Roland Wenhold,Pierre Ackerman,Simon Ackerman & Kayla Gagliardi
Pages 9-18 | Received 08 Aug 2018, Accepted 01 Feb 2019, Published online: 01 Mar 2019
Abstract
In this study, a South African pine sawtimber mechanized cut-to-length harvesting operation was analyzed with the objective of modelling productivity development learning curves of beginner operators in both clear-felling and thinning operations. Trainee operators were selected based on the results of an assortment of psychometric testing and subsequently completed several harvester simulator tests. On average, a trainee operator would start at aperformance level (PL) of 60% lower than the population’s mean test time per test (PTmean) and end with a PL of 22% higher than the PTmean. Furthermore, when the PL of an average simulator trainee was measured over a period of 8.4 days or 25.2 tests (three tests per day), the operator’s PL was improved by 200%. Following sufficient simulator training, the operators began working in-field. Thinning operators worked with an average tree size of 0.18 m3, starting at a productivity of 13.71 m3 per productive machine hour excluding delays longer than 5 minutes (PMH5) at month one and increasing their productivity to 38.96 m3·PMH5-1 by the end of month 12. Clear-felling operators worked with an average tree size of 0.54 m3, starting at a productivity of 27.56 m3·PMH5-1 at month one and increased their productivity to 43.75 m3·PMH5-1 by the end of month 12. Ultimately, the thinning and clear-fell operators reached the end of their learning curves after an average of 9 and 6.5 months, and increased their productivity performances by 218% and 104%, respectively. These findings suggest acceptable learning periods and performance increases for beginner harvester operators.
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