stands was pruned, carried out in 1962. The work was done in two phases with Olli pruning saw, first attached to a shaft about 1.8 metres long and the to a shaft about 4 metres long.

The total time of moving from one stem to another when pruning the stem varied from 0,28 to 0.31 min per stem in the different working sites. The resting time was 19–20% of the effective working time, which included actual pruning time and the moving time. In average, 7.5% of the actual pruning time was unproductive. The actual pruning took in average 0.75–1.1 min/stem in the different sites. The time depended on size of the tree, the DBH, and on the length of the part to be pruned. The total working site time for the pruning was in average 1.34–1.98 min/stem. The output of the work per 7 hours’ working day varied from 226 to 280 stems, and the costs from 10 to 14 pennies per stem.

The PDF includes a summary in English.

  • Heiskanen, ORCID ID:E-mail:
article id 4706, category Article
Pentti Nisula. (1961). Aikakello- ja pistokoemenetelmän vertailu. Silva Fennica no. 112 article id 4706. https://doi.org/10.14214/sf.a14233
English title: A comparison between the stop-watch method and the random-sample method.

The aim of this study was to find out to what extent it is possible to time phases of work by making instant observations at regular intervals according to the principles of the method of random samples, and arrive at similar results as obtained by timing continuously with a decimal-minute stop watch. In the first mentioned method the observer of the time study is given a sound signal at even intervals, in this case each 1/10-minute period, during the signal he records the phase of work (element) the object is performing.

The material of the study consists of studies in skidding and loading in connection with transportation by tractor during a period of 8 days. The duration of each element in using tractor hand in skidding and hauling was measured with an ordinary stop watch using repetitive timing. This material was then converted into random sample material.

The analysis of the material showed that the method of random samples yielded observations from all phases of work present in the material obtained by measuring with the stop watch. The duration of elements as determined by the random-sample method were of the same order as determined with stop watch. The results did not cause any observable systematic deviation or rhythmic repetition of elements.

The PDF includes a summary in English.

  • Nisula, ORCID ID:E-mail:

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