Background: Commercial truck drivers stay behind the wheel for long hours. Fatigue is thus a major safety concern among such long distance travelling drivers.
Objectives: Primarily, the study explored the effects of driving duration on commercial truck drivers’ visual features and fatigue awareness. It also examined the association between visual variables and subjective level of fatigue.
Methods: Participants of the study were 36 commercial truck drivers. During the study, the participants were grouped into nine on the basis of the differences in their age and were made to participate in the naturalistic driving test. In the driving test, the participants were asked to finish 2h, 3h, and 4h continuous driving tasks. Ten visual indicators and self awareness of fatigue level of the drivers were recorded during the driving hours. One-way ANOVA and Pearson product-moment correlation were used to analyze each visual indicator’s variation by age groups over time, and its association with subjective level of fatigue.
Results: The statistical analysis revealed that continuous driving duration had a significant effect on changes of visual indicators and self-reported fatigue level. After 2h of driving, both the average closure duration value and average subjective fatigue level changed significantly. After 4h of driving, other than the average number of saccades and average pupil diameter, all of the driver’s visual indicators had a significant change. In addition, the change of fatigue level is positively associated with the variation of pupil diameter, fixation duration, blink frequency, blink duration, and closure duration. On the other hand, the change of fatigue level was negatively related to number of fixations, search angle, number of saccade, saccade speed, and saccade amplitude.
Conclusion: Driving duration has a significant effect on driver’s visual variation and fatigue level. For commercial truck drivers, traffic laws and regulations should strictly control the amount of their continuous driving time. Moreover, driving fatigue can also be evaluated through the change rate of driver’s visual indicators. Awareness of the rate of change in their driving fatigue level alerts drivers to the risk of fatigue and rest moment. [Ethiop. J. Health Dev. 2018;32(1):36-45]
Key words: Commercial truck drivers, visual behaviors, fatigue level, Stanford Sleepiness Scale, Pearson correlation