To avoid the evening tie-up on Rte. 28, Leslie Nelson often lingers in her office for an hour after quitting time -- even if she has nothing to do. Despite such measures, she said, the six-mile commute to her home in Chantilly takes 30 minutes or more.

At British Aerospace Inc., executives instituted a flexible work schedule after employes complained that traffic on Rte. 28 was making it impossible to get to the office on time. But that hardly alleviated the problem.

"When we first moved to Dulles in 1977, commuting back and forth was quite simple," said Paul Harris, speaking on behalf of the firm. "Today it is devastating."

The two were among a parade of speakers who appeared at a public hearing before the Fairfax County Board of Supervisors yesterday to express support for a proposed Rte. 28 tax district. According to the plan, taxes raised from landowners would help pay for up to $392 million in improvements to the road.

The board deferred action on a resolution to create the tax district, saying it wanted to ensure the support of developers who would be affected.

The tax district requires the approval of landowners representing 51 percent of the acreage along Rte. 28, which runs north-south for 15 miles between I-66 in Fairfax County and Rte. 7 in Loudoun County. Some landowners recently expressed concern about the amount of money they may ultimately be forced to pay for the widening project and threatened to withdraw their support. County officials had said they would not agree to a demand by the landowners that the county impose a formal ceiling on the amount of the surtax.

At yesterday's hearing, however, developers and county officials expressed optimism about the prospects for the tax plan. "Everybody wants this to happen," said Curtis M. Coward, an attorney for developers along the corridor.

In meetings with county officials last week and yesterday, developers appeared to soften their demand for a formal ceiling on the surtax. The proposed resolution says simply that the board attaches "great weight" to the original terms of the tax district plan, which allowed for a surtax of up to 20 cents per $100 of assessed value.

Coward said that he anticipates most landowners will agree to the compromise. "My sense is that by the end of the week we'll be there," he said.

Yesterday's public hearing attracted 22 speakers, many of them regular commuters on Rte. 28, who pleaded with the board to do something about the nightmarish traffic conditions they endure morning and evening. "We need your help before an already intolerable situation becomes impossible," said Nelson, the Chantilly homeowner.

But the support was not unanimous. Donald Emerson, speaking on behalf of the Fairfax County Federation of Citizens Associations, expressed concern that the Rte. 28 project would siphon funds from other badly needed road improvements in Northern Virginia.

"Revenues raised by the district will be proportional to land value, which will depend on the amount of development that occurs in the district," he said. "If property values do not increase rapidly enough to service the debt, revenue shortfalls will need to be made up by the state."

Moreover, he said, the amount of development required to pay for the widening project could create a whole new set of traffic problems in the area.

The board deferred action until Monday, when the plan also will be considered by the Loudoun County Board of Supervisors.