New Service For Subways On West Side

A new subway service - the No. 9 train - made its debut yesterday on the West Side of Manhattan. And for awhile, even a subway train was confused.

When that train roared into the 181st IRT station yesterday morning, its lead car called itself the No. 9. The rest of the cars were designated No. 1's. What's a commuter to do? ''I don't know where the stops are,'' said Tammy Williams ''I'm trying to get to 145th but if this is a No. 1, I don't think it'll stop there.'' Faster and Less Crowded

The new service provides ''skip-stop'' service between 6:30 A.M and 7 P.M. on weekdays, freeing the old No. 1 local to skip four stops between 137th and 242d Street. The purpose, says the Transit Authority, is to provide a faster and less crowded ride for people in the Bronx and Upper Manhattan.

Not everyone believes this will happen. Some passengers say they will spend more time on platforms, transferring or waiting for the right train to come along.

By the evening rush hour, pamphlets, maps, announcements and transit officers had helped smooth out the morning's confusion. But some passengers remained grumpy.

''It slows me down because I have to change trains for no good reason,'' complained Frank Gary as he waited yesterday evening at 137th Street for an uptown train to 157th Street. ''I knew about it this morning so I did not get confused.'' Eight Out of Twelve Stops

On the East Side, the IRT No. 7 line resumed express service yesterday for the first time since a track replacement program began in 1985. It dropped, however, one of its old stops at 61st Street in Woodside, Queens, officials said.

Both the No. 1 train and the No. 9 make 8 of 12 stops above 137th Street.

Jared Lebow, a Transit Authority spokesman, said the new line would save up to three minutes on a ride from South Ferry to 242d Street. That's not much, he said, but cumulatively, over the course of a day, enough time is saved to get more use out of the trains. He also said that a total of 28 No. 1 and 9 trains would now run during each rush hour, instead of the 25 that used to run on the No. 1 line.

In response to civic groups that felt that the service discriminated against Harlem residents, transit officials changed the original plan and made both trains stop at 125th Street.