BLACKSBURG, Va. — It makes no statistical difference to safety whether a driver is on the road for 10 or 11 hours, a new study to evaluate the safety impact of U.S. hours-of-service regulations has revealed.

The study, which reiterates some past research on the subject, effectively puts a wet blanket on the claims by special interest groups that new HOS rules lead to tired truckers and increase the likelihood of accidents on the highways.

The rules allow truckers to be behind the wheel up to 11 hours — up from the 10 hour maximum before 1994. The news rules also require a 10 consecutive hour break versus eight hours previously.

Virginia Tech’s Transportation Institute conducted the study, which was funded by the Federal Motor Carrier Safety Administration (FMCSA) Office of Analysis, Research and Technology.

The theory that drivers are more likely to cause a crash in the
11th hour on the road versus any other hour is not supported.

The study mainly analyzed risk as a function of driving hours 1 through 11 and examined how critical incidents may vary as a function of driving shift and time of day.

A recent webinar presented by the FMCSA provided an in-depth review of the results by VTTI’s director, Dr. Richard Hanowski.

Specifically, the results from the analysis on critical-incident relative frequency generally showed no statistical difference in the hours between the second through 11th driving-hours.

“That is, the results of this study do not support the hypothesis that there is an increased risk resulting from commercial motor vehicle drivers driving in the 11th driving-hour as compared to the 10th driving-hour, or any hour,” VTTI stated in a press release.

“In fact, a significant spike in the rate of critical incidents was found during the 1st driving-hour and was found across many different analyses.”

Additional analyses found a strong time-of-day effect, which, upon closer examination, appeared to have resulted from hour-by-hour traffic density variations.

The study authors estimate that exposure to heavy traffic conditions, and possibly sleep inertia and an increase in complex driving situations that may be typical in the first driving-hour, may have influenced the increase in critical-incidents recorded in this time period.