Several conservation groups have filed suit to block plans to widen all 325 miles of Interstate 81 in Virginia.
The lawsuit was filed against the Federal Highway Administration in U.S. District Court to halt plans to widen I-81 and charge tolls on it.
The Commonwealth Transportation Board last year authorized a plan that calls for more lanes on certain stretches of the interstate to make it easier for trucks to climb hills.
But Megan Gallagher of the Shenandoah Valley Network, one of the groups that filed the lawsuit, said the Virginia Department of Transportation still insists that four new lanes are needed along 69 percent of the interstate.
VDOT officials say the agency only is pursuing plans authorized by the transportation board.