WE HARDLY ever travel, only for a very special reason," says Georg Fritsch, the Vienna State Opera's director of administration, talking about the enormous cost and complication of bringing the company to the United States for the first time.

Small wonder: Besides $1 million worth of scenery, props and costumes moved by ship and 3 1/2 tons of musical instruments (some of them very old and valuable) coming by plane, the operation involves transporting 406 people to Washington. They are coming by 34 different routes, arriving and departing on a complex schedule according to what they have to do and when.

"In this case," Fritsch said, "the special reason was the invitation from the Kennedy Center and Martin Feinstein. In New York they asked us, 'Why is the Vienna State Opera going to Washington and not to New York?' The answer is simple: Because we were invited to go to Washington."

As a result, 23 trailer trucks, each 40 feet long, rolled into the Kennedy Center last week and backed into the massive stage doors of the Opera House, where the Vienna company will open on Friday night. The cargo -- insured for $1 million -- had been traveling since Sept. 10, first in a freight train one-fifth of a mile long running from Vienna to Hamburg, then on a ship from Hamburg to Baltimore.

Stagehands opened the doors on a truck and began unpacking the stuff of dreams: the dungeon where Florestan languishes in "Fidelio," waiting for death or deliverance; the Isle of Naxos where Ariadne loses one lover and finds another; and the seven veils of Salome.

Backstage at the Opera House, more than 40 Viennese stagehands and technicians stood in a corner, most of them neatly dressed in business suits and carrying overnight bags. The regular Kennedy Center stagehands eyed them skeptically. "There's one cool cat in that crowd," said one to another. "He came on in blue jeans."

"By the end of the run," commented a Kennedy Center staffer, "the two crews will be close friends, and they'll exchange presents when the Viennese go home. It's happened already with the crews from La Scala, the Paris Opera, the Bolshoi."

It all began in 1974 in Berlin.

Martin Feinstein, then the artistic director of the Kennedy Center, was in the office of Egon Seefehlner when word arrived that Seefehlner was released from his contract with the Berlin Opera and could become the general director in Vienna. Feinstein immediately invited the Vienna Opera to the Kennedy Center, but did not clinch the deal until 1977. By then, he had persuaded the opera company that is should perform in Washington, but there was still a small question of finances. Cost of the trip, not including the salaries of the orchestra and chorus, is currently estimated at $3.2 million, and the company's normal budget couldn't handle it.

In 1977, after a tense three-day wait, he was given an evening appointment with the Austrian minister of finance. He arrived a little early, he recalls, and "there was a party going on. I found the finance minister, reminded him of our appointment, and he told me he would see me in a few minutes. At the appointed time, he brought me into his office and we began to negotiate, while the party continued outside."

The original plan -- once Feinstein had used his considerable powers of persuasion, and agreement had been reached on singers, conductors and repertoire -- was to have the visit last year. The trip had to be postponed when Austria had a spell of financial austerity. For a while, the Kennedy Center was planning to host LaScala in September and Vienna in October of this year -- then La Scala canceled, also because of financial problems. In fact, the Vienna visit may be the last of the great international operatic extravangazas that have highlighted recent seasons at the Kennedy Center -- partly because money is getting righter, but even more becaue Martin Feinstein is no longer in charge of arranging such visits.

Costs of the trip are being split between the Austrian government and the Kennedy Center, which has raised money from the Morris and Gwendolyn Cafritz Foundation, IBM, other private gifts and box-office sales with ticket prices that range up to $100 for a good seat at a gala evening. The orchestra and chorus, which receive a year-roung salary from the Austrian government, are thrown in free.

To keep track of the 406 participants in the visit, the opera company has printed a small booklet in which a number is assigned to everyone involved. Conductor Karl Boehm is given No. 1; Leonard Bernstein and Zubin Mehta have 2 and 3 respectively; solo singers come next, the women having lower numbers than the men, and you can tell which singers were added at the last minute, because they have numbers over 400.

