The Metro transit authority, responding to widespread complaints from subway riders, is taking steps to reduce confusion and help passengers figure out which train to board at National Airport and other stations served by the recently opened Yellow Line.

Erroneous signs posted at subway platforms are being corrected, officials said yesterday. Announcements of train departures are being made more frequently and audibly at the National Airport station, they added, and rush-hour trains have been ordered to stop closer to the platform's entrance.

"We're going to do everything we can to get the signs and the announcements straight and to help people get where they want to go as easily as possible," said Theodore G. Weigle, Metro's assistant general manager for transit operations.

Since Yellow Line service began April 30, rail patrons and politicians have complained about inadequate signs and announcements, especially at the National Airport stop, a terminus on the Yellow, Orange and Blue Lines. Confusion is widespread among commuters as well as tourists unfamiliar with the Metro system.

Fairfax County Supervisor Joseph Alexander, a member of Metro's board of directors, recalled watching passengers gaze uncertainly at a poorly marked train. "Nobody can find out whether that's the Yellow, Orange or Blue," he said at yesterday's Metro board meeting.

In addition to the moves now under way to lessen the confusion, officials said they are studying several other measures, including improvements in destination signs on trains, installation of new signs and maps in the National Airport station's entrance and assignment of more Metro employes to the station to answer passengers' questions.

In the past, Metro officials have urged passengers, perplexed about which train to take, to board any train departing from National Airport and then listen for an announcement. If passengers learn they are aboard the wrong train, they can transfer at the Crystal City, Pentagon City or Pentagon stations.

On average, 23,800 passengers a day are riding on Yellow Line trains, according to newly compiled figures issued yesterday by Metro. The Yellow Line, a rail shuttle across the Potomac River, operates between the National Airport and Gallery Place stations. It offers faster trips between parts of Northern Virginia and the District of Columbia than the Blue and Orange Lines.

The new statistics indicate that ridership on the Yellow Line increased by 19 percent during the line's first month, but the total still fell short of earlier forecasts.

About 2,300 passengers are traveling on District-bound Yellow Line trains during the busiest morning hour. Metro officials previously predicted that about 3,500 inbound commuters would now use the Yellow Line during that hour and said they expected this number to climb to about 5,000 after bus service between Virginia and D.C. is reduced June 26.

In another development, Metro officials proposed a new bus route between Friendship Heights and the Van Ness-UDC rail station on Connecticut Avenue NW. A public hearing is tentatively scheduled for July 13.