A field test of the 34-hour restart provision of the new hours of service rule shows that the restrictions improve safety.

The test found that the provision, which requires drivers to take two successive periods off between 1 a.m. and 5 a.m. during their once-a-week restart, is more effective at combating fatigue than the earlier rule, said the Federal Motor Carrier Safety Administration.

The restart is the most controversial part of the new hours of service rule the agency implemented last July, and early reaction to the study was negative.

American Trucking Associations fought the restart in court and lost, then took the fight to Capitol Hill, enlisting legislators to propose bills that would suspend it pending an assessment by the Government Accountability Office. Those bills are awaiting action.

ATA’s contention has been that the provision cuts into productivity without improving safety. A key ATA complaint is that the agency did not have scientific justification for the restart restriction. The agency relied on a laboratory study when it should have tested those results in the field, ATA said.

At the association’s urging, Congress in the 2012 highway bill ordered the naturalistic field study that the agency released Thursday.

The study compared drivers who had one nighttime period of rest rather than the two required in the rule. It found that the former had more lapses of attention, were sleepier, particularly toward the end of their shifts, and showed more lane deviations.

“This new study confirms the science we used to make the hours-of-service rule more effective at preventing crashes that involve sleepy or drowsy truck drivers,” said agency chief Anne Ferro in a statement.

“For the small percentage of truckers that average up to 70 hours of work a week, two nights of rest is better for their safety and the safety of everyone on the road.”

Ferro has said that about 15% of all drivers fall into this category, and that the provision will prevent 1,400 crashes and save 19 lives a year.

The study, conducted in the first six months of last year,, involved 106 drivers from three companies, 100 men and six women, who covered almost 415,000 miles. The researchers, Hans Van Dongen and Daniel Mollicone of Washington State University, said this study is among the largest of its kind.

The drivers’ ages ranged from 24 to 69 years, and their experience ranged from less than a year to 39 years. Most (103) were employees of carriers in a variety of businesses, including intermodal, dedicated, flatbed, temperature control and truckload. The other three were owner-operators contracted to a carrier.

Their operations were roughly divided into three categories: local, regional and over-the-road.

The drivers tracked their hours with electronic logs and wore wrist monitors to gauge their wakefulness and sleep patterns through a variety of restart schedules. Fatigue levels were measured three times a day through a Psychomotor Vigilance Test, and the trucks were equipped with lane tracking systems.

The researchers said the field study bears out the results of the laboratory study FMCSA used to justify the restart rule.

“These results indicate that having at least two nighttime periods from 1 a.m. until 5 a.m. in the restart break helps to mitigate fatigue, providing evidence in support of the efficacy of the new restart rule,” they said.

‘Worthless,’ Says Hanna

Rep. Richard Hanna, R-N.Y., author of a House bill that would suspend the restart provision, panned the study and said it only underscores the need to suspend it.

“Considering the study arrived four months late, I expected a robust report, but the study is worthless,” he said in a statement.

He complained that the study looked at too small a sample and added that it does not address “perhaps the most serious issue that could change the entire outcome of the study – forcing truckers to work in the morning rush hour when roads are most congested and dangerous.”

“This half-baked study only underscores the need to legislatively delay the rule and have GAO conduct an independent analysis of the study so we can get a credible account of what this rule will truly mean for the safety of truckers, commuters and businesses.”

ATA’s response was more measured but still negative.

“We appreciate FMCSA releasing the results of its restart field study,” said Dave Osiecki, ATA executive vice president and chief of national advocacy. “However, in many respects this short report is lacking critical analyses on several important issues.”

Specifically, Osiecki said the study found “incrementally slower reaction times” among drivers with less rest and that FMCSA was cautious in suggesting how important these findings are.

He also said the study does not look at a second feature of the provision, the one limiting it to once-a-week use. And, like Hanna, he noted that the study does not look at the effect of the rule on traffic congestion. 

“While the study includes some findings favorable to certain portions of the new restart rule, the incomplete nature of the analysis and the lack of justification for the once-weekly use restriction is consistent with the flawed analyses that led the agency to make these changes in the first place,” Osiecki said.