Workability and Productivity among CTL Machine Operators – Associations with Sleep, Fitness, and Shift Work

Operational performance of fully mechanized cut-to-length (CTL) harvesting varies greatly due to the human factor i.e. the machine operator. This study investigated how CTL machine operators' workability index (WAI), personal lifestyle choices, seasons, and shift work affected operational performance. Research evaluated 14 volunteer CTL machine operators for a longitudinal study with continuous data collection of productivity, activity level, sleep, and follow-up on a workability index questionnaire and fitness test every three months over a year. The study analyzed the production of 152 745.5 m(3) of timber combined with self-tracking data. Operators' relative productivity (P-r) had an increasing trend whilst WAI increased, thus WAI seems to work well also for forestry applications. Physical fitness (VO2max) didn't seem to connect with P-r and WAI had only a slightly increasing trend when VO2max increased. The participants slept longer in the evening shift than in the morning shift (p < 0.000) consequently catching up on their sleep deficit from the morning shift period. Furthermore, operators' higher sleep value (SV) in the evening shift increased P-r in the final fellings. The results should be of interest to both practitioners and researchers interested in the productivity of harvesting operations.