Development of Updated Models to Characterize Skidding Performance in Romania Based on a Nation-Level Dataset

Skidding is one of the most important methods for wood extraction globally, necessitating updated models to assess its performance based on the technical characteristics of the fleet in use. Based on a nation-wide, all-season dataset, this paper aimed to develop time and fuel consumption models for currently used cable skidders and farm tractors fitted for skidding in Romania. Although some statistical assumptions were not met, our models characterized the performance well in terms of time and fuel consumption, allowing for a differentiation in performance between skidders and farm tractors. For skidders, cycle time was explained to a degree of 58% (R2 = 0.58) by payload volume, number of pieces, and extraction distance, highlighting the importance of these variables when assessing cycle time performance of machines equipped with a double-drum winch. In contrast, for farm tractors, cycle time was explained solely by extraction distance (R2 = 0.87), which indicates a lower variability induced by payload size and number of pieces for machines equipped with a single-drum winch. Similar models were developed for fuel consumption, showing the significance of payload volume and extraction distance for skidders (R2 = 0.54) and extraction distance alone (R2 = 0.75) for farm tractors. Beyond an extraction distance of 50 m, the productivity of farm tractors decreased sharply, reaching half of that of skidders at an extraction distance of 1500 m, indicating a better time and fuel consumption performance of skidders, particularly in the case of excessively long extraction distances. Further studies should focus on finding effective methods and developing automated systems able to track the performance of operations and keep the pace with improvements in machine performance.