When Fairfax County Supervisor Nancy K. Falck drives down Haycock Road, in her mind's eye she sees a four-lane street that is a major access route to the West Falls Church Metro station.

When state Sen. Clive L. DuVal 2d of Arlington travels the same road, he envisions something entirely different: a hilly, predominantly residential two-lane street.

Though their visions are not mutually exclusive, there's one thing that Republican Falck and Democrat DuVal see that is exactly the same -- votes.

The section of Haycock Road under dispute is a 3,600-foot sliver of pavement between Rte. 7 and Great Falls Street on the border of Falls Church. It seems an unlikely battleground for the Dranesville District supervisor and the dean of the Northern Virginia delegation to the General Assembly, both of whom represent the area. Each is running for reelection Nov. 3.

A rolling, rustic, two-lane street lined with about 25 houses and towering, lush trees, Haycock Road could be a country road except for one thing that guarantees its prominence. About 500 feet off its shoulder is the West Falls Church Metro Station, which is used by about 4,800 commuters a day. Two of the station's three entrances and exits are on Haycock Road.

Falck believes the road needs to be widened to relieve rush-hour traffic around the station and says that DuVal is fighting the project to appease a small group of people who own homes on the street. DuVal argues that much of the road does not need improvement and that local citizens' groups don't want it widened. Both cite traffic studies they say support their positions.

"I thought nowadays we politicians were supposed to stand tall when there are road projects that need to be done," Falck said. "I am incurring the political baggage of having to tell my constituents that we need a road project that some of them don't want."

DuVal denies that he is catering to the wishes of a few.

"I've been around here three times as long as Falck has," he said. "I'm representing my constituents. There are hundreds of votes on this."

Falck claims that DuVal has used his considerable prestige to persuade state road officials to delay and scale back the project. She notes that the county's master plan calls for Haycock Road to be four lanes and that funds for the $4.6 million project are available. About $1.25 million is from state revenue sharing funds.

DuVal said that residents of the area are concerned that if the road is widened it will cut across their front yards and become a "speedway." In addition, he said, "75 percent of the traffic enters the West Falls Church Station from {an entrance on} Rte. 7."

DuVal said that last month he told state road officials that he would bump the issue to Gov. Gerald L. Baliles if they didn't reconsider scaling back their plans. "It never got that far," he said.

Instead, DuVal said that he has reached an agreement with the state Department of Transportation under which the road will be improved in two stages. The first, to be completed by 1990, would create four lanes for the section of Haycock Road between Rte. 7 and the I-66 overpass that includes the entrances to the Metro station.

The second phase would widen Haycock Road between the I-66 overpass and Great Falls Street "but not until it's needed," DuVal said, adding that that may be more than a decade away.

"The whole project is only blocks long," Falck countered. "I'm an old fat lady and I can walk from Rte. 7 to Great Falls Street. Why disrupt the neighborhood and the Metro station twice when we can do it in one fell swoop?"

The state Highway and Transportation Board is scheduled to consider the project Aug. 20. Falck said if the project is not approved, "I'm going to ask to change the funding, use the revenue sharing funds somewhere else and use county money" to complete the project.