The Yellow Line, Metro's rail shuttle across the Potomac River, opened yesterday, drawing thousands of passengers and stirring praise from commuters, sightseers and government officials.

"We here in Northern Virginia have been waiting for this day for a long time," said Ellen M. Bozman, chairman of the Arlington County Board, during a ceremony in Crystal City. The Yellow Line, she added, will provide faster trips from parts of Northern Virginia to downtown Washington.

About 5,000 passengers rode on Yellow Line trains during the first four hours of service yesterday morning, according to estimates by Metro officials. The riders included families out for a weekend jaunt and others who found the Yellow Line a convenient shortcut. Metro offered free rides on Yellow Line trains during much of the day.

Phyllis Pierce took the Yellow Line to get from downtown Washington to her job as a sales clerk at a Northern Virginia department store. "It's a shortcut," she said. Until yesterday, she had relied on the Blue Line, a slower and more circuitous route.

Labeeb Abboud, a Georgetown University law student, rode on the Yellow Line to catch a plane at National Airport. "It should cut the time by 10 minutes or so," he said. "It's nice."

In addition to the ceremony at Crystal City, the line's opening was also marked by speeches in the Chinatown area of the District. A new subway entrance was unveiled in Chinatown at 7th and H streets NW. Its sign is embellished with Chinese characters and community leaders expressed hope that the new line would attract patrons to Chinatown's shops and restaurants.

"Please bring a healthy appetite and lots of money," exhorted Gene Lee, chairman of the Chinese Consolidated Benevolent Association, a position equivalent to mayor of Chinatown. A banner draped across H Street NW said, "Chinatown Welcomes Yellow Line."

Yellow Line trains travel between National Airport and Gallery Place, crossing the Potomac on a bridge east of the 14th Street automobile bridges. Passengers may transfer to the Blue and Orange lines at L'Enfant Plaza and to the Red Line at Gallery Place. A new Archives station opened at 7th Street and Pennsyvlania Avenue NW.

For many commuters, the Yellow Line will offer quicker rides than the Blue and Orange lines. A Blue Line trip between the Pentagon and L'Enfant Plaza takes 15 minutes, officials say. The Yellow Line provides a six-minute ride between the two stops.