Trailways Inc. asked the Interstate Commerce Commission yesterday to forbid Greyhound Lines Inc. from operating any new intercity bus routes until the ICC has studied the impact of new route awards on competition.

The filing by Trailways is the latest in a long-running battle between the giants of the intercity bus business in which Trailways has charged that Greyhound seeks to stifle competition.

"The closest analogy to Greyhound's power in the bus industry is presented by the American Telephone and Telegraph Co.'s historic dominance of the telecommunications industry," Trailways said in its filing.

The petition comes just as the Bus Regulatory Reform Act is taking effect and before its full impact is known to the industry and the 375 million passengers--more than use the scheduled airlines--who depend on buses annually for transportation.

Trailways said in its filing that a recent ruling by the U.S. Court of Appeals here compels the ICC to revoke Greyhound's operating authority for service already started in Little Rock, conduct a thorough examination of the intercity bus market and deny new Greyhound operating requests until that examination is completed.

The court order, subsequently upheld by the Supreme Court, told the ICC to restudy the grant of rights to Greyhound in light of "the systemwide impact that a grant of Greyhound's application would have on Trailways Inc., its subsidiaries and the bus transportation industry in general."

The ICC is studying Trailways' contention and the court ruling, an official there said, as well as the impact of the bus deregulation act on the issue. That act generally makes it much easier for a bus company to operate where it wishes and preempts many state regulations.

Greyhound officials had no comment.