Dave Hardy doesn't ride the 152 anymore. The 52-year-old oceanographer clocks out late these days, hours after the 5:35 p.m. train to Baltimore slips out of its berth at Union Station. A new work schedule at the Department of Commerce ended his two years of rail commuting earlier this year.

But the Catonsville resident joined his former fellow commuters last week for one more ride down memory lane on the B&O Railroad's train number 152.

Hardy called in sick, abandoned the car he now drives every morning at Penn Station in Baltimore and caught Amtrak to Washington.

All in time for the B&O's annual Christmas ride home.

"This was one nut who had to come back for the party," Hardy said, sweeping his hand through the gold and red tinsel-strewn diesel engine car. "I love all these people."

"All these people" included a 33-year-old research analyst with the Pentagon, a 23-year-old account supervisor with an insurance company who said she wished she were still 18, a 26-year-old editor whose husband rode the 5:05 and didn't want to come to the party, a cost analyst of undisclosed age who had the deepest Christmas baritone on board, and a Montgomery County politician droning on about the state transportation system from one of the front seats.

These were just a few of the approximately 50 riders who looked like they were having quite a jolly time at the 10th annual Christmas party, hosted and paid for by the local chapter of the Alliance of Rail Citizens for Progress, a nationwide organization that boosts train travel. A similar party was held two nights earlier from Union Station to Brunswick.

The passengers dipped into cardboard boxes of potato chips and french onion dip when the large pretzels ran out. They harmonized renditions of "Jingle Bells" as the three-car train stopped at places like Riverdale, Berwyn and St. Dennis. And they sipped at brown paper bags. Some sipped a lot.

"Everyone on to Baltimore. I'll drive you all home," shouted one wobbly reveler in business garb perched between blue cloth chairs and a laminated table and three similarly suited friends. There were quite a few brown bags on their table.

A few groans heavy with cheese snacks and Miller Lites went up with the onward suggestion. Regina Burns, who thought about four times before finally deciding not to go to Baltimore, had to get off at Laurel. She was the one who said she'd like to be a teen-ager again. Burns sat across from Melanie Dzwonchyk, whom she met on the train. They live a few doors away from each other and now, they say, are friends. Dzwonchyk, an editor at the National Trust for Historic Preservation with shocks and shocks of burnished red hair, also hopped off at Laurel to meet her husband. He was the one who took the 5:05.

"I love your train, Mr. Griffin," shouted Burns before disembarking in her stark white Nike running shoes with light blue tabs at the heels. Jack Griffin was pointed out by a passerby as the man who keeps the trains running. Griffin, B&O's manager of passenger service, squeezed into the packed train to come along for the party ride.

"Everyone looks after you here," Burns explained. "If you fall asleep, the conductor will wake you up before your stop. If you forget your jacket, someone will say, 'Hey you forgot your jacket.' It's great."

Hardy agreed. The 5:35 rail diesel car built in the early '50s, with scratched tile floors and cramped quarters, may not be Amtrak-elegant, but for Hardy it's the only train on the tracks.

"I really, really, really miss riding it. For a number of years this was my whole social life," said Hardy, a bachelor, from under a line of miniature red reindeers hanging from the ceiling.

"In the train you just sort of met people: guys, girls, whatever. Now my social life is going down the drain. Suddenly," Hardy continued with half a laugh, "I'm old, ugly and rundown."

Well, not that rundown. At the 6:01 Laurel stop, Hardy, dressed in flannels and navy, leaped off quickly and reappeared with a librarian on his arm. Dinner in Baltimore?

Sporting a sly smile, Hardy fended off the obvious and said, "Ah, who'd want an old guy like me?"