The current Federal Motor Carrier Safety Administration (FMCSA) hours of service (HOS) regulations for freight-carrying commercial motor vehicle (CMV) drivers prescribe that drivers: * May drive 11 hours within a 14-hour window after coming on duty following 10 consecutive hours off duty. * May not drive after 60/70 hours on duty in 7/8 consecutive days. * May restart a 60/70-hour period after taking 34 or more consecutive hours off duty (the 34-hour restart provision). The scientific evidence supporting the 34-hour restart rule is limited, and the rule may present problems in light of the current state of sleep science. Specifically, the rule does not take into account the well-described circadian rhythms in both performance and sleep propensity. Depending on circadian placement of both the sleep opportunity and the period of on-duty time, the current restart provision may be (in the case of adverse placement of sleep and work relative to circadian phase) inadequate to restore performance and may be (in the case of optimal placement of sleep and work relative to circadian phase) adequate or even unnecessary to sustain performance. The FMCSA has commissioned scientific studies to evaluate the efficacy of the current 34-hour restart rule and to provide information in support of possible revisions to this rule. The objective of this project was to determine the effectiveness of the current 34-hour restart provision in the HOS regulations governing freight-carrying CMV drivers with regard to restoring performance. Specifically, the effectiveness of the 34-hour restart provision was evaluated using an in-laboratory experimental study design that tested cognitive task and driving simulator performance. (Author/publisher) For the full final report, see http://www.fmcsa.dot.gov/facts-research/research-technology/report/Rest…
Abstract