State transportation officials last week unveiled plans for a $100-million expansion of Rte. 28 in Fairfax and Loudoun counties that would transform the roadway into a limited-access, multilane expressway.

The project would radically revamp the section of Rte. 28 running from Interstate 66 in Fairfax County to Rte. 7 in Loudoun County, limiting access on and off the 15-mile stretch of road to only 11 interchanges.

Highway officials said the bigger road is needed to accommodate the enormous growth in road use that commercial and residential development along Rte. 28 is expected to produce. No money has yet been allocated for the project and it remains unclear when and from where funds will arrive.

"We don't have any idea when construction might start at this point," said H. M. Shaver Jr., a design engineer with the Virginia Department of Highways and Transportation. Dewberry and Davis, a Fairfax City firm, has been awarded a $2.9 million contract from the state to design plans for the proposed expansion.

Dewberry and Davis's final design proposal for Rte. 28 will not be completed until late 1987 but at this stage, said transportation engineer Reed Winslow, 12 interchanges are planned at the following locations: Interstate 66, Poplar Tree Road, Willard Road, Rte. 50, McLearan Road, Frying Pan Road, Dulles Access Toll Road, Rte. 606, Rte. 846, Rte. 625, Rte. 638, and Rte. 7.

Winslow anticipates two aspects of the project will draw heated responses: environmentalists are likely to raise concerns about the sections of the highway running through Ellanor C. Lawrence and Sully Plantation parks in Fairfax County and developers will probably want more interchanges.

Winslow said that the construction would not have a significant impact on the parks. He also said that although it is possible some of the interchange sites might be eliminated in the final proposal, it is unlikely that more will be added.

The cost of construction, if it follows the full proposals and is started shortly after the design phase is finished, will be between $100 million and $150 million, Winslow said.

Del. Vivian Watts (D-Fairfax) estimates it will be five years at least before construction on the Rte. 28 improvement begins. She said that a combination of limited funds and concerns from homeowners may result in the actual construction being less grandiose than the formal design that Dewberry and Davis eventually proposes.

"I wouldn't be surprised to see modification," said Watts.

Watts said the Rte. 28 project may be the beneficiary of a new willingness in Richmond to fund road construction projects. "There is strong sentiment [statewide] that revenues will have to be raised," said Watts. "People are starting to recognize the need."

Finding money will be only half the task for highway officials and state and local politicians. Accommodating commercial and community interests in both counties will be just as difficult, highway officials concede.

"It's an interesting as well as a sensitive job," said Shaver. "You have to balance these [competing interests] ." A desire to defuse controversy that the Rte. 28 proposals are sure to spark has led officials to open the project to community involvement well in advance of any final decisions. The state will hold community workshops in both Fairfax and Loudoun counties to get feedback early in the planning process, Shaver said.

Highway officials heard early from one resident who was less than enthusiastic about the Rte. 28 proposal. Ken Bombara, who lives in the Cabell's Mill subdivision on Rte. 28 near I-66 said that if both the Rte. 28 plan and a Fairfax County plan to close Walney Road near his subdivision are implemented, his home will be landlocked.

"Obviously something will have to be done about this," said Winslow.

The next Rte. 28 workshop will be on July 30, at Park View High School on Laurel Avenue in Sterling Park.