Driver fatigue is an important safety issue for long-haul truck drivers. To provide an efficient means of obtaining sleep, long-haul truck drivers often use tractors equipped with sleeper berth units. Depending on the type of cargo and distances traveled, long-haul truck drivers either drive in teams or alone as single drivers. Team drivers, therefore, typically sleep in a moving truck whereas single drivers sleep in a stationary truck. It has been hypothesized that sleeping in a moving truck could adversely affect the sleep quality and, therefore, the alertness level of team drivers. A naturalistic data collection system was developed and installed in two Class 8 heavy trucks. This trigger-based system consisted of vehicle sensors and cameras that allowed the experimenters to obtain the driving performance and driver alertness data for analysis of fatigue. Fatigue was measured using both objective and subjective measures that were recorded before and after sleep and while driving. Fatigue and driving performance were compared for single versus team drivers to determine which driver type acquired the greatest sleep deficit during a trip. Results suggest that single drivers were more frequently involved in critical incidents while exhibiting extreme drowsiness than were team drivers by a factor of 4 to 1. These results are discussed in relation the general safety of single versus team truck operations.
Abstract