Field Study on the Efficacy of the New Restart Provision for Hours of Service [Final Report]
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Summary
This report details a naturalistic field study conducted by the Federal Motor Carrier Safety Administration (FMCSA) to evaluate the efficacy of the new Hours of Service (HOS) restart provision. The regulation, mandated by Congress through the Moving Ahead for Progress in the 21st Century Act (MAP-21), requires commercial motor vehicle (CMV) drivers to include at least two nighttime periods (1 a.m. to 5 a.m.) in their 34-hour restart breaks to ensure adequate sleep recuperation. The study aimed to determine if this requirement effectively mitigates driver fatigue compared to restart breaks containing only one nighttime period. The research team conducted the study between January and July 2013, involving 106 CMV drivers across three carriers. Participants were monitored during two duty cycles and the intervening restart break, providing 1,260 days of data and over 414,000 miles of driving. Researchers utilized wrist activity monitors to track sleep/wake patterns, smartphone-based Psychomotor Vigilance Tests (PVT) and subjective sleepiness scales to measure fatigue, and truck-mounted data acquisition systems to record lane deviation. The study design compared fatigue outcomes in duty cycles preceded by restart breaks with only one nighttime period against those preceded by breaks with two or more nighttime periods. The results demonstrated that drivers with restart breaks containing only one nighttime period exhibited significantly higher levels of fatigue. Specifically, these drivers showed more lapses of attention on the PVT, greater subjective sleepiness, and increased variability in lateral lane position, particularly during nighttime hours. Additionally, these drivers displayed nighttime-oriented duty and driving patterns with daytime-oriented sleep, indicating insufficient recovery. In contrast, drivers who had restart breaks with two or more nighttime periods reverted to a predominantly nighttime sleep schedule and showed significantly less fatigue. The data confirmed that the new rule primarily affects nighttime drivers, who are at the greatest risk for fatigue, and that extending the break to include a second biological night provides greater opportunity for sleep recuperation. The study concludes that the new restart rule is effective in mitigating driver fatigue by ensuring drivers have at least two nighttime periods for sleep recovery. These findings support the regulatory change, suggesting that the provision helps improve safety on U.S. roads by reducing the risk of fatigue-related crashes. The results align with prior laboratory studies, providing robust evidence that circadian-aligned rest periods are critical for maintaining performance in commercial driving operations.
Key finding
Drivers showed greater levels of objectively and subjectively measured fatigue and increased lane deviation during duty cycles preceded by a restart break with only one nighttime period compared to those preceded by a restart break with two or more nighttime periods.
Methodology
naturalistic
Sample size: 106
Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | rosap | — | — | 2 | 2026-05-23 |
| archive | success | — | — | — | 1 | 2026-05-23 |
| extract | success | cached | — | — | 2 | 2026-06-10 |
| clean | success | — | — | — | 1 | 2026-06-01 |
| chunk | success | — | — | — | 1 | 2026-06-01 |
| embed | success | — | — | — | 1 | 2026-06-02 |
| enrich | success | — | — | — | 1 | 2026-05-23 |
| promote | success | — | — | — | 1 | 2026-05-23 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 3 | 2026-06-10 |
| tag | success | vector_similarity | — | — | 19 | 2026-06-11 |
| verify | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
Topics
Ranked by relevance to this paper. Hover a topic for its definition.
- truck driver fatigue
- hours of service
- shift work driving
- time on task
- circadian factors
- sleep deprivation
Information type
What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).
- Empirical Findings: physiological data, behavioral performance data