Analysis of Two Simulated In-field Chipping and Extraction Systems in Spruce Thinnings

The productivity, cost and fuel-consumption rates for two wood-chip production systems were tested using computer simulation. Both systems included the same terrain-going chip harvester. In the first system, it was supported by a bin forwarder, whereas in the second system, the chip harvester had to cease operations and extract the load once the bin was filled. A largely deterministic base simulation was carried out to illustrate the effects of machine interaction, bin size, chipper productivity, in-field extraction distance, and forest-road haulage distance. Very low turnround times and increased bin size (10, 15 and 20 m3) were beneficial to the single machine system, while increased chipper productivity (40, 50 and 60 m3 h−1) improved the feasibility of the two-machine system, irrespective of bin size. An applied simulation included a larger stochastic component, and showed that for a 15 m3 bin, there was a 95% probability that the single-machine system was between image and image [loose volume, l.v.] more costly than the two-machine system under typical Danish conditions. Fuel consumption also exceeded that for the two-machine system by between 0·24 and 0·30 l m−3 [l.v].