Fatigue assessment of forklift operators in a 12-hour shift system

Background

In recent years, numerous large-scale manufacturing enterprises in Northeastern China have shifted from the conventional 8-h shift model to an extended 12-h shift schedule. While this change aims to improve production efficiency, prolonged working hours may lead to increased levels of occupational fatigue and pose significant risks to worker health and safety.

Objective

This study aimed to assess the physiological and subjective fatigue responses among forklift operators working 12-h shifts, with particular emphasis on differences between day and night shifts, as well as gender-based variations in fatigue susceptibility.

Methods

Ten forklift truck operators were recruited from a major tire manufacturing enterprise that had implemented a 12-h shift system. Subjective fatigue was measured through self-reported assessments, while objective indicators were captured using surface electromyography (sEMG) and electroencephalography (EEG). Data were collected at multiple time points across both day and night shifts to monitor changes in fatigue levels.

Results

Findings revealed that most operators experienced significant fatigue after 8 h of work, even when shifts extended to 12 h. Fatigue and drowsiness symptoms were more pronounced among night shift workers, with critical fatigue peaks observed between 14:30–16:00 and 2:30–4:00. Gender-based analysis showed negligible differences in daytime fatigue; however, female operators exhibited greater fatigue and drowsiness during night shifts compared to male counterparts.

Conclusions

Extended 12-h shifts are associated with considerable fatigue, especially during night work, posing potential safety concerns in industrial environments. The identification of specific fatigue-prone periods and gender-related differences underscores the need for tailored fatigue risk management strategies and evidence-based shift scheduling policies to safeguard worker well-being and operational safety.