WASHINGTON, D.C. — Large commercial vehicles, including school buses, would have to be equipped with speed limiters under a proposal from federal regulators.

The proposed rulemaking, issued by the National Highway Traffic Safety Administration (NHTSA) and the Federal Motor Carrier Safety Administration (FMCSA), would require the speed-limiting devices on newly manufactured trucks, buses, and multi-purpose passenger vehicles with a gross vehicle weight rating of more than 26,000 pounds.

The devices would have to be set to a maximum speed, which would be specified in a final rule if the agencies move forward with the rulemaking.

NHTSA and FMCSA, both divisions of the U.S. Department of Transportation, said that the measure could save lives and cut an estimated $1.1 billion in fuel costs per year.

“There are significant safety benefits to this proposed rulemaking,” Transportation Secretary Anthony Foxx said. “In addition to saving lives, the projected fuel and emissions savings make this proposal a win for safety, energy conservation, and our environment.”

The proposal discusses the benefits of setting the maximum speed at 60, 65, and 68 miles per hour, but the agencies said that they would consider other speeds based on public input.

“This is basic physics,” NHTSA Administrator Mark Rosekind said. “Even small increases in speed have large effects on the force of impact. Setting the speed limit on heavy vehicles makes sense for safety and the environment.”

Under the proposal, motor carriers operating commercial vehicles in interstate commerce would be responsible for maintaining the speed-limiting devices at or below the designated speed for the service life of the vehicle.

The proposed rulemaking can be viewed here. Comments on the proposal can be submitted at www.regulations.gov.