Fatigue risk associated with extended off-duty periods and circadian misalignment: An exploratory truck driver fatigue risk model

Background: Road freight transportation in South Africa is vital to the economy, but truck driver fatigue poses safety risks, leading to crashes and reduced performance. Fatigue is influenced by work schedules, driver health and sleep patterns. Objectives: This study analyses work scheduling factors contributing to fatigue, focussing on recovery between shifts, cumulative workload, waiting times and clock-in patterns. Method: This study examines the risk of fatigue among truck drivers by applying logistic regression, fitted with ridge regression, to scheduling and fatigue telematics data from a South African road freight carrier. Hypotheses explored the association of scheduling practices that restrict truck drivers’ rest and their fatigue risk. Results: Longer recovery times were associated with increased fatigue risk, suggesting the quality of off-duty rest is more important than duration alone. Night-time rest between 00:00 and 06:00 was crucial in reducing fatigue risk, while working during these hours heightened the risk. A higher cumulative workload over the week, however, was associated with reduced fatigue risk, raising questions about drivers’ use of off-duty time and the importance of routine schedules. Conclusion: Fatigue management is complex – simply extending off-duty hours may not reduce fatigue if drivers struggle to readjust or use rest time ineffectively. Ensuring night-time rest and managing work hours are critical strategies. Contribution: Carriers should go beyond extending rest periods by aligning schedules with circadian rhythms and prioritising driver well-being to enhance safety and performance.