Besides describing who will be arriving when (Bernstein last Friday, Boehm yesterday, most of the orchestra today and the chorus tomorrow), the booklet has useful phone numbers (the Austrian Embassy, the Kennedy Center, hotels) and standard tourist information.

The visitors are advised on how much to tip a waiter or taxi driver, notified that the time will shift from daylight saving to standard during their visit and warned not to plug European electrical equipment into American outlets without an adapter. One section, titled (in German) "For Your Safety" begins, "We do not wish to alarm you unnecessarily," but warns that "even in Washington, DC." there are parts of town where a visitor should be careful (including "14th Street noerdich der Massachusetts Avenue und Capitol Hill"). Such areas as Georgetown, Wisconsin Avenue and the neighborhoods around the Watergate and the Hilton are safer, visitors are told.

It is not always easy to find "Toiletten, " the booklet warns, and it advises that "Sie heissen meist 'Rest Rooms', aber auch 'Lounge' oder 'Comfort Station.'"

Except for a few advance men (including Fritsch and travel agent Roland Latzko, who has been here three times since July 1978), the stagehands were the first to arrive, along with one of the company's 20 costume and makeup artists. The visitors are distributed among five local hotels -- VIPs (including conductors, soloists and management) at the Watergate, stagehands at the Howard Johnson across the street from Watergate, most of the orchestra at the Capital Hilton and the chorus at Stouffers in Crystal City. Some of the nonsuperstar soloists, the prompter and members of the music staff are at the Intrigue, a few blocks from Kennedy Center. About 40 percent of the company will have single rooms; those with less clout will double up. The total hotel bill is estimated between $250,000 and $300,000 -- not bad for 400 people for two weeks. Members of the company will be given a daily allowance for meals.

"We wanted to put everyone in the Sheraton-Park so we could have the whole company together." said Latzko, "but they were in the middle of reconstruction, and we did not know whether they would be ready." As it worked out, the two most numerous groups -- 114 orchestral musicians and 110 members of the chorus -- are at the hotels most distant from the Opera House, so that there will be buses (supplied by the Kennedy Center ) shuttling back and forth for rehearsals and performances. The number of buses will vary according to the music and the number of people required -- two for "Ariadne aug Naxos," four or perhaps five for ""Fidelio."

Among the instruments coming over with the orchestra are the company's own harmonium and celeste. "We had to bring our own." Fritsch explained, " because our standard pitch is higher than yours and these instruments have fixed pitches, so we would be out of tune. We are using an American piano and harpsichord, whose tuning can be adjusted, and we are bringing back to the United States two harps that we ordered five years ago from Chicago. They are the best harps in the world, in our opinion."

Along with the local harpsichord and piano, the company will be hiring some local performers to serve as extras.

In Washington, some members of the company will be working harder than they do at home. In its normal season, the company has about 100 rehearsals and 300 public performances -- plus festival appearances at Salzburg and Bregenz. This is the longest season of any opera company in the world and allows only 2 1/2 to 3 weeks of vacation each year for regular members of the orchestra. But normally, an orchestra member is expected to give only 11 to 18 performances per month, the exact number depending on his instrument and seniority. Stagehands normally work a five-day week, but will be working at least six in Washington. "They will be given one free day per week if possible," said Fritsch, "and of course they will receive extra pay for extra work."

No special tours or other group activities are planned for members of the company during their free time because their working hours will be so varied, but Latzko (who normally runs a travel agency in Vienna) will be on call to help people find what they are looking for and to advise them on restaurants, tours, museums and other pastimes.

"We are very proud of our opera company," says Fritsch, "and we enjoy the opportunity to show what we can do. Enthusiasm is very high among those who are coming to the Kennedy Center because the people here are expert professionals -- very ingenious -- and the stage suits our needs.

"Its dimensions and facilities are very much like our own. We can stage our own productions with only small changes in the scenery that will not be noticeable from the audience. We are really lifting up an entire production and moving it to another continent.

"The production being shown here is the original, just as it is done in Vienna, and we are hoping that the American people will develop such a taste for it, either by attending or through the broadcast performances, that they will want to come and hear it in Vienna next year."