The objective of this research project was to determine the effectiveness of the 34-hour restart provision in the Hours-of-Service regulations governing property-carrying commercial motor vehicle drivers. A sample of 27 healthy subjects was studied in an in-residence laboratory study with frequent testing of cognitive performance and driving performance on a high-fidelity driving simulator. A “worst-case”–”best-case” between-groups comparison was made of two 5-day (14-hour/day) work periods separated by a 34-hour restart period. Half the sample was randomized to the “best-case” condition, which entailed daytime wakefulness and work (and nighttime sleep) throughout the study. The other half was randomized to the “worst-case” condition, which entailed nighttime wakefulness and work (and daytime sleep) during the two 5-day work periods, while transitioning back to a daytime schedule during the 34-hour restart period. In the “best-case” condition, performance was the same before and after the 34-hour restart. In the “worst-case” condition, however, performance after the 34-hour restart was impaired relative to performance before the restart, indicating that the restart period was not effective at maintaining performance in this condition. Driver fatigue could be reduced by establishing work schedules and adapting HOS regulations that allow greater flexibility (e.g., taking into account strategic napping and circadian timing). (Author/publisher)
Abstract