WASHINGTON — The Bush administration yesterday permanently relaxed rules governing how many hours each day truckers may spend behind the wheel, issuing regulations that would allow drivers to continue spending 11 hours a day on the road in a move denounced by consumer-safety advocates.

The Transportation Department said the new rules would improve highway safety because they also shorten a trucker's overall workday and increase required rest periods between shifts. But consumer advocates said the rules were a giveaway to the trucking industry and a step backward.

The rules are similar to those adopted by the Bush administration in 2003, which were challenged by safety advocates who won a federal court ruling in July setting them aside. The Federal Motor Carrier Safety Administration, which regulates trucking, justified yesterday's action reinstating the rules by pointing to new research.

"The court did not require us to write a stricter rule," said the agency's administrator, Annette Sandberg, who argued that the agency lost the case on technical grounds for not having scientific justifications. Since then, she said, the agency conducted more research, outfitting rigs with video cameras, motion detectors and instrumentation to monitor driver fatigue, sleep and hours of work.

The rules, which take effect Oct. 1, allow 11 hours of driving in a single stretch, up from the 10-hour limit that had been in effect until 2003. The new regulations would allow truckers to drive up to 77 hours a week, up from 60.

The rules shorten the overall workday from 15 hours to 14 and require truckers with sleeper berths to take longer breaks by spending at least eight continuous hours in bed. The old rules allowed rest periods to be split up.

The rules also largely deregulate short-haul truckers, eliminating the requirement that they keep records of how many hours they work.

Keep on trucking


New: Allow 77 hours driving per week, 11 hours in a single stretch, 14-hour workday; requires spending at least eight continuous hours in sleeper berth.

Old: 60-hour week, 10-hour limit, 15-hour workday; rest periods could be split up.

Also: Largely deregulates short-haul truckers, eliminates requirement of keeping records of hours worked.

Takes effect: Oct.1

The new highway bill signed by President Bush last week also exempted utility-company drivers, movie-and-television-production drivers, drivers carrying livestock, and those hauling animal feed from the law.

The issue has pitted the trucking industry and retailers such as Wal-Mart against unions and safety advocates who said the rules would make highways more hazardous.

"It reduces weekly off-duty time for the most-exhausted drivers [truckers who drive the maximum number of allowable hours] and significantly weakens safety requirements for short-haul drivers," said Joan Claybrook, president of the consumer group Public Citizen, one of the groups that sued the administration last year.

"Some greedy employers are trying to squeeze drivers to enrich their bottom line at the expense of public safety on America's highways," said James Hoffa, head of the Teamsters union.

Safety advocates and the Teamsters were particularly critical of the changes applying to short-haul drivers such as those who work for UPS and FedEx.

The Transportation Department said trucker fatigue was to blame only in 5.5 percent of all fatal collisions involving trucks.