عنوان مقاله [English]
Managers of logging operation are faced with profit reduction due to rapid increases in equipment costs, rapid depreciation of equipment and changing logging systems from harvesting the large trees to the smaller ones. The simplest way to confront this problem is improving the efficiency of the logging operation. Using work study methods, the required information for this purpose can be obtained. The aim of this study was to develop skidding time estimation model, skidding unit cost and productivity estimation of Timberjack- 450C skidder in two skidding directions and under combined logging system (tree length, long wood and short wood systems depending on different situations). The results show that skidder productivity rate in uphill skidding is 16.31 m3/hr and greater than its productivity in downhill skidding (12.32 m3/hr). Changing of logging system (using combined system (with 14.31 m3/hr productivity rate) rather than short wood system (8.88 m3/hr) gives rise to the increase of productivity rate. The Timberjack- 450C production cost which was working under contract was 145000 rials/ m3.