The strip of land on either side of the Dulles Airport Access Highway--has long been considered prime real estate among developers in Fairfax County. And now that the Dulles toll road is under construction, development along the corridor is beginning to boom.

Design plans for 10 office and industrial parks, totaling over seven million square feet of space, are already underway on land facing the access road. And sources in the county say that there are other developments on the drawing boards.

Although plans were made years ago for a commuter road to parallel the restricted access highway, construction of the parallel lanes was held up because the state of Virginia could not afford to build such a road. Some developers, leary of the 10-year delay on nearby I-66, decided to sell their land.

But for those who stuck it out, now is the time to reap the rewards of patience. The Virginia legislature agreed last spring to finance construction of the parallel lanes with bonds to be paid back later in tolls, thereby spawning the Dulles toll road. And that toll road is expected to become the lifeline for all development west of Tysons Corner.

"It's not just land along the toll road that will benefit when they open in 1984 ," said Warren H. Amason, director of International Marketing for the Fairfax County Economic Development Authority. "The toll road will complete a huge rectangle of roads, including the toll road, the beltway south of Tysons Corner to Rte. 50, then extending out Rte. 50 and I-66 to Rte. 28. Land all around this rectangle will benefit and we're beginning to see the activity already."

Juliana Greenleaf, property manager for The Evans Company, said her firm bought land in the Dulles corridor years ago but that it was the decision to fund the toll road that triggered their start-up on the massive Woodland Park project.

"We've had a lot of interest from potential tenants recently," said Greenleaf. "The value of the Dulles corridor and airport is that it allows for first-class office space out in the suburbs."

The Evans Company is planning to build as much as four million square feet of office and industrial space at Woodland Park, a series of 30 buildings ranging between six and eight stories in height. The park will set on 200 acres of land in Herndon, just south of the toll road at the intersection with Centreville Road.

"It's got great visibility," said Greenleaf, adding that she believed the company would break ground for the park within the next two years. They plan to complete the project within 10 to 15 years.

In the short term, the impact of the toll road is heaviest in Reston. With four million square feet of office space already, and less than 10 percent of it vacant, Reston's planners say they expect to double that figure within the next five years.

"The effect of the toll road is that it is focusing the attention of the market on the Dulles corridor," said Charles Carter, manager of Industrial and Commercial Sales for Reston Land Corp., the Mobil Oil subsidiary that is completing the build-out of Reston. "Our plans to build Reston's Town Center used to be far in the future, but with the toll road, we now plan to get started in the next two years."

Carter said Reston Land has chosen to actually restrict land sales now, hoping to hold land until the market for high-density office space moves west from Tysons Corner to Reston. "Reston will eventually be the center for office space, with lower density research and development space developing farther out the Dulles corridor," said Carter.

More than one million square feet of office space will be added to the Reston market this year, but Carter said they will try to stick to a limit of 600,000 square feet a year for the fews years after that, despite what they expect the demand to be..

"Reston will be more attractive than Tysons Corner when the toll road opens," said David Chalmers, vice president for Design and Construction with Lee Sammis Associates, Inc., the developer of Reston's Campus Commons office park.

"Our site will be a five-minute drive from Tysons, and eight minutes from the beltway," said Chalmers. "I defy anyone at Tysons Corner to get out of their office building and onto the beltway during rush-hour in eight minutes.

Chalmers said the coming of the toll road is the reason his firm, backed by a large California developer, is starting construction on three buildings this year.

Lee Sammis already has one building at The Branches and is starting a second. The Branches is a small-scale development that will eventually total 225,000 square feet of space in seven or eight buildings.

The other two new buildings will be the start of Campus Commons, a larger venture of five or six buildings totaling 575,000 square feet of space on a tract just south of the toll road near the intersection with Wiehle Avenue.

As part of the Town Center, The Evans Company plans to build a 24-story office building flanked by two six-story buildings, just north of the toll road at See ROAD, E24, Col. 1 ROAD, From E14 the intersection with Reston Avenue. And Greenleaf said they may be ready to start construction on the 700,000 square foot project within six months.

Other projects underway in Reston include: Tech Park Reston, where Mulligan/Griffin Associates are building an office park that will total 540,000 square feet; Commerce Park 2, where Centennial Development Corp. is building the second of six buildings that will total 500,000 square feet; and Parkridge, where Dupree District Associates, Inc., plans to build 700,000 square feet.

What is happening in Reston is beginning to be felt farther west, particularly in eastern Loudoun County, where there are many acres of industrially-zoned land just north of the airport on Rte. 28.

"Land is not changing hands yet but the developers are coming into the county and looking around," said June Bachtell, director of Loudoun's Department of Economic Development. "They were non-believers up until the point when the funding for the toll road came through."

But there are others who argue that, while it may not look like it, there's plenty of activity along Rte. 28 already. "It's all a matter of positioning," said Amason of the Fairfax Economic Development Authority. "Everyone now knows that the land out there is appropriately zoned and that the toll road is opening it up. For the people with patient money, now is the time to jump."