Two or three times a week, Emily Mann, a retired government clerk, makes the trip downtown from her home on Southern Avenue in Northeast Washington to do volunteer work at a Methodist church.

She gets there by riding the X2 bus.

When Mann goes to Walter Reed Hospital to be treated for glaucoma, visits a friend in Virginia or needs to get to a meeting at the King Library, she travels the same way--by bus.

"I have no other way unless other people take me," she says as the X2 heads down Minnesota Avenue toward town on a recent morning.

For Mann, and for many people in Northeast who don't own cars, the X2 is a lifeline to the outside world. Besides taking them to and from their jobs, it carries children to school, housewives to shopping centers, the elderly on assorted errands and the unemployed in search of work.

The X2 makes an eight-mile trip from the Capitol View Plaza low-income housing project west to Lafayette Square and back again 22 hours a day, seven days a week, carrying almost 12,000 people every day.

And because the X2 is such a workhorse and uses some of the least reliable buses, it's more likely to be early or late, break down somewhere along the route or not show up at all.

According to a Washington Post study, the X2 was the fourth least reliable bus of more than 370 routes surveyed, losing nearly 5 percent of its daily trips. Like eight of the 10 worst routes in the Post survey, it serves an urban and predominantly poor and working-class population in the District of Columbia and the problems it has are typical of those routes.

"The service is very poor," says Mann, who complains the bus is often late and overcrowded.

Not all passengers agree with her assessment.

Preston White, an unemployed housekeeper, points to the stop-and-go nature of the route and its long haul and says he feels Metro is doing the best it can.

White's gripe is not with Metro, but with passenger misconduct and the delays it causes. He says smoking marijuana and cigarettes is commonplace on the X2 and he supports the drivers who have to handle these situations.

"They're just doing their job," says White. "I feel that if you smoke on the bus or do anything wrong on the bus they should put you off."

On this particular morning, there is little conversation among the mostly black, modestly dressed passengers. The loud hissing of the "air-assisted" front and back doors seems to discourage much talking.

From the back of the bus, however, can be heard the funky beat of a popular soul song. A group of teen-agers with school books and canvas bags huddles near the middle of the bus.

"There's really nothing wrong with them playing the radio," says Antonio Abney, a 10th grade student at Phelps Vocational High School.

In fact there is something wrong with it; it's against the law -- and a sign in the front of the bus says so in big letters.

Gesturing to the front of the bus, Abney says, "Some of them drivers , you know, just don't like it, right? And some of them, it's all right with them and they don't say nothing."

The X2 is one of the five routes on what is known as the "Benning Road line" that use so-called "articulated" buses -- oversize vehicles, 15 feet longer than standard buses, which pivot in the middle to handle curves. The buses have a mixed reputation for performance and reliability, but Obie F. Coates, the driver this day, says he prefers the bus because of its power steering.

"I like the handling of it," says Coates. "You aren't tired when you get finished working."

Coates concedes, however, that passengers--particularly those riding or standing in the rear--have a "rough ride."

The worst place to be, according to one passenger, is the turntable, which helps the bus around corners but gives the sensation of an amusement park ride.

Another driver, Calvert Sawyers, who has been assigned to the X2 off-and-on for the last four years, complains of passengers who won't pay and of frequent mechanical failures.

"This is famous for overheating in the summertime," Sawyers says of the articulated bus. "You'll see them stopped everywhere in the street."

Coates says he has yet to experience any mechanical failures on his route but has heard all about them. He's also heard about unruly passengers, but says his biggest problem so far has been with large numbers of "adolescents" who won't move back in the bus.

In general, says Coates, who's been driving buses for Metro for 8 1/2 years and the X2 for several months, he'd rank the route "five on a scale of one-to-10."