More and more people are using the Metro subway to make trips that have nothing to do with going home or getting to work -- the classic use to which most of the public traditionally puts a transit system.

A subway ridership survey released yesterday showed that almost one of every four subway riders (24 percent) started his trip from a place other than home or work. The last time Metro asked its riders where they came from or where they were going, 21.5 percent fit the noncommuter category. Metro has been popular from the day it opened with downtown Washington's lunch bunch.

Almost 6 percent of Metro's riders said they would not have made the trip if there had not been a subway, according to the survey. The survey was taken in April and May of this year.

Two out of five of the subway's riders get there in the morning by bus, a fact that has not changed much since the survey a year earlier despite the opening of the Orange Line extension from Rosslyn to Ballston in Arlington County. However, Metro's previously reported ridership increase clearly indicates that the Ballston extension has attracted a substantial number of new transit riders.

Almost 27 percent of the subway's morning riders walk to the station, 14 percent drive and 12 percent are auto passengers.

When all of these factors are combined, the report said, "about 73,600 trips were diverted from automobile to transit. This amounts to about 36,800 vehicles removed from the streets and highways of the Washington area, a gain of 6,800 from last year.

Furthermore, the report said, slightly more than half the people surveyed on the subway said an automobile was available to them to make the trip.

The residences of the subway's Washington area riders are distributed almost equally among the area's three major jurisdictions; 32 percent of them come from the District; 33.9 percent from Maryland and 34.1 percent from Virginia. When all riders are counted, 6 percent of them come from outside the area, proving that Metro is a popular conveyance for tourists.