Outside the Bureau of Engraving and Printing, the city's busiest bus stop for Virginia commuters, they're looking forward to the Metro subway with the kind of enthusiasm usually reserved for walking the plank.

"I think it's going to be a mess," said Victor Muller, a computer analyst for the Agriculture Department, on a recent afternoon as crowds of office workers scanned the horizon for the bus that would bear them home.

"It's going to take more time, cost more money, and be a lot more confusing," Muller said. "I just don't think it's a good idea."

In fact, Metro officials contend, the fare system for a combination bus and subway ride sounds more complicated on paper than it will be in practice. The actual fare should be within a dime of what Virginia commuters are now paying.

While Metro's long awaited Blue Line officially opens today, the real hour of reckoning for many Northern Virginians won't come until September. It is then that many Virginia bus routes that now deposit the city-bound at various points throughout Washington will terminate at the Pentagon Metro station. In September, it will be the subway or hiking boots.

Actually, for the hordes baking in the late afternoon sun, the best thing about the opening of the Blue Line seemed to be the opportunity it presented to voice complaints about the bus system.

"Hey," said Muller to several of his coworkers and fellow commuters, "this is your big chance to complain about Metro. You don't want to miss that, do you?"

Muller and his friends weren't the only ones for whom Metro's track record with the buses didn't generate much hope for the subway.

"If they're too stupid to run a bus system, how could anybody in their right mind trust them to run a subway?" asked Jennings R. Hartsell, an Arlington resident who rides the bus "as a last resort."

There followed a long list of complaints running from faulty air conditioning to buses that never came. The list included a warning to "remember that the same people who can't fix the air conditioning will be the people working on the subway brakes."

While most commuters riding buses that will come to the end of the line at the Pentagon in September are planning to take a test ride before D-Day, others are taking a more cautious approach. Fred DeRoo, an Annandale resident who works at the Agriculture Department, said "I just don't trust Metro not to mess it up." Instead, after the September switchover, he plans to join a four-person carpool until "I hear by word-of-mouth how it's working."

Although several commuters hinted darkly that it seemed unconstitutional for Metro to take away their freedom to choose between the bus or the subway after the Pentagon stop, the real push for the new system came from Northern Virginia political leaders.

Running both buses and subways to the same destinations, contends Arlington County Board Chairman Joseph S. Wholey, one of the principal backers of the termination system, would mean that commuters simply wouldn't give the new subway system a chance.

"It's just not reasonable for tax-payers to pay for buses and trains that are both running half empty." Wholey said. By leaving commuters without the option of continuing into the city on the bus, Wholey hopes that the subway will be paying 100 per cent of its operating costs out of the farebox, not the taxpayers' pockets, by the early 1980's.

Such long-range planning mattered little to the sidewalk grumblers on 14th Street, however, and a question arose. Where, it was asked, was their sense of adventure the pioneer spirit that has got this country through thick and thin? "Are you crazy?" said one woman in a yellow pantsuit. "That's not going to be adventure, that's going to be chaos. Who needs chaos at seven in the morning?"

There were a few brave souls, however, who planned to take the plunge at the Pentagon this morning. "I expect like a number of people I'll learn about it," said M. B. Morgan, an Army colonel who works at the Forrestal building. "It may be twice as complicated, but I'll go through the mad shuffle with the rest of them."