Finnish timber harvesting changed considerably in the late 1980s and early 1990s. For example, the interaction of machines has become more important. Simultaneously, this has brought forth a new problem: a single grip harvester and a forwarder can act together well in a conventional harvesting system, but it is difficult to join a timber truck to the system. One solution could be the use of interchangeable platforms. We built a simulation model for harvesting with CADmotion software. Furthermore, thirteen stands were generated for use as input-data in the simulation by Pukkala's Conifer Stand Simulator. The time consumption and the productivity of forest machines and trucks were calculated by recently published models. In addition, the delays of machines were simulated. In Finnish conditions the total productivity of the interchangeable platform truck is lower than that of the conventional truck. The most important reason is the transport of empty platforms between stands. The other reason is that in the conventional system the buffer can be kept appreciably larger than in the interchangeable platform system. Evidently, improvement of the truck does not improve the performance of the whole system. In the so-called hot-logging sequence, extra waiting time decreases the benefit caused by shorter loading time.
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