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Frequently Asked Questions: Commercial Motor Vehicle (CMV) Driver Restart Study

Frequently Asked Questions (FAQs)

Study Findings
Study Design


The Commercial Motor Vehicle Driver Restart Study found that drivers using the restart rule in effect through June 30, 2013, experienced safety outcomes no different from those using the restart in effect on and after July 1, 2013. The study did not find that the requirement for at least two nighttime periods of rest and the prohibition on taking more than one restart per week provided a greater net safety benefit than the previous restart regulation, which did not include those requirements. 
The study found evidence that the restarts benefitted the ability of drivers to recover from fatigue and sleep loss regardless of the restart provision used (i.e., 34 consecutive hours off duty [Section 395.3(c)] and/or restarting in less than 168 hours [Section 395.3(d)]). It showed that there was an increase of more than 2 hours sleep obtained per 24 hours during the restart periods compared to duty days. This study provided evidence that drivers were in need of sleep when they undertook a restart, and when they slept, they slept much longer than when they were working.
Based on the findings from the study, the 34-hour restart rule in operational effect on June 30, 2013, is restored to full force and effect. The requirement for two off-duty periods of 1:00 a.m. to 5:00 a.m. in section 395.3(c) of the Agency’s hours-of-service rules will not be enforced, nor will the once-per-week limit on use of the restart in 395.3(d).


The data were analyzed to assess the operational, fatigue, safety, and health impacts of the two restart provisions (i.e., a 1-night rest period versus a 2-night rest period) on CMV drivers. The study team also analyzed the safety and fatigue effects of the restart provisions on participating drivers who had less than 168 hours between their restart periods and those who had at least 168 hours between their restart periods. All data were stripped of personally identifiable information (PII) and were integrated into a public-use data set.
Upon completion of analysis, and before being released in a public-use data set, these data were divested of PII, de-identified, and then reviewed by an Institutional Review Board (IRB) for compliance with Federal, departmental, and ethical guidelines.
No. Participating drivers’ individual data were stripped of PII and grouped with other drivers’ data for analysis. The data collected during this study are meant solely for research purposes. Releasing driver-specific data could prove damaging if intercepted and distributed inappropriately. Unique data will not be disclosed except as required by law, in conjunction with a government inquiry, or pursuant to judicial order.
No, the study team has not and will not share any carrier or driver PII with FMCSA or other government agencies.
No. Videos will not be made available to the public.
No. But drivers were asked to self-report some medical conditions.
Drivers were asked to self-report any medications and other over-the-counter stimulants as part of the survey questionnaire that they completed at the beginning of the study. However, medication use was not tracked during the 5-month data collection period. Drivers were asked to keep a caffeine log using a study-provided smartphone application.
The study contractor collected back-office HOS data from participating carriers’ fleet management or ELD systems. However, under the data sharing agreement between the contractor and each carrier, all data collected during the study were stripped of PII and developed into a public-use data set. FMCSA has no access to back-office data.
Yes, drivers used electronic logs. Drivers also wore actigraph watches that measured sleep duration while drivers were off duty.
The onboard monitoring system (OBMS) vendor for the study was Lytx (formerly DriveCam). Lytx reviewed and coded the naturalistic driving videos to verify SCEs.
Lytx coded the study videos in the same way that it codes videos for its commercial clients. The coded data for this study were securely transmitted to the study team; data were not shared with fleet managers or carriers. The coder did not know any details regarding driver schedules or restart durations.
Compared to the MAP-21 HOS Restart Field Study, this study included more than twice as many drivers, from many sectors of the trucking industry. It also covered a longer period of data collection, and utilized additional technologies to monitor safety performance. This study used onboard monitoring systems for the collection of data on SCEs. Each driver was given an opportunity to participate and contribute data for a period of 5 months.
Yes. The Consolidated and Further Continuing Appropriations Act (2015) required the Secretary to initiate a naturalistic study of the operational, safety, health, and fatigue impacts of the restart provisions. The study looked at all four domains, including driver health.
Yes. The peer review panel reviewed the draft study design and final study report.
The peer review panel included statisticians and researchers not affiliated with the U.S. Department of Transportation (USDOT) or with the institutions associated with the research team.
Drivers were not separated into different groups. Participants drove their normal, revenue-producing routes and took restarts based on their regular work schedules. Some drivers took 1-night, 2-night, and/or 3-or-more-night restarts throughout the course of the 5 months of data collection. Also, many of these drivers used the HOS provision (i.e., one or more restarts in less than 168 hours [1 week] as compared to a maximum of one restart in 168 hours).
This was a naturalistic driving study where participants drove their normal routes. Drivers were not required to make any changes to their work-rest schedules. The study team recruited drivers who were likely to have variable restart lengths (both 1 and 2 nights) and restarts that occurred both less than and at least 168 hours (1 week) apart.
Yes. This was a naturalistic driving study, so the study team simply observed what normally occurred to CMV drivers during their usual revenue-producing operations. The study team collected data to analyze restarts that lasted 1, 2, or 3 or more nights.
The study team recruited drivers whose duty schedules related to the timing and duration of duty shifts and use of the restart provision. The study team identified drivers who were likely to have different restart lengths (both 1 and 2 nights) and restarts that occurred both less than and at least 168 hours (1 week) apart. Drivers who were likely to use either of the two restart provisions were included in the study.
Yes. Driver compensation was based on the amount of time that the driver was in the study, paired with completion rates of study activities on a pro rata basis. Drivers who participated in the study for a full 5 months and completed every possible study activity could earn a maximum amount of $2,166. A detailed compensation plan was included in the informed consent agreement signed by all participating drivers (see Appendix D in the CMV Driver Restart Study Work Plan).
While it would have been ideal for all drivers to participate for a full 5 months, some drivers did leave the study before their 5-month data collection period was complete. Driver compensation was based on the amount of time the driver was in the study, paired with completion rates of study activities on a pro rata basis.
FMCSA's statisticians determined that 207 drivers were necessary; the study team's biostatistician confirmed this. The study plan was also reviewed by the independent peer review panel (which included two statisticians) and by statisticians in the USDOT Office of Inspector General (OIG). All parties concluded that it was highly likely that 207 drivers would generate statistically significant results.
Yes. Both the independent peer review panel and the USDOT OIG reviewed the study design, including the sample size.
Yes. FMCSA exceeded its goal. A total of 235 drivers enrolled in the study and provided data for up to 5 months.
Yes. The study team recruited drivers from fleets of all sizes (small, medium, and large) and operations (long-haul, regional, and short-haul) in various sectors of the industry (flatbed, refrigerated, tank, and dry-van).
Short-haul drivers were specified in the legislation that called for the study. The study team recruited short-haul drivers who may use either of the two restart provisions.
The legislation did not specify a gender requirement. The study team recruited a diverse sample of drivers, but has not and will not provide carrier or driver PII to FMCSA or other government agencies.
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