Abstract:
Forest machine operators are still experiencing work-related musculoskeletal disorders
(WMSDs) despite extensive mechanisation and modernisation of harvesting systems.
However, paucity of local ergonomics research and technology transfer problems threatens
the sustainability of mechanised systems in South Africa. Consequently, this study was a
field-based ergonomic assessment of local forwarding operations. PG Bison’s North East
Cape Forests (NECF) Eastern Cape operations and Komatiland Forests (KLF), Mpumalanga,
operations were studied. The main aim of the study was to carry out an ergonomic assessment
on local forwarder operator tasks, using Tigercat 1055 forwarders. The study specifically
assessed WMSD prevalence and risk factors, investigated the frequency of awkward head
postures, and evaluated work organisation.
A modified Nordic musculoskeletal questionnaire was used to survey WMSD prevalence and
work organisation factors. During the shift, operators reported localised work-related
musculoskeletal discomfort hourly. A video camera mounted in the cab was used to capture
the footage of awkward head postures. The video footage was also used for the WMSD risk
assessment using Health and Safety Executive (HSE) (HSG60) upper limb disorder
assessment worksheets.
Operators reported that they had experienced WMSDs during the last 12 months, mainly in
the lower back, neck, shoulders and upper back. The operators cited lower repetitive strain
symptoms and higher lower back discomfort than in previous studies. Twenty three per cent
of awkward head postures were extreme. Operators reported worse than normal
psychological profiles. The study results support the assertion that causal pathways of
WMSDs are complex and multifactorial. Repetition, awkward head posture, duration of
exposure, vibration, psychological factors and individual differences were identified as the
main WMSD risk factors.
