The Dulles Access Road's median hosts the Silver Line of the Washington Metro between the airport and Tysons.

As this road is exclusively used for entering and exiting Dulles Airport, there are no general-access exits from the westbound lanes, and no general-access entrances to the eastbound lanes, with the exception of gated slip ramps to and from the toll road that buses and emergency vehicles can use, and it is free of charge to use.

This ramp bypasses congestion associated with the main toll plaza, where traffic from Dulles Airport attempts to exit at Route 7.

The toll road begins just inside the Capital Beltway near West Falls Church at a connector to Interstate 66 to Washington, D.C., travels westward through Fairfax County past Dulles, and terminates at the entrance to the Dulles Greenway, a privately owned toll road that is a continuation of Route 267.

Officially, the road is named the Omer L. Hirst – Adelard L. Brault Expressway, in honor of two Virginia state legislators.

In response, Congress (which did not have direct control over the highway) passed special legislation prohibiting the imposition of HOV restrictions on the route.

[12] However, unlike the third lane, officials did not allow non-HOV use at the end of construction in 1998, and avoided a repeat of the controversy.

However, Rep. Frank Wolf again threatened to pass federal legislation prohibiting the fourth lane to be limited to HOV traffic.

[14] In 2005, five companies submitted proposals to VDOT to privatize the toll road which included payments to Virginia that could be used for transportation.

In response MWAA made its own proposal to take over operation of the toll road from VDOT, assuming associated debts, and commit to building a rapid transit line in the median.

The 2013 and 2014 toll increases primarily help pay for Phase 1 Silver Line Metrorail construction costs.

[22] HOV-2 restrictions are in effect during weekday rush hours, 6:30 to 9:00 am eastbound and 4:00 to 6:30 pm westbound, limiting the left lane to vehicles with two or more passengers between State Route 28 and the main toll plaza.

Traditional hybrid vehicles such as the Toyota Prius that do not plug in are no longer exempt from HOV rules.

Vehicles with 2 or more people may switch their E-ZPass Flex into HOV mode to avoid being charged for tolls.

The northbound side of the freeway leads directly onto US-15 North at its termination, thus forming a continuous route towards Frederick, MD and beyond.

[28] The road was envisioned as early as the 1970s, when new residents were attracted to Loudoun County because of the relatively low cost of real estate.

[31] The road was completed and opened in 1995, but the original owners defaulted on its loan due to lower than projected use.

[32] It receives no public funds, was built with no subsidies, and is policed at its own expense, competing as a wholly private enterprise with the state-built and -maintained roads.