Georgia Avenue from Norbeck Road to just south of Olney's town center is one of Montgomery's rural gateways, a place where the downcounty ends and the upcounty begins.

The blocks of apartment complexes, punctuated by fast-food places and convenience stores, south of Norbeck give way in these three miles to a driving range, a produce stand and tree-shaded single-family homes set comfortably back from the road.

Take a right off Georgia onto Batchellors Forest Road and the transition is complete. There are deer, streams and fields of overgrown grass -- just the way John H. Lyons, an antitrust lawyer in downtown Washington, likes it. From the road, the stone mailbox is the only sign of his home. His white clapboard farmhouse -- with a barn that is home to nine goats, two horses and six chickens -- sits on nine acres at the top of a hill.

But Lyons and others in Olney fear that the rural gateway will become a floodgate if the $2.4 billion intercounty connector from Gaithersburg to Laurel becomes a reality. They say a planned overpass on Georgia north of Norbeck will bring more traffic to an already congested intersection.

"I think the whole area will look and feel more suburban and less semirural," said Lyons, president of the Greater Olney Civic Association. "There will be pressures and arguments to say, 'The ICC is here -- let's take advantage of it.' "

Development defines the downcounty. Luxury condominiums and high-end retail dominate Bethesda, and places such as Silver Spring and Wheaton are well on their way to being revitalized. County planners say that the north is meant to be different. But residents see a horizon filled with threats.

Megachurches, taking advantage of county policy, are buying land in the 93,000-acre agricultural reserve, mostly in northwestern Montgomery. This fall, County Council members will consider a proposal to restrict church construction in the reserve. Northwestern residents also worry that someday a "techway" linking Montgomery and Northern Virginia, debated for years, could be built.

County officials acknowledge that there are pressures pushing development north because the south is virtually built out but say the connector is not a factor. A more northerly route for the road was rejected precisely because of its potential impact on the area's environment and rural character.

Planners say they foresee no circumstances that would cause the county to retreat from its commitment -- as codified in master plans reviewed every 15 or 20 years -- to preserve open space and farmland in the upcounty.

"The development of Montgomery County is guided by our master plans," said Edgar Gonzalez, deputy director of transportation policy for the Department of Public Works and Transportation. "The fact that the ICC is built -- is that going to increase density in Montgomery County? Absolutely no."

Instead, planners said, the connector will ease congestion on roads in residential neighborhoods, make Baltimore-Washington International Airport more accessible to the upcounty and encourage economic development in its own corridor as well as Interstate 270's.

"It really opens that area up, and as a result, makes the upcounty more attractive to larger corporate entities," said County Council member Michael Knapp (D-Upcounty).

In the view of many northeastern Montgomery residents, county plans are far more malleable than Gonzalez suggests. As evidence, they point to the "Golden Bear" area -- named for golfer Jack Nicklaus, who founded a company that bought and sold rights to develop part of the land -- which consists of 85 acres of single-family homes, a driving range and vacant lots near Georgia Avenue and Norbeck Road.

This year, while redoing Olney's master plan, the council agreed to allow denser development in Golden Bear, from one home per two acres to seven units per acre.

A new master plan, adopted by the council in March, redefined the southeast quadrant of Olney to separate Golden Bear from the rest of the semirural area. The fact that the connector would cut off Golden Bear from other parts of Olney made it sensible to treat the area differently, but it was the available land and easy access to bus service that led to the council's decision, said Khalid Afzal, a community planner for the county.

"The Planning Board and the council clearly wanted to make the distinction that they're not upzoning this area because of the ICC," Afzal said.

Much of the housing will be smaller and more moderately priced than other Montgomery homes. It will be built through the county's transferable development rights program, which lets farmers sell their rights to build in the agricultural reserve to buyers who agree to build outside the reserve.

"The upzoning is serving a lot of other county initiatives at the same time," Afzal said.

Nonetheless, the recent discovery of building violations in Clarksburg in northwestern Montgomery has shaken the confidence of some in even the best-laid plans.

"We keep hearing the commitment is solid and steadfast, but we also know there's been such a relaxation of regulations and of a careful, attentive approach to things in general that again, there's a lot of reservations about where the county is going, what the ICC portends," said Stuart Rochester, a Burtonsville resident and chairman of the Fairland Master Plan Citizens Advisory Committee.

"Master plans are written by humans, and as the population increases, master plans can and will be changed," said state Del. Karen S. Montgomery (D-Montgomery), who lives in Brookeville, a town of about 50 homes north of Olney. "I hate to sound pessimistic, but I think it's true."

In Brookeville, Georgia Avenue becomes High Street, a two-lane road. It hits a T at Andrea Barr's 1921 Sears cottage, with one end running through the rest of Brookeville and the other heading to the towns of Sunshine and Unity and on to Howard County.

Barr no longer sits on her patio. The noise and fumes generated by the cars and trucks from Howard, which turn onto High Street bound for the downcounty or the District, drove her indoors.

Each time a big truck passes, her windows shake.

She's afraid to cross High Street to visit her neighbors, some of whose historic houses are cracking from all the rattling. "It's become a truck stop," she said.

Del. Montgomery fears that Brookeville will become even more of a traffic magnet with the connector. For decades, residents have pushed for a bypass to divert traffic away from town.

"If we don't get a bypass built," Montgomery said, "this town will literally get shaken to death."

Kathy Lyons and children Kaylene, 13, Dunchadhn, 9, and Casey, 15, live on nine acres near the connector's path. Lyons's husband, John, says that when the connector is built, "the whole area will look and feel more suburban."Commuters already jam High Street in tiny Brookeville. "It's become a truck stop," resident Andrea Barr says.