The price of a round-trip ride on the Dulles Toll Road could rise by $1 next year and go as high as $9 by 2015.

The airports authority in charge of the Dulles Toll Road gave preliminary approval to toll increases Wednesday as part of its effort to fund Metro's $6 billion Silver Line to Washington Dulles International Airport.

The Metropolitan Washington Airports Authority signed off on a 50-cent increase for one-way tolls next year, up from $2.25 to $2.75. Tolls would rise to as much as $3.50 in 2014 and $4.50 in 2015 under the plan.

An earlier estimate from the authority suggested tolls could rise to as much as $4.50 next year. But the increases will be less because Virginia agreed to contribute $150 million toward the project's costs, offsetting the need for higher tolls, officials said.

Authority members said the increases shouldn't surprise drivers, though they still expect opposition.

"People are aware ... that tolls are going to have to go up," said airports board member Bob Brown. But "I think we will get some static."

The authority will hold public meetings on the toll rates before taking a final vote in November. Higher rates would take effect Jan. 1.

The airports authority on Wednesday also refused to give a new Virginia appointee, McLean businesswoman Caren Merrick, a seat on the board. Merrick was appointed after Gov. Bob McDonnell ousted union executive Dennis Martire, whom McDonnell said took lavish trips on the authority's dime and had a potential conflict of interest when it came to union labor.

Virginia Secretary of Transportation Sean Connaughton said the state "would take every action" to seat Merrick.

"The MWAA board does not have the legal authority to appoint, remove or deny the seating of members," Connaughton said. "The action it took today was clearly illegal."

The ousted Martire also was prevented from taking a seat with the board. He said he should be allowed to continue serving while courts review the case.

"I believe that the governor's actions are contrary to law," he said in a statement. "There is no legitimate cause for me to be removed. ... MWAA's choice to limit my participation as a board member is wrong."