Though Clarence Charlton is homeless, he knows he has a warm and dry place to sleep - as long as he doesn't mind waking up several miles away from where he laid his head down.

Charlton, like hundreds of New York's street people, calls the city's subway system home, and officials say they expect the numbers to surge as winter sets in."I can always get on the subway. I usually have the fare," said Charlton, 78, a former mental patient who was wearing a black-knit cap, grimy pants, no shirt, a sweater and tweed coat one day last week. Bedroom slippers failed to cover his swollen feet.

"In the daytime I'm out on the bench, and at nighttime I get in the subway," he said, lighting a cigarette butt, which he says helps his asthma. "In bad weather, I'll go underground."

Charlton had company that day at the 179th Street Station in Queens. Another homeless man was at the other end of the platform, and at least eight already were on the E train when it rolled up to start its run to Manhattan.

As the winds get colder, New York's subways are drawing ever more homeless people. The attraction: a warm, relatively safe environment, all for a dollar. Trains like the E line, whose route never goes above ground, are particularly popular because they stay warmer.

For many riders, the disheveled and often unbathed passengers are not welcome on the nation's largest transit system.

"They stink. They're dirty. They can smell up a whole train," said passenger Bernard Nashofer.

Transit police walk a thin line, rousting homeless people who cause trouble but letting the others sleep. Maintenance crews find themselves cleaning the kinds of messes that subways weren't meant for. Subway passengers learn to select cars by scent.

In response, the Metropolitan Transit Authority approved a plan last week to hire the Volunteers of America, a social service group, to patrol subway platforms and trains. Members plan to talk to the homeless and offer them the group's shelter as an alternative to sleeping underground. But many homeless people shun shelters, saying they don't feel safe in them.

Last summer the transit authority estimated there were 1,400 people using its trains and stations as home. Advocates for the homeless say that's far too low an estimate, and the authority admits the number will be much greater this winter.

The problem is not unique to New York, but mainly is an issue only in cities where buses and subways run all night. In Los Angeles, transit officials say, many homeless people, drifters and alcoholics ride buses from one end of the line to the other all night long.

"Because the homeless situation has increased in the community, I would expect public transit would get its share," said Leilia Bailey, transit director of the Southern California Rapid Transit District.

There is no policy against riding the buses over and over as long as people pay the fares, she said. New York's transit system also has no such ban.

On a Manhattan-bound E train at midnight one day last week at least 18 homeless men and one woman were sleeping. Among them was a gray-haired man with a cane and a man face down over four seats, his right foot in a cast and his crutches under the seats.

An Asian man with few teeth in his mouth and few English words in his vocabulary wrapped paper napkins around a bleeding hand. "I hit," he explained. Another man had his head wrapped in a black scarf, topped by a fake-fur cap and a hard hat. Three large suitcases surrounded him.

"It's like a hotel on wheels," said Robert Torres, a 27-year-old platform conductor.

"Eight years ago, you'd see one or two in the whole train. Now you'll see six or seven in one car," he said.

Constantine Sidamon-Eristoff, a lawyer who is on the transit authority board of directors, said the transit police must exercise more authority over the homeless.

"If they've paid their dollar they have a right, providing they comport themselves with dignity," he said. "But if they take up several seats, urinate, defecate, then they should be removed."

But Transit Police Chief Vincent Del Castillo, noting that "homelessness is not a crime," said criminals and fare-beaters take precedence among his force of 3,800.

One homeless man said he had little choice but to use the transit system as his home.

"There's no other place you can stay in the winter," said Ray Smith, 31. "It's safer in the street than it is in the shelter. This is one of the few places where you can live in harmony. And it's clean."