Two years after the coming of Metro, Arlington's Rosslyn-to-Ballston corridor is reaping the fruits of development that officials and builders had predicted.

Last year three new office buildings sprouted along the three-mile rapid rail line and developers this year plan to begin five more office projects near the Rosslyn, Court House and Ballston terminals. Those eight buildings along this burgeoning commercial corridor will contain 2.5 million square feet of office space--half again the space currently there.

A number of developments are planned. County officials are expected to approve developer Oliver T. Carr's plans for a 745,000-square-foot office building complex and 344 apartment units on a 10-acre site at the southwest intersection of Glebe Road and Washington Boulevard near the Ballston Metro station at the end of the Orange Line. Also, county planners this week began taking developers' proposals for a 280,000-square-foot commercial-residential complex on county-owned land near the Court House Metro station.

Economic development officials and urban planners have mixed views on the future of the Ballston corridor. County planners are bullish, saying lower rental costs and the convenience of the Metro will spur what they believe is a tendency for associations and corporate offices to move to the suburbs. County plans call for "nodules" of residential and commercial development at each of the five Orange Line terminals, with building height and density tapering down as development moves away from the metro sites. Detailed development plans have been completed for Ballston, Court House and Rosslyn and are being developed for Virginia Square and Clarendon.

But the Ballston corridor will never attract large-scale development like that near Crystal City and Pentagon City, some urban planners say. They contend that the strip's fragmented development is not attractive enough to appeal to image-conscious firms, and that the corridor lacks the proximity to the Pentagon and National Airport that has led to the construction of 7 million square feet of office space at Crystal City, with an additional three million proposed or under construction.

Here are some of the projects under way in the Ballston-to-Rosslyn corridor:

A 12-story, 360,000-square-foot office building at 1310 N. Court House Road near the Court House Metro station. New York developer Alfred Ginsburg has scheduled occupancy to begin in Fall of 1982.

Park Place, a 168,000-foot office building between the River Place cooperative and the Xerox building in Rosslyn. The Kaempfer Company Inc., in cooperation with Walker and Dunlop Inc., expects to finish the building late this year.

The National Milk Producers Federation building at 1840 Wilson Blvd. near the Court House Metro. Federation officials hope to lease half of the 45,000 feet of office space before the building's opening late this summer.

In addition, construction is expected to begin this year on:

The 450,000-square-foot "twin" of Twin Towers at 1000 Wilson Blvd. in Rosslyn, the counterpart to the silver office building--whose 29-story height the Interior Department tried to block--that currently houses offices of Gannett Publishing Co.'s planned newspaper, USA Today, and several large defense contractors. The developers, Twin Towers Associates, say they hope to break ground for the $50 million building within three months.

Colonial Village, a 760,000-square-foot office building on Wilson Boulevard directly opposite the Court House station. The building is being developed by Colonial Village Inc.

Ground breaking dates have not been set for developer Paul Berman's 251,000-square-foot building at 4500 Fairfax Dr. next to Carr's Pocahantas project in Ballston nor for Quadrangle Development Corp.'s 340,000-square-foot office building at 550 N. Glebe Rd., also in Ballston. Developer Herbert Morgan says he hopes to begin construction this fall on a 175,000-square-foot office building east of the Court House metro.

Site approval has been deferred for the controversial Olmsted Foundation building at the southwest corner of North Highland and North Fairfax Drive near the Clarendon station; the 255,000-square-foot building has encountered opposition from Washington planners because it allegedly vies with the Washington Monument for dominance of the Washington skyline.

Arlington planners also envision:

Office and residential developments at the Virginia Square and Clarendon stations, where recently more than 40 tracts of 30,000 square feet or more have been assembled. County officials are completing detailed "sector plans" for those two areas.

A complete renovation of the Parkington shopping center at the southeast corner of Glebe Road and Wilson Boulevard in Ballston. The complex now houses a Hecht Co. department store and several smaller retail stores.

Development by Costain Washington, Inc. of a 3 1/2-acre tract at the northeast corner of the intersection of Wilson Boulevard and Glebe Road near Ballston.

Employes of the Arlington County economic development office cite a number of factors they feel will bring continued growth to the corridor.

"The furthest existing station in Arlington is twice as close to downtown Washington (the Farragut West metro station) than the nearest station in suburban Maryland," said development staffer David Dantzler, who pointed out that Arlington County has a Metro stop for every 16,000 of its residents, the "lowest ratio of any jurisdiction in the metropolitan area."

A subway ride from Ballston to Farragut West is about 12 minutes, compared with 22 minutes from Cheverly in Prince George's County and 25 minutes from Silver Spring in Montgomery County, according to Metro statistics.

County economic development staffers expect to lure organizations with lower office rental rates. Staff member Joclyn Holland said Arlington rents are a third less than those in the District; currently new office space in Arlington is advertised for prices ranging from $18 to $24 a square foot.

Arlington economic development chief Tom Parker said the opening this fall of I-66 north of the Metro corridor may stimulate hotel construction between Ballston and Rosslyn.

Urban planner Stephen Fuller of George Washington University is less optimistic about the Ballston corridor's ability to attract national corporations or other large organizations as compared with the Crystal City area, which, in addition to its current transportation links, will gain a direct subway link across the Potomac in late 1982.

"The problem with the Ballston corridor is that it's stretched out for several miles.... I think that by stretching it out (planners) are disrupting their advantage," said Fuller, who works part time for the Alexandria branch of EDAW Inc., a national urban planning firm. He believes a tightly clustered and highly visible development acts as a magnet for organizations which want to have their headquarters in a vital-looking area.

"There's no sense of visual quality or organizational unity in that (Ballston) area," he continued. "It doesn't look very healthy, economically healthy, that is."

Thomas Carr, project manager for the $100 million Pocahantas project near Ballston, maintains that the complex will become the focal point Fuller says the corridor lacks: "There has to be some sort of critical mass there to attract people.... It's got to look pretty good," he said of his project, which calls for three high-rise office buildings and two apartment buildings.

Parker says the county is committed to the cluster concept of development, calling it "a very human and exciting redevelopment as opposed to the wholesale redevelopment of Rosslyn."

County Board Chairman Stephen H. Detwiler agrees. "This is the opposite of strip development," he said. Detwiler forsees each of the development clusters taking on its own character in response to market demands. Rosslyn, he said, is obviously a commercial office development, Ballston a commercial-residential area, and Court House a mixed-used development coordinated with county government facilities.

He predicted that Virginia Square, where George Mason University owns large amounts of land, will become an educational-cultural center and said that Clarendon, which 30 years ago was Northern Virginia's main shopping center and which now hosts a number of Asian restaurants and stores, may become Arlington's "Chinatown."