The effort to suspend the hours of service restart provision will come to a head on the Senate floor this week, possibly this afternoon.

Trucking companies that want the restart suspended while the Federal Motor Carrier Safety Administration studies its effects are pressing to keep that provision in the Senate’s transportation appropriations bill.

On the other side are other carriers allied with safety advocates and the safety enforcement community. They want to keep the current restart in place while the agency conducts the study.

The Senate is scheduled to begin debate today on the appropriations bill containing the amendment that would suspend the restart. It may not reach the restart issue before close of business, however.

American Trucking Associations is leading the push to preserve the amendment championed by Sen. Susan Collins, R-Maine, that would suspend the current restart.

ATA is hosting a call-in this morning for trucking executives to discuss how the current restart provision is affecting their business. The association says the restart cuts productivity, harms drivers and does not improve safety.

The opposing side has scheduled a call-in for this afternoon.

Advocates for Highway and Auto Safety is hosting a call that will include Steve Williams, chairman and CEO of Maverick USA, in support of a move by Sens. Cory Booker, D-N.J., and Richard Blumenthal, D-Conn., to remove the Collins amendment.

Williams is also chairman of The Trucking Alliance, a group of a half-dozen carriers that would prefer to keep the restart as it is while FMCSA completes the study.

Also on the call will be Steve Keppler, executive director of the Commercial Vehicle Safety Alliance, which Monday posted a statement opposing the suspension.

“Legislating changes to the HOS rules now, not even a year since becoming effective, creates significant uniformity and consistency problems across the country,” said Keppler in the statement.

The Collins amendment will create problems for state enforcement of the hours of service rules, he said.

“While there certainly have been legitimate concerns raised by the regulated industry on the impacts of the new rules, the Administrative Procedures Act is there for a reason and it needs to be followed,” he said.

“The importance of these rules cannot be understated, and to make changes without the appropriate analysis of their impacts or without providing appropriate due process and adequate time to implement them is irresponsible policy.”

At issue is the provision of the 2013 hours of service rule that requires drivers to take two periods off between 1 a.m. and 5 a.m. during their 34-hour restart, and limits use of the restart to once a week.

ATA won the first round with a lopsided 21 to 9 vote for the Collins amendment during markup of the Senate Appropriations Committee bill. Collins argued successfully that the provision has had unintended consequences by forcing some carriers to put trucks on the road during morning rush hour, increasing traffic congestion and risk.

Her amendment in effect suspends the two-night rest requirement and once-a-week limitation and re-imposes the pre-2013 restart, which does not contain these restrictions.

It also requires FMCSA to study the restart by comparing the work schedules and fatigue of drivers who operate under the old restart and the new one.

The Senate’s decision this week will not necessarily settle the issue. The House appropriations bill does not contain a suspension provision, and the two chambers will have to agree on a final policy before the matter is settled.