Research Project

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Crash Risks by Commercial Motor Vehicle (CMV) Driver Schedules, Phase II


To collect hours-of-service (HOS) and crash data to analyze (1) how HOS provisions are being used and (2) the impact of driver schedules on crash risk.


The Federal Motor Carrier Safety Administration (FMCSA) conducted a study that evaluated the impact of driving hours, working hours, and breaks on safety-critical events (SCEs) (Blanco, M., et. al., 2011). The study included 99 drivers who drove a total of 700,000 miles, during which naturalistic driving data, including video, were collected. That study found that (1) as the number of driving hours increased, so did the number of SCEs, (2) when evaluating the interaction between driving and non-driving work, a much greater time-on-task effect emerges for drivers driving late in their work shift, and (3) driving breaks decrease risk in the hour after a break.


This study will collect additional data to answer important questions related to driver schedules and how these factors impact overall driver performance and fatigue. This study is being completed in phases. In Phase I, the research team collected HOS and crash data. In Phase II, the research team will use the data collected in Phase I to analyze crash risk as it relates to various aspects of the HOS provisions. This study will analyze:
  • Relative crash risk by hour of driving.
  • Relative crash risk by hour of driving per week.
  • Relative crash risk of driving breaks.
  • Relative crash risk as a function of recovery periods. 
  • How each of the HOS provisions is being used.
In addition, the study will design, develop, and deliver a database so that the data collected in this study can be used for future research efforts.


  • An analysis of crash risk by driving hour, driving breaks and recovery periods.
  • A database of the HOS and crash data for use in future research efforts.



October 2017: Kick-off meeting.
December 2018: Finalize user website to collect ELD and crash data.
January 2019: Recruit carriers and begin data collection.
June 2021: Conduct analysis with all collected data.
September 2021: Final report and briefing.


FY17 Funding: $1,498,970

Project Manager:

For more information, contact Theresa Hallquist of the Research Division at (202) 366-1064 or


Virginia Tech Transportation Institute
Updated: Friday, May 25, 2018
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