Time consumption, productivity, and cost analysis of skidding in the Hyrcanian forest in Iran

The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions.An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Iran for improving production rate of skidding and finding out the production cost for planning.Based on the identified elements of skidding work phase and 130 recorded cycles,we calculated the models for effective time consumption,total productivity,and unit cost.The validity of the model was tested at 95% confidence interval.The average load volume per cycle was 2.82 m 3,average one way skidding distance was 450 m,and the average slope was 18%.The average travel speed of unloaded skidder was 5.8 km·h-1,and the average speed of loaded skidder was 0.1 km·h-1 higher than the speed of the unloaded ones.The travel speed was predominantly affected by longitudinal slopes and types of strip roads.The average speed of pulling the cable was 1.16 km·h-1,and that of load winching was 0.74 km·h-1.The average outputs in skidding was 10.6 m 3 ·h-1 and the unit cost was 12.1 US$ per hour.The time consumption and productivity of skidding depends on distances and slope,number of logs per cycle,volume,log length,etc.However,the influence of variables is not the same.