By car, it's a quick drive to Annapolis. National Airport is a half-hour subway ride, BWI a short train trip. Philadelphia and New York are in commuting distance by Metroliner. Washington is easily accessible. Buses feed the trains and subways. And there is parking for 1,000 cars.

This is New Carrollton, a transportation hub that boosters are wont to call a new "Union Station by the Beltway." What office developers see there is a long-undervalued triangular piece of Prince George's County real estate whose time has finally come: First, its 80-acre Metro East office park is filled to capacity. Now, eight major developers, mostly big league players with national reputations, are vying for what's left, 25.4 prime acres next to the tracks.

Because of its location, one development lawyer said, out-of-town firms with Washington business that "used to go to K Street to hold their meetings would now be just as likely to have them on the Beltway."

Historically, transportation routes have spurred development: Towns sprung up along railroads, at the confluence of rivers, at highway junctions. By this standard, New Carrollton has been been a natural at least since the Metro terminus opened there in 1978.

But the county's downscale image long discouraged top-of-the-line developers. Even now, at least one major developer, Oliver T. Carr Co., looked it over and decided not to bid. In April, Salomon Brothers, the New York investment firm, issued a cautionary report stating that the county's abundance of available cheap land "leaves it open to rampant overbuilding," which could result in substantial unleased office space. Others note that an upscale development will mean equally upscale rents -- up to a third higher than surrounding development because of the deck parking required.

Nonetheless, the competition for the right to build at New Carrollton has been intense. It is about to enter a critical phase as Metro, which owns the tract, narrows the field to five developers. These finalists will be asked to submit detailed proposals, which must include at least a 24-story office building, a 350-room hotel with a minimum of 20 "corporate condominiums," shops and deck parking for about 1,300 more cars.

The proposals are due in December, final selection is scheduled for next year, and work could get under way in 1989. The successful bidder will lease the ground from Metro for 50 years, with an option to renew for 49 years.

And that is just for the first phase. The second phase is to include more office buildings and more parking. Altogether, the development will add 1 million square feet to the triangle's inventory, doubling the current space 2 million square feet and the number of employes, from 5,000 to 10,000. It would be a major employment center with unequaled access.

"It's an opportunity to do a major -- beyond the county -- regional or even a national development," said Dick Kramer, vice chairman of Western Development Corp., a competing firm. "We see it as a high-quality showcase development."

Said Prince George's County Executive Parris Glendening, "Local officials are often accused of hyperbole, but that probably is the most unique transportation hub in the country. All you need is a way to connect it to a port and you've got every mode of transportation there."

The only comparable site in the country, planners said, is Dadeland South, a development eight miles south of Miami. It was built in conjunction with the start of rail service in a suburban area near a highway interchange, and it encompasses a hotel, office buildings and commuter parking.

The New Carrollton tract is framed by the Capital Beltway, Rte. 50 -- soon to be widened and upgraded to interstate status -- and the Metrorail and Amtrak tracks. Ridership at the two rail stations has climbed steadily. Metro carries 12,660 riders each weekday to and from the station. The Amtrak station has become so popular that more than a third of the area's Metroliner passengers now board there, a railroad spokesman said. And vehicular traffic is also substantial: 147,000 a day on the Beltway just north of Rte. 50, and 70,000 daily on Rte. 50 just east of the Beltway.

To minimize traffic congestion and improve roadway access, the county and state are spending $150 million on highway improvements. These are to include a "flyover" ramp to bring westbound Rte. 50 traffic over the Beltway into the triangle and an extension of East-West Highway from Rte. 450, over Rte. 50 and into the triangle by way of Pennsy Drive.

Because of its location, New Carrollton is often described in superlatives. Boosters were calling it the "golden triangle" when doubters saw in it only fool's gold. These days, there are few doubters, and words such as "dramatic," "centerpiece," "showpiece" and "unique" are frequently heard.

Other new office parks on the Beltway are "just more of the same," said John Lally, whose law firm represents PortAmerica, the billion-dollar waterfront project planned for Prince George's Potomac River shoreline, and who is actively involved in the New Carrollton competition. But, like PortAmerica, he said, New Carrollton will attract "another generation of users," bigger and richer than those already there.

This land, which county officials only a decade ago hoped would attract clean warehouses instead of dirty industry, has lured some of the brightest development stars, builders of world-class "signature" projects.

Competing for the New Carrollton tract are Boston-based Leggat, McCall Properties; Boston Properties, owned by U.S. News and World Report Publisher Mortimer Zuckerman; Lerner Enterprises, builders of shopping centers from White Flint to Tysons Corner; the Kaplan Organization of Edison, N.J., and Western Development Corp., builders of Georgetown Park and Washington Harbour.

Also bidding: Rouse and Associates, the firm founded by a nephew of James Rouse that is building a 60-story Philadelphia skyscraper; New Carrollton Limited, builders of Washington Office Park, just beyond the Beltway in Prince George's County, and Key Largo Developments, a Washington-based joint venture by a minority developer, local trade unions and Lally and associates.

"We're not looking to bring in budget or medium-priced hotels," said Daniel Russell III, Key Largo president. "A few international hotels, real class acts, would fit nicely into Prince George's County."

As recently as 1973, the county's master plan for the site called for "storage activities -- wholesale, processing, transportation, construction and industrial uses." A 1977 zoning amendment called for "visually acceptable industrial parks."

The zoning also allowed for offices, and, after Metro's Orange Line opened to its New Carrollton terminus nine years ago, some developers gingerly began testing the waters. Shell Oil, which owned 80 acres in the triangle, spun off substantial parcels to Rouse and Associates, which began to build modestly.

"There was some suggestion that we should concentrate on Montgomery County, which was more affluent," said Claiborn Carr 3d, Rouse regional partner for this area. "But we felt this was a remarkable location, with the roads, train, subway. We saw the potential to get started on the ground floor."

Literally, Rouse broke ground on twin one-story buildings, which housed their first tenants March 1, 1979. Then, Rouse built two three-story buildings, then a two-story building with underground parking, then two one-story buildings, a four-story structure and a five-story building, and finally, a five-story office building -- a total of eight.

Not built by Rouse, the last of 11 office buildings in Metro East is a 16-story tower with a dark glass exterior sometimes called the "Darth Vader" building. After a slow start, Darth Vader, too, is almost all leased.

Digital Equipment Corp., a computer firm, is the park's largest, with 1,200 employes in nine buildings. Its administrative offices are in a Rouse building with day care and fitness centers and a four-story glass atrium with a pianist who plays mornings as employes arrive for work. Outside, a sculpted eagle sits on a pedestal, looking as if it were about to take off -- an apt symbol for the upwardly mobile Metro East office park adjoining the New Carrollton station.

Even the names of the park's two broad boulevards manage to convey the image of striving for success: Corporate Drive, Professional Place. The park has a playground, fitness trail, softball league and 150-room motel.

"You start looking at all that and you say, 'All it needs is the wedding cake,' " said Lee Skillman, a senior Metro planner. "The wedding cake is our centerpiece, a 24-story office building with a restaurant on top, and a hotel abutting the office building with a 200-foot atrium."

By 1983, Metro's vision had been made into a model. In 1985, the agency applied for "mixed use-transportation" zoning, allowing the widest latitude to build. New Carrollton was ready to market, but Metro officials bided their time until June, when they were confident that the marketplace was ready for New Carrollton.

Now, amid all the hype and the hoopla, Rouse's Carr has sounded a singular cautionary note: "If this doesn't lease, it will be a financial failure. You don't need an architecturally exciting project that's empty."