Even as a federal court was recently upholding most of the hours of service rules, the Federal Motor Carrier Safety Administration has been working on a field study of the 34-hour restart that could influence that provision in the future, and there's a move on Capitol Hill to force the agency to return to the old rules.

Congress ordered the study in last year’s highway bill, at the insistence of the American Trucking Associations,, which said the agency should confirm in the field the finding from a laboratory study that daytime sleep is not as restorative as nighttime sleep.

That finding is the scientific basis for the requirement that a driver take two periods off between 1 a.m. and 5 a.m. during his 34-hour restart, and it figured prominently in the court’s decision to uphold the provision.

It remains to be seen if the data from the field study will be persuasive enough for the agency to reconsider its approach to the restart.

Data collection for the study was finished in July and the final report is expected later this year, said agency spokesperson Marissa Padilla.

Meanwhile, there is a move in the House of Representatives to cut off funding for implementation or enforcement of the new hours and return to the old rule.

An attempt by Rep. Richard Hanna, R-N.Y., and several others to attach the amendment to transportation funding legislation failed when House leaders withdrew the bill.

But Hanna will pursue the amendment, said Renee Gamela, his communications director.

“He’s been discussing the amendment with colleagues and we’re confident it would have strong, bipartisan support when it comes up,” Gamela said.

The amendment is supported by 16 trucking and shipping interests, including ATA, OOIDA and UPS, as well as the Transportation Intermediaries Association, the National Retail Federation and the National Grocers Association.

Hanna, joined by Reps. Tom Rice, R-S.C., Trey Radel, R-Fla., and Todd Rokita, R-Ind., said in a Dear Colleague letter that the new rule decreases driver flexibility and raises costs – complaints that have been aired by all of the industry interests.