WASHINGTON (Reuters) - Trucks and buses in the United States may have to be equipped with devices to limit their speed under a proposed rule issued on Friday by the U.S. Transportation Department which said the move could save both lives and fuel.

A bus passes in front of the 446-foot-high (136-meter-high) Margaret Hunt Hill Bridge in Dallas, Texas April 3, 2012. REUTERS/Mike Stone

The department will weigh setting speed limits at 60, 65 or 68 miles per hour for heavy commercial vehicles, but said it will consider other speeds based on comments from the public.

Speed limits on interstate highways vary across the United States, with some states allowing vehicles to drive as fast as 85 mph (137 km per hour), though many states have lower maximum speeds for trucks.

“There are significant safety benefits to this proposed rulemaking,” Transportation Secretary Anthony Foxx said in a statement.

“In addition to saving lives, the projected fuel and emissions savings make this proposal a win for safety, energy conservation, and our environment.”

The American Trucking Association, a trade group for the industry, praised the proposal, and noted that it had petitioned the National Highway Traffic Safety Administration in 2006 to require speed limiting technology. The group has endorsed a national speed limit of 65 mph (105 kph) for trucks.

“Carriers who already voluntarily use speed limiters have found significant safety, as well as fuel efficiency and equipment lifespan benefits with little to no negative impact on productivity,” ATA President Chris Spear said in a statement. “We will be carefully reviewing and commenting upon today’s proposal.”

However, the Owner-Operator Independent Drivers Association, a group that represents independent truckers and small business operators, said the proposed rules would take control out of the hands of drivers preventing them from speeding up to avoid danger, and create unsafe disparities in the speed of vehicles on highways.

Under the long-delayed proposal, all new U.S. trucks and buses weighing more than 26,000 pounds (11,793 kg) would need to be equipped with a speed-limiting device.

The department said the maximum allowable speed would be decided after the agency receives public input. Publication of the proposal kicks off a 60-day comment period.

It said both vehicle manufacturers and the companies that purchase and operate the vehicles would be subject to the rule.

Representatives of truck makers and large truck fleets contacted Friday did not comment or said they were still studying the proposal.