Effects of the number of assortments and log concentration on time consumption for forwardingManner J., Nordfjell T., Lindroos O. (2013). Effects of the number of assortments and log concentration on time consumption for forwarding. Silva Fennica vol. 47 no. 4 article id 1030. 19 p. Highlights• We analysed the effects of total and forwarded log concentrations (m 3 (100 m) -1 ) and the number of loaded assortments on forwarding.• The combination of the number of loaded assortments and their abundance (i.e. forwarded log concentration) affected time consumption most. • This knowledge enables improved efficiency by optimizing number and assortment proportions in the various loads required to forward a stand. AbstractForwarding 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 3 was significantly affected by the number of assortments that were loaded, but only the "driving while loading" 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.

Highlights• Recent developments in on-board technology enables automatic collection of follow-up data on forwarder work.• Time consumption per load was more strongly associated with Loading drive distance than with extraction distance, indicating that the relevance of extraction distance as a main indicator of forwarding productivity should be re-considered.• Data, within variables, were positively skewed with a few exceptions with normal distributions. AbstractRecent 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), Loading, Unloading, Driving empty, Driving loaded and Other time 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 Driving empty and Driving loaded, but minor proportions for the work elements Loading and Unloading. Based on the means, the crane was used during 74.8% of Loading PM time, the driving speed was nonzero during 31.9% of the Loading PM time, and Simultaneous crane work and driving occurred during 6.7% of the Loading PM time. Time consumption per load was more strongly associated with Loading drive distance than with extraction distance, indicating that the relevance of extraction distance as a main indicator of forwarding productivity should be re-considered.

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Factors affecting forwarding work are interesting because they can be used to better optimize forwarding routes and to predict costs. The main objective of this study was to investigate the association between driving speed and driving distance when forwarding. Data was automatically collected during 2.5 years from two large forwarders operating during final felling in central Sweden. Driving speeds for the work tasks Driving unloaded, Loading drive and Driving loaded were analysed using correlation, least-squares regression, and quantile regression. The results showed that speed and distance were strongly correlated for the work element Driving unloaded, while the correlation was weaker for Loading drive and Driving loaded. Possible factors leading to these results are as follows: longer travelling distances stimulate better planning and the establishment of better extraction roads; operators may feel stressed and drive faster as travelling distance increases; and finally, the relative influence of accelerations and decelerations decreases with increasing driving distance. Also, the use of quantile regression was successful and provided information that normal least-squares regression does not provide.

Highlights• Boom-tip control saves time compared to the conventional system. • This study introduced a field-study design enabling establishment of causal relationships during ordinary forwarding operations. • Although the study design requires some extra arrangements, it efficiently combines the representativeness of conventional follow-up datasets with establishment of causal relationships that traditionally have been possible only through observational time studies or standardized experiments. AbstractCrane work is the most time-consuming work element in forwarding. Hence, assist systems like boom-tip control are of interest. The first commercially available boom-tip control for forwarders was introduced in 2013. In this study we analysed whether replacing conventional boom control (CBC) with John Deere's version of boom-tip control (named Intelligent Boom Control, IBC), increases crane-work productivity. We used data automatically gathered from 10 final-felling stands, covering typical logging conditions for southern, central and northern Sweden. Two John Deere 1510E and two John Deere 1910G forwarders were operated by seven experienced operators during the follow-up study, covering 1238 loads in total. A split-plot design was applied to isolate effects of the boom-control system being used (CBC, IBC). We found that using IBC for loading work (crane work and driving included) saved 5.2% of productive machine time compared to using CBC (p ≤ 0.05). The corresponding saving when using IBC for unloading work was 7.9% (p ≤ 0.05). Depending on geophysical factors, this corresponds to approximately 4% savings in productive machine time for forwarding as a whole, including pure transport (with and without load). Moreover, the study introduced in cut-to-length context a novel field-study design to collect a large follow-up dataset in the course of ordinary forwarding operations. We found the study design to be a cost-efficient way to combine the representativeness of conventional follow-up datasets with the ability to establish causal relationships. Establishment of causal relationships has traditionally been possible only through observational time studies or standardized experiments. Silva Fennica vol. 53 no. 2 article id 10161 · Manner et al. · Comparing forwarder boom-control systems based …