Dulles Toll Road commuters will pay more starting Jan. 1 to help pay off Metro's $6 billion Dulles Rail line.

For cars, the cost of a one-way trip will go up 50 cents for cars, from $2.25 to $2.75. That will run $1,430 a year -- $260 more than in 2012 -- for commuters who rely on the road daily.

The rates will jump again in 2014, to $3.50, as the agency in charge of the toll road -- the Metropolitan Washington Airports Authority --uses the toll revenue to pay for 75 percent of the cost of building the Silver Line from East Falls Church into Loudoun County. Rail line opponents and commuters have protested the toll increases, warning they are likely to skyrocket in the future, to $9 round-trip by 2015 and even higher later.

"People who can't afford to pay will be off the road. So some will actually see that as a benefit," said David LaRock, an opponent of the rail line. "What we've heard from people is that this is going to be a budget-buster. I've heard from some people that they're going to sell their homes and move out of the area."

Airport officials said the tolls are the only available way to finance the rail line if Virginia or the federal government can't contribute more to the project.

"After considering public comments received at the toll rate hearings ... the 2013 and 2014 toll adjustments were determined necessary to help pay for Phase 1 Silver Line construction costs," airports authority spokeswoman Kimberly Gibbs said in a statement.

Sen. Dick Black, R-Leesburg, is lobbying Gov. Bob McDonnell for an extra $200 million for the Silver Line, and Virginia Democrats are also lining up behind the project.

"It's amazing to me that we would spend money on this Route 460 fiasco [in Southern Virginia] and not put money towards what is going to be the most critical transportation corridor probably in the commonwealth over the next 20 years," said Sen. Chap Petersen, D-Fairfax.