Continental Trailways has asked the federal government to require all interstate commercial vehicles to be equipped with speed governors that would limit them to 55 miles per hour.

Trailways, the Dallas-based intercity bus company, already has started putting the devices on its buses and has been advised by the National Highway Traffic Safety Administration that the agency will seek public comment on the firm's proposed rule requiring the governors on all interstate commercial vehicles.

"The law of the land is 55 miles per hour" said Trailways President Kevin J. Murphy, explaining the reason for the bus company's petition. "... But when the biggest killer of people outside disease is the automobile and other vehicles and you're allowing trucks and cars to roll down the highway with fuzz-busters and CBs and break the law, that's just crazy."

The Trailways chief said the governors will prevent deadly accidents and save fuel. Murphy maintains that all trucks and buses can be equipped with governors, and it is the only way to make drivers comply with the national speed limit.

But while most commercial interstate truck and bus companies say they support the 55 mph speed limit and enforce it with their drivers, they contend there are several technical and safety problems with the Trailways proposal.

"There is some equipment out today that will work on the older Detroit engines," said Larry Strawborn, director of engineering for the American Trucking Associations. "The equipment will limit speeds, but on the new engines, it won't work."

Strawborn said the ATA and the Department of Transportation are studying the speed-governor question but explained there is not a device on the market that will effectively limit speeds and is still safe. Many devices, he said, will cut the engines off at 56 mph, leaving the-driver with no power.

Beyond the mechanical shortcomings of the devices on the market, truck and bus companies say it is too easy for drivers to tamper with the governors to make their vehicle go faster.

The Trailways proposal will face additional opposition from bus and truck drivers. When the bus company announced last May it would be putting governors on its buses, loud voices of protest arose from its own drivers. The drivers contend the governors make the buses unsafe, leaving them with no power to maneuver in an emergency.