Tuyển tập những bài báo cáo nghiên cứu khoa học hay nhất được đăng trên tạp chí JOURNAL OF FOREST SCIENCE đề tài: Comparison of three methods to determine optimal road spacing for forwarder-type logging operations. | JOURNAL OF FOREST SCIENCE 55 2009 9 423-431 Comparison of three methods to determine optimal road spacing for forwarder-type logging operations M. R. Ghaffarian1 K. Stampfer1 J. Sessions2 -Department of Forest and Soil Sciences Institute of Forest Engineering University of Natural Resources and Applied Life Sciences Vienna Austria Department of Forest Engineering College of Forestry Oregon State University Corvallis USA ABSTRACT Optimum road spacing ORS of forwarding operation in Styria in Southern Austria is studied in this paper. In a harvesting operation it is important to compute the ORS to minimize the total cost of harvesting and roading. The aim of this study was a comparison of different methods to study ORS. Data from 82 cycles were used to develop two models for predicting the cycle time using statistical analysis of a time study data base. The ORS was computed by three methods including Matthews formula 1942 Sundberg s method 1976 and the two statistical models for predicting the cycle time. The results gave the ORS for one-way forwarding using Matthew s formula as 1 969 m Sund-berg s model as m and the two time study models as 463 and 909 m. The analysis of forwarding data indicated that the speed was related to a distance which contributed to the difference between models and that the loading and unloading time may be related to one or several other study variables. Keywords forwarding production cost travelling model optimum road spacing Road network planning is an important part of logging planning. The optimized road network can help minimize harvesting costs. To optimize the road network optimum road density and spacing should be analyzed. In Austria the road density is m ha for small forests less than 200 ha m ha for private forests m ha for federal forests and average 45 m ha overall . Matthews 1942 developed a model to define optimum road spacing based on minimizing the total cost of skidding and roading from
