Due to heavy commuter traffic, I-66 features a variety of high-occupancy vehicle (HOV) restrictions.
Between US 15 in Haymarket, Virginia and the Capital Beltway, the left lane on eastbound I-66 is reserved for vehicles with two or more occupants (HOV-2 traffic) from 5:30 to 9:30 a.m. on weekdays, and the left lane on westbound I-66 is reserved for HOV-2 traffic from 3:00 to 7:00 p.m on weekdays.

Between the Beltway and the Theodore Roosevelt Bridge, the eastbound (inbound) roadway is a HOT road from 5:30 to 9:30 a.m., and the westbound (outbound) roadway is a HOT road from 3:00 to 7:00 p.m. E-ZPass is required for all vehicles except motorcycles, including Dulles Airport users.
I-66 is free during those times for HOV-2 drivers (HOV-3 in 2022) with an E-ZPass Flex and for motorcycles.
Other drivers must pay a toll which can be almost $50 at peak times.
Due to heavy commuter traffic, I-66 features a variety of high-occupancy vehicle (HOV) restrictions. Between US 15 in Haymarket, Virginia and the Capital Beltway, the left lane on eastbound I-66 is reserved for vehicles with two or more occupants (HOV-2 traffic) from 5:30 to 9:30 a.m. on weekdays, and the left lane on westbound I-66 is reserved for HOV-2 traffic from 3:00 to 7:00 p.m on weekdays.
Between the Beltway and the Theodore Roosevelt Bridge, the eastbound (inbound) roadway is a HOT road from 5:30 to 9:30 a.m., and the westbound (outbound) roadway is a HOT road from 3:00 to 7:00 p.m. E-ZPass is required for all vehicles except motorcycles, including Dulles Airport users. I-66 is free during those times for HOV-2 drivers (HOV-3 in 2022) with an E-ZPass Flex and for motorcycles. Other drivers must pay a toll which can be almost $50 at peak times.
Interstate 66