Northern Virginia Del. Jim LeMunyon filed legislation that would require any future fare increases on the Dulles Toll Road to be approved by the Fairfax and Loudoun county supervisors, but experts say the bill could threaten the multibillion-dollar extension of Metro service to Washington Dulles International Airport. LeMunyon, R-Chantilly, said he is looking to the General Assembly for help because he’s concerned that plans to increase the tolls on the road tenfold by 2028 could divert more drivers from the toll road and onto already congested highways like Interstate 66 and Route 7. Since 2009, traffic on the toll road dropped 4.4 percent as tolls rose.

The toll at the main toll plaza jumped 25 cents to $1.25 on Saturday, and officials estimate the new rate will raise about $97.1 million in 2011, an 11 percent increase over 2010. Ramp fares remain 75 cents.