Drive down Telegraph Road in southeast Fairfax County and you'll see why some Northern Virginia Republicans say state Del. Gladys B. Keating (D-Fairfax) could be vulnerable in her quest for a fifth term in the General Assembly next year.

The bulldozer is king in Keating's 43rd House District. Springing up throughout the mainly working class area, which encompasses the Lee District, are developments with names like Willow Creek and Woodfield, selling at prices higher than average for the area. Kingstowne, a $600 million minicity of homes for 15,000 people, is scheduled to be built there.

Four thousand new voters have registered since 1983, a 20 percent increase. And state Republican Party officials say those new voters -- many of them younger and richer than longtime area residents -- are GOP sympathizers.

Keating, 62, who stresses her consumer activism, experience and advantage of seniority, is being challenged by Edith L. (Edie) Stratton, 54, a Republican activist who says Keating is out of touch with those new voters.

"I'm just going to have to go after them and stress the importance of retaining a senior delegate from the area," Keating said.

"We have an awful lot of younger people and they are conservative to moderate," Stratton said. "I feel I can better represent them."

One indication of the seriousness of the contest is that both sides are spending more than usual. Keating, who spent $5,000 on her first winning campaign in 1977, expects to budget $30,000. Stratton, whose local fund raising is being supplemented by extra help from the state party, plans to spend $48,000.

James S. Turpin Jr., executive director of the Joint Republican Caucus, said state GOP officials are "guardedly optimistic" about Stratton's chances. Stratton has a long record of civic activism and involvement in other Republican candidates' campaigns.

She attended the University of Kentucky, Morehead State University and Northern Virginia Community College, and lists her occupation as property manager/housewife. Her campaign material advertises her as a "mother of two, grandmother of three."

Keating attended four different colleges and universities, including George Mason and the University of Virginia. Also active in local civic and church boards, she served for four years as vice president of the executive board of the Virginia Citizens Consumer Council.

In an interview at her home, Stratton did not cite many specifics of legislation she would sponsor, but said transportation and crime are key issues in the district.

She supports the proposed Springfield bypass and the Lockheed-Van Dorn connector, both part of the proposed $135 county road bond referendum on the Nov. 5 ballot. And she promises to fight to keep the additional road funds won for Northern Virginia last session by the area delegation, which included Keating.

Stratton also promises to work for state money for a Northern Virginia commuter rail system, which Keating also supports, and favors mandatory jail terms for drug-related crime.

The Republican candidate said she is not certain how she would vote on the Equal Rights Amendment, should it come up again before the General Assembly, which defeated it in the past.

Stratton criticized Keating's abstention on a 1983 bill that would have returned more state liquor store funds to the district. The liquor fund return is based on population, currently revised after the Census every 10 years. The proposal would have revised the count every year, an advantage for the fast-growing district.

Keating said that issue came up in her last campaign, and her answer is that she abstained in a political deal to win $21 million in new money for Metro -- far more than the district would have gained in increased liquor funds.

Keating, interviewed in her wood-paneled office in the basement of her Franconia home, said one of her arguments for reelection is that "seniority is so desperately important," particularly when Northern Virginia delegates are up against Tidewater representatives who get elected year after year.

She cites two bills as her biggest successes. One allows local officials to decriminalize zoning violations to solve such problems without giving someone a criminal record. The other lets localities relocate or take care of abandoned graveyards, many of which have been desecrated.

She also sponsored a bill allowing judges to divide pensions when a couple divorces, and pushed legislation promoting cellular telephones and paging services.