The Metro subway system will open a 9.1-mile Orange Line extension to Vienna at 8 a.m. today. Free one-way rides will be available until 4 p.m. at four new stations along the median of Rte. I-66.

Ceremonies are scheduled at 9 a.m. at the East Falls Church station at Sycamore Street, 10 a.m. at West Falls Church at Leesburg Pike, 11 a.m. at Dunn Loring at Gallows Road and noon at Vienna at Nutley Street. Community groups have planned food and book sales, balloon rides, tours, music and other entertainment.

Parking is free at all four stations on weekends. On weekdays, parking will cost $1 at Vienna and Dunn Loring and $1.25 at East and West Falls Church.

Fairfax City's bus system, called CUE, will offer free rides from the city to the Vienna station, starting today. In July, CUE will charge a 25-cent fare.

Changes in Metrobus routes to serve the new stations are scheduled to take effect June 22. A new Tysons Shuttle van, sponsored by the Northern Virginia Transportation Commission, is to begin service June 16, connecting the West Falls Church station with the Tysons Corner area. Washington Flyer bus service linking West Falls Church with Dulles International Airport will start June 22.

Metro officials have urged commuters who plan to use the new stations next week to buy Farecards in advance to avoid delays on Monday. A rush-hour trip from Vienna to the Metro Center station in downtown Washington will cost $2.30. From West Falls Church, the rush-hour fare to Metro Center is $1.70. At other times, both trips will cost $1.10.