Dep. of Forestry, Faculty of Natural Resources, Tehran University, Karaj, Iran, P.O.Box: 31585-4314.
The optimum road spacing has been studied by many researches. It is an important step of forest road network planning. The goals of this study are determining the optimum road spacing in Kheiroudkenar forest of Nowshahr in Northern Iran and study of effect of kind of skidder on skidding cost and road spacing. Continues time study method was used to determine the production rate of TAF and Timberjack 450 C skidders in two districts of Kheiroudkenar forest. The production models were developed using stepwise regression method with 46 working cycles for TAF and 44 for Timberjack. The total road construction and skidding cost were calculated for different road spacing for both skidders in one-way and two-way skidding. Based on minimizing the sum of the road and skidding costs, the optimum road spacing was estimated as 1714 m and road density of 5.8 m/ha for two-way skidding by Timberjack and estimated optimum road spacing of TAF was 1600 m and road density of 6.25 m/ha. For one-way skidding, the optimum road spacing of Timberjack was 1143 m and road density of 8.8 m/ha, for skidding by TAF, the optimum spacing was estimated as 1114 m and road density of 8.97 m/ha. The existing road density of Timberjack and TAF skidding sites was 28.16 and 17.11 m/ha respectively which are higher than optimum density. The study of variants method is applied to find the optimal network for existing network in Namkhaneh district