Correction: An earlier version of this article suggested drivers could be charged up to $4.50 to travel to Dulles International Airport. In fact, most airport visitors use the adjacent Dulles Access Highway, which does not charge a toll. This version has been updated.

The Dulles Toll Road is about to get more expensive — the only question is by how much. The toll is likely to increase by 50 cents at the start of 2013 and could increase almost an additional $2 in the next two years.

By 2015, a one-way trip from the Capital Beltway to Washington Dulles International Airport could cost as much as $4.50 — double the current one-way toll of $2.25 for drivers who skip the Dulles Access Highway.

The Metropolitan Washington Airports Authority, which oversees the toll road, will hold a series of hearing through October to present the proposed toll increases to the public. While MWAA officials have said they welcome feedback, they say it’s unlikely that anyone will persuade them not to raise the tolls.

“I don’t want to mislead anyone. Tolls have to go up,” said Andrew Rountree, MWAA’s chief financial officer. “There’s a minimum level of toll increase that really has to occur in order for the board to meet its responsibilities.”

The proposed toll increases are meant to address one responsibility in particular: Metro’s Silver Line, which will run from Washington to Dulles and on into Loudoun County. While some of the new revenue will be used to service MWAA’s existing debt, the main reason for the increase is to help fund the Silver Line’s construction.

“That has always been the airport’s plan,” Rountree said, “ever since we said that we would take over the toll road and take responsibility for the Metro project.”

The dates of the public meetings have not been set, but MWAA spokesman Rob Yingling said they will probably take place in Tysons Corner, Reston and eastern Loudoun.

While MWAA officials say a higher toll is necessary to fund construction of the Silver Line, some question whether tolls should be used to pay for transit at all.

“Whether it’s the Dulles Toll Road or any other toll road in Virginia, tolls should be used to build and maintain the road that’s tolled and not used as a cash cow for other purposes,” Del. Jim LeMunyon (R-Fairfax/Loudoun) said Monday at a hearing of the state Transportation Accountability Commission.

Rountree said his staff will present the results of the public discussions to MWAA’s finance and Dulles corridor committees in October. At that point, one or both of the committees will make a formal recommendation to MWAA’s board. The board, in turn, will vote on the proposal in November.