Productivity Analysis of an Un-Guyed Integrated Yarder-Processor with Running Skyline

An excavator-based integrated yarder-processor was evaluated in a clearfelling in centralNorway. The machine is unique because, as it uses a running skyline setup, yarding and processing cannot take place simultaneously as is the case with many European integrated tower yarders. Felling productivity was 10.6 m3 E15h-1, yarding 9.2 m3 E15h-1 and processing 10.9 m3 E15h-1. Given that yarding and processing take place alternately accounting for 54%and 46% of a system hour, the overall system productivity was 4.9 m3 E15h-1 (processed and stacked). The processing rate was approximately 30% of what is achieved by single grip harvesters, indicating the effect of space limitations, a possible over-dimensioned processing head, and the need to simplify the assortment list under such conditions. An increase in processing productivity would require a second feller-chokersetter in the crew, although neither would then be used to full capacity. Un-choking alone accounted for 19% of the yarding cycle timeand might be reduced by applying self-releasing chokers. System productivity needs to beincreased by 30–50% to make it competitive. Much of this could be achieved simply by deploying the machine in stands with larger mean tree volumes than those observed (0.27 m3).