There were colonels from the Pentagon eating lunch at the Hawk and Dove Restaurant on Capitol Hill. Workers from the District Building were inspecting the Pentagon shopping mall. A researcher from the Library of Congress met his wife for lunch near her office at Dupont Circle.

Yesterday may have been Washington's longest lunch hour as the Metro transit opened its new Blue Line and thousands of persons thronged its trains at noontime to sample the subway and visit parts of the area they had seldom been to before.

At times, the crush on the lunch-hour trains was so great that doors had trouble closing. It took so long for passengers to get on and off that the delay between trains built up to about half an hour from 1 to 1:30 p.m. instead of the scheduled 10 minutes.

Some of the riders complained that they felt like sardines, and would get back to their offices later than they were supposed to. but generally the people on the packed trains seemed to be cheerful.

"There's just bound to be some kind of problem for the first few days," said Roscoe Egger, as he took the train back from Capitol Hill to his office at 18th and K Streets NW. "You know, this is a wonderful thing for the city."

"I think this is going to open then city up a great deal," said Edward Brooks, a computer specialist for the Navy Department who rode the subway from his office in Rosslyn to have lunch at Mr. Henry's on Capitol Hill. "People will be able to communicate with people in different areas." he continued, and break out of their own little circles. It's beautiful."

Brooks sai d he normally eats lunch around the corner from his office in Rosslyn.

For workers at the Pentagon, isolated by a sea of parking lots and a maze of highways, the lunch time the subway ride provided a chance to see and be see by the rest of the area.

Until yesterday, nearly all the Pentagon workers ate lunch in the huge building itself. Yesterday, many of them boarded the subway and headed for the District.

Harry Williams, of the Institute for Defense Analysis at the Pentagon said he was going to Connecticut Avenue and K Street NW., just eight minutes away on the subway.

"It takes about 20-25 minutes to get there by cab," Williams said, +and costs about $5. With your own car it's impossible to get there because of the traffic and you can't park. Now it is going to take 80 cents instead of $10. Of course, if we were paying the full cost it might be $5."

Normally, many employees at the Penatgon get only 30 minutes for lunch and two 15-minute coffee breaks during the day.Diana Rich, a secretary for the Department of the Army, said she consolidated all her time off for an hour-long lunch period, and was going to downtown Washington for lunch and some shopping. She said many other secretaries were doing the same thing.

Meanwhile, back at the Pentagon itself store managers on the shopping mall in the building's lower level said business was up yesterday with many new faces, apparently people who work elsewhere.

The Pentagon businessmen said they afraid that the subway soon might hurt them.

James B. Trent, manager of Woodward and Lothrop's branch at the Pentagon, said, "How long that 5 per cent (increase) will hold is a completely different question. There's been a captive audience (for businesses here) with nowhere else to go. The subway gives these people a chance to get out."

Even before the Blue Line opened yesterday, Metro's Red Line, which, started running a year ago between lower Connecticut Avenue NE, had an important impact on lunchtime in Washington.

The most conspicuous group of travelers seemed to be the lawyers who rode the subway from court buildings that had been isolated downtown to the restaurants near Connecticut Avenue.

The manager at one of their destinations, Duke Ziebert's restaurant at 1722 L Street NW, said business hadn't been affected by the new subway line, but he added that yesterday probably wasn't a good day for judging things because of the start of the long holiday weekend when lunch time business normally declines.

Camille Richaudeau, the owner of Chez Camille, 1737 De Sales Street NW, said his business was up slightly, but he wouldn't say whether aby notables had comes from formerly out-of-the-way places such as Capitol Hill.

"I'm very discreet," Richaudeau explained, "but I'm very enthusiastic about Metro. Oo, la la la la la. Metro is the best thing for this city. For years we suffered (while the subway was being built and streets were torn up). Now we have our reward."

Not all the long-distance lunch-goers were going to prestigious at the Internal Revenue Service, who boarded the subway at the Federal Triangle station, said she was heading for lunch with some friends at Crystal City in Arlington.

Besides the lunchgoers, the noon-time crowd on Metro included serious errand-runners, among them a historian at the State Department going to a photo shop on Capitol Hill and a colonel from the Pentagon buying a book at the National Visitors Center in Union Station.

However, some people interviewed on the trains said they were just making trial runs to see if they could reach different destinations on future lunch hours.

Many others seemed mainly interested in seeing Metro itself, not with where they were going.

"I've been climbing over it for six years," said one IRS employee. "Now I just want to ride it."