Drivers on the Dulles Toll Road are likely to pay more to travel the roadway starting next year.

Members of the Metropolitan Washington Airports Authority’s board of directors were briefed Wednesday on the process for raising tolls on the 14-mile stretch.

Since 2014, most drivers have been paying $3.50 to drive the toll road — $2.50 at the main toll plaza and $1 at on/off ramps. The next projected increase is expected to boost tolls to $4.75 for the main toll plaza and one ramp transaction. According to financial documents provided by MWAA, that rate is expected to remain in place through 2022 and increase again in 2023 to $6. By 2043, tolls could increase to $11.25 (see chart below).

MWAA manages the roadway, and revenue generated from tolls is being used in part to pay for construction of the Silver Line rail project. Toll road users are funding nearly half of the cost of the $5.8 billion rail line. The second phase, which is under construction, will extend Metro service to Dulles International Airport and into Loudoun County. The first phase, which included four stations in Tysons and one in Reston, opened in July 2014. The second phase is expected to open in 2020.

Though Virginia has become a leader in using toll revenue to pay for transit improvements, increases on the Dulles Toll Road are particularly sensitive because many residents think it’s unfair to tax drivers to pay for the cost of building a new Metro line. At least two lawsuits have been filed challenging MWAA’s authority to use toll road revenue to pay for the Silver Line. However, none has been successful at ending the practice.

Tolls went up five times between 2010 and 2014 before stabilizing after Virginia contributed $150 million to the second phase of the rail project.

MWAA recently began work on a $23.4 million upgrade to the current electronic toll system. The new equipment offers the possibility that drivers could be charged different rates based on traffic conditions and the time of day they travel. Similar systems are in place throughout Northern Virginia, including Interstates 495, 95 and the 66 Express Lanes. The most recent example is I-66 inside the Capital Beltway, where solo weekday rush-hour drivers traveling in the peak direction pay tolls based on traffic and demand.

However, MWAA chief executive Jack Potter on Wednesday was quick to say that the authority is not considering variable tolling as part of a possible increase in 2019.

Public hearings are likely to be held this summer, and the board could adopt the new rates at its October board meeting.