The train, familiar to commuters working in big cities like New York and Philadelphia, is capturing a steadily increasing number of the 260,000 persons who travel into Washington every weekday to work.

Running on two lines between Baltimore and Washington and one line that connects upper Montgomery and Frederick counties to union Station, the commuter trains are standing-room-only evey weekdaydespite being totally unpublicized, uncomfortable, and ancient.

"We can't go out and market this service because we don't have any place else to put people," said Charles H. Smith of the Maryland Department of Transportation, which subsidizes the trains.

"There is tremendous potential here, if we'll just use it," said Montgomery County Counciman john Menke, who rides the train himself between Rockville and Branesville where he lives.

Menke points to statistics that show that on his line daily ridership has jumped in two years from 1,308 persons to 2,088. When the two lines from Baltimore are added in, a total of about 3,000 persons now use commuter tains to get into Washington daily.

While commuters avoid the downtown traffic, the parking lots that surround the suburban and rural train stations are spawning impressive rush hour traffic jams of their own as commuters park in the morning and rush to leave at night.

Despite their growing popularity, however, the trains are all running deficits in the hundreds of thousands of dollars. The Chessie System, which operates two of the commuter lines, claims it is losing $1 million a year on the service and is pressing Maryland to pick up the difference. Negotiations are stalled.

"One of the things we have to ask ourselves in who are we really subsidizing," Smith said.He said, and a reporter's check confirmed, that more than half of the cars parked in the lots at Brunswick and Point of Rocks - two Maryland railroad towns on the Potomac River - come from Virginia.

"By subsidzing, we're really encouraging people to move out there," Smith said. Indeed, a Loudoun County real estate firm is running radio ads in Washington pointing out the proximity of its properties to the "Maryland commuter train."

Most of the riders board at closer-in locations such as Gaithersburg on the Chessie line or Odenton on the ConRail train from Baltimore. One of the reasons they are taking the train is Washington's new subway system.

In the year since the five-mile subway line opened downtown, wit Union Station as one of its stops, 17 per cent of the commuter train riders continued their trips on the subway. It is an easy walk from the train platform to the Metro escalator.

Transportation planners are certain commuter train demand will increase even more when Metro opens 12 more miles and 17 more stations on July 1 and makes such employment centers as the New Southwest and the Pentagon readily accessible by transit.

Another reason is that there has been a population boom in upper Montgomery County, Frederick County, and Loudoun County as people ahve been forced or have chosen to buy farther out where homes are cheaper but distances longer.

A final reason is that some people simply don't like to drive, "Even if this train breaks down, it's better than driving," said Pat Nixon (no relation to the former President), who lives in Glen Burnie but rides the train from Odenton.

Then she transfers to the subway, rides it to Connecticut Avenue and L Street NW, and walks three blocks to the Federa National Mortgage Association where she works.

Most regular commuters buy weekly or monthly passes that give them unlimited ridership. The monthly pass between Odenton and Washington, for example, costs $44 monthly, and the Washington-Gaithersburg pass costs $42.70.

"We could charge more, but that would be an insult ot our passengers, considering the condition of the trains," said Smith.

Pat Nixon's ConRail train is literally vintage 1915 electric, and it runs on the old Penn Central right-ofway between Washington and Baltimore (see map). The windows are open; old-style ceiling fans stir around the hot air in the three jammed cars.

"If you don't get her by 5:10, you stand," one passanger advised.

The train leaves Union Station for Baltimore at 5:25 and 6:10p.m. daily. Despite its full load, it runs a deficlt of $738,000 a year, officials say. At the moment, the federal government is picking up most of that, but the total cost will revert to Maryland shortly. The long-term future of that train is undecided, according the Smith.

It enters Washington along the same corridor as the Metro line to New Carrolton, which is under construction and scheduled to open in June 1979. "We're subdidizing both the Metro and the commuter train - it may be better to run a bus from Odenton to New Carrolton and put people on the Metro there," he said.

The other Maryland commuter trains-operated by the Chessie System - are more modern. The oldest cars date back to 1920 and the newest to the early 1950s. Some of them even have operating air conditioning units. But there is no more room.

The most popular train is the 5 p.m. from Union Station to Brunswick, Md., with stops in Silver Spring, Forest Glen, Kensington, Garett Park, Rockville, Washington Grove, Gaithersburg, Germantown, Boyd, Buck Lodge, Barnesville, Dickerson and Point of Rocks.

Some fo the long-time riders have noticed the crowds. "It's getting tough," said Robert Praskievicz, who works at the Government Printing Office near Union Station and lives in Gaithersburg. "There used to always be a seat. Now it's standing room to Rockville."

The car Prakievicz was sitting in filled up first. "THis is the one with the good air conditioning," he said. A few minutes before Gaithersburg, Pavaskievicz got up and started for the door.

"Watch," he said. "Before the train stops people are going to be jumping off of it and running full tilt for the parking lot. If you don't get out of that lot in the first wave, it takes 15 or 20 minutes."

His prediction was totally accurate.

Maryland is planning more cars and improved service on the Brunswick line, and has been ironing our labor agreements to get second-hand equipment refurbished.

Labor costs are the primary factor - they amount to 73 per cent - in the operating deficit. It is a problem experienced by every public transit system in the country. But another big factor in the commuter train cost is the fee that is required for each car that enters and leaves the Washington terminal - the big rail yard that serves Union Station.

That fee is about$40 a car - or $80 for a round trip.

To cut that cost, Maryland planners are studying the possible transfer of commuter train passengers to the Metro subway at the Silver Spring station when Metro opens there, scheduled for November. The two stations are not convenient to each other, and a jury-rigged solution is under study. Under that proposal, the commuter train would never enter Washington Terminal and pay the fee, but the passengers would still have access to downtown.

If commuter train service is going to continue, however, it wil require continued public subsidies. Maryland is putting about $600,000 a year into the Chessie operation, and Chessie claims its loss is $1 million.

Maryland transportation officials, who say they have studied the books again and again, conceded "theyr are losing money," as one said, but argue over the figure.

"From a railroad standpoint, we'd love to get out of it," said Chessie's Jack Griffin, who runs the passenger service. "It's just not a good business venture."