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 m 3 ) were beneficial to the single machine system, while increased chipper productivity (40, 50 and 60 m 3  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 m 3 bin, there was a 95% probability that the single-machine system was between 0 · 18 € and 0 · 41 € m - 3 [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].