Productivity and workload analysis between manual and motor-manual pruning of Pinus patula at two different lifts

Abstract

ABSTRACT Tree pruning is integral to sawtimber production in South Africa, the main purpose being the production of knot-free wood and access for fire protection. Although handheld pruning tools have been used for decades, motor-manual tools have recently been introduced. However, knowledge of possible ergonomic risks and possible productivity associated with either pruning method is limited in the literature. Hence the objective of this study was to assess human workload associated with, and possible productivity gains of, motor-manual pruning against manual operations in 2.0 m and 3.5 m pruning lifts in Pinus patula stands. The study was completed in two stands in the KwaZulu-Natal Midlands of South Africa. Information collected included time study and heart rate data. Time study results showed that motor-manual operations were more productive than manual operations in both the 2.0 m and 3.5 m pruning lifts. Pruning operations fall under the “medium to heavy” workload classification. These results show promise as the first steps in investigating the effect of manual and motor-manual operations on productivity and workload of pruning operations in South Africa. However, it is recommended for this study to be repeated with gender, terrain conditions, temperature, and musculoskeletal efforts as additional factors to workload and productivity.