This post has been updated. (Yes, we realized it’s “Sept. 11, 2001,” rather than “Sept. 11, 2011.”)

A motorcycle procession honoring victims of the Sept. 11, 2001, terrorist attacks could impact traffic in Northern Virginia on Friday afternoon and in Maryland on Saturday morning.

The ride, organized by the nonprofit group America’s 911 Foundation, is traveling from Somserset, Penn., to Arlington on Friday before heading to New York on Saturday morning.

This procession will close a part of the eastbound Dulles Access Highway, the toll road near exit 9 and two ramps between approximately 2 and 2:30 p.m., said Kimberly Gibbs, spokeswoman for the Metropolitan Washington Airports Authority, which operates the Dulles airport. [3 P.M.: The Dulles Toll Road and Access Highway have fully reopened.]

The bus ramp near exit 14 (for Hunter Mill Road) and the ramp from Route 123 onto the eastbound connector road will also be closed for roughly the same period, she said.

The exact timing depends on traffic and weather, so watch for issues shortly before and after.

Last year, more than 1,800 riders were expected. This year, they are expecting closer to 500 bikes, according to MWAA spokeswoman Kimberly Gibbs. Fewer bikes should keep it from creating major traffic nightmares.

The schedule calls for riders to stop for lunch in Hagerstown on Friday afternoon. After lunch, riders will take I-70 East toward Frederick before heading south on U.S. 15 through Leesburg. King Street in Leesburg will briefly be closed to traffic during the procession.

After that, the riders will pass through Dulles before merging onto eastbound I-66 heading to Washington. The procession will exit onto southbound VA 110 and move into Pentagon City, the final destination for the night. Watch for potential closures and issues on eastbound I-66 this afternoon.

The riders are leaving the Pentagon at 7:15 a.m. Saturday and taking I-395 north to DC-295 north and onto I-895 north. After traveling through Baltimore’s Harbor Tunnel, they will get onto I-95 north. So you should also expect potential issues if you’re heading north on Saturday morning.