Operator work-related musculoskeletal disorders during forwarding operations in South Africa : an ergonomic assessment

Abstract

Forest machine operators are still experiencing Work-Related Musculoskeletal Disorders (WMSD’s) despite extensive mechanisation and modernisation of harvesting systems. However paucity of local ergonomics research and technology transfer problems may affect the use 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. Operators reported hourly, localised work-related musculoskeletal discomfort experienced during the shift. A video camera mounted in the cab was used to capture footage of awkward head postures. The video footage was also used for the WMSD risk assessment using the Health and Safety Executive (HSG60) upper limb disorder assessment worksheets. Operators reported having experienced WMSD’s during the last 12 months mainly in the lower back, neck, shoulders and upper back. The studied operators reported lower repetition strain symptoms and higher lower back disorders than in previous studies. Twenty three percent of the awkward head postures adopted were extreme. The study results support the assertion that causal pathways of WMSD’s 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.