The residents of Clarksburg in upper Montgomery County got their very first traffic light this spring. By the end of the 1990s, they'll be getting an entirely new town.

Working with urban planners from the county government and developers who control much of the land in the area, the 1,500 people who call Clarksburg home are on the leading edge of the long process that will transform their rolling hills and farmlands into a large suburban community packed with retail shops, glass offices and houses of almost every variety.

Meeting nearly every week to determine the shape of the new Clarksburg, residents and county planners grapple with issues ranging from the everyday -- street patterns, storefront locations and the like -- to the more theoretical concerns of proper population densities and desired mixes of residents.

In the process, Clarksburg has become a laboratory for suburban living, as Montgomery's planners question the old ways of creating communities where residents are so often dependent on cars and the center of activity is often a shopping mall. Clarksburg, say county officials, offers a rare chance for planners and others to demonstrate what they have learned from mistakes made in other modern-day communities of Montgomery County.

The stakes in this line of work are high, for not only can planning mistakes be costly, spoiling the landscape for decades to come, they have the potential of upsetting a community's whole equilibrium if jobs, houses, schools and roads are forecast incorrectly.

"The problem is trying to plan in the 1990s, with a 1990s marketplace, for a world that is years out into the future," said Lyn Coleman, who heads the team of more than 12 people planning Clarksburg for the Maryland-National Capital Park and Planning Commission.

No significant amount of construction is expected in Clarksburg for several years, given the recent slowdown in the Washington area's housing and office markets. But few dispute that its social and economic character is about to undergo a radical transformation.

Just east of Interstate 270 about 20 miles north of Washington, Clarksburg stands as one of the last preserves of open space in a metropolitan region that has experienced extraordinary growth in the last 30 years. Architects of growth plans for the region envisioned development springing up in small clusters along major transportation routes spoking out from the core city, the District.

To varying degrees, suburban jurisdictions in Virginia and Maryland have adopted this general blueprint, using interstates such as Routes 66, 95 and 270 as magnets for growth. None, though, have followed the regional plan more stringently than Montgomery County, whose planners designed corridor cities along the I-270 spine. First came Rockville, then Gaithersburg and most recently, Germantown -- three communities with a combined population of 200,000.

Now the final bead is about to be placed on that strand: Clarksburg.

That new Clarksburg may bear striking resemblances to the old. Some residents involved in planning the new community would much rather see the town take on the flavor of a Georgetown or an Old Town Alexandria rather than that of a typical suburban community. Some community activists said they also want a return to the traditional grid pattern of streets, not the conventional winding roads and cul-de-sacs of suburbia. Others said they want storefronts pushed right up to the street, not set back behind parking lots or bunched up in strip malls.

"A lot of people are losing their love affair with the car," said Jeane Onufry, president of the community group working with county planners. "With cul-de-sacs, it makes it hard to walk anywhere because the streets don't go anyplace. They just dead end."

That concept meshes well with a key goal of the county planners: creating a 21st-century city that is far less reliant on the car than most communities are today. Studies show the typical U.S. household makes more than 10 car trips a day, up from four daily trips in the 1960s.

If Clarksburg is to help change the American dependence on the automobile, the town will need to have a fairly significant clustering of residents near its center, urban planners believe. That way, planners say, more people will be prone to walk to shopping or to use the light-rail train that one day may run from the center of Clarksburg to the Metro stop on the Red Line at Shady Grove.

As planners see it now, the town center would be formed from an intermingled collection of housing, retail shops, offices, green areas, churches and civic facilities such as a post office and library.

"We have been adamant that we do not want the center of town to be a shopping mall," Onufry said.

However, what that vision of Clarksburg has in aesthetic appeal it may lack in practical application.

Developers argue that, like it or not, most homeowners in communities such as Clarksburg would rather get in their cars to run errands and prefer to live on cul-de-sac roads far off main thoroughfares.

"No matter how you try to cut, turn and twist it, you're in suburbia -- you can't turn it urban," said Morton Levine, whose Bethesda-based development firm, Associated Companies, owns about 500 acres in the Clarksburg area.

The apprehension some Clarksburg residents say they hold about the new town stems in many ways from their view of Germantown, Montgomery County's most recently developed corridor city. To some residents of Clarksburg, Germantown is the ugly cousin to the south, a sea of look-alike town houses interrupted occasionally by a drab-looking strip mall.

"A lot of people use Germantown as the example of what they don't want Clarksburg to become," Onufry said.

According to county demographers, 17 percent of the dwellings in Germantown are single-family detached houses. The rest are town houses or apartments. Although there are plans for a town center, that process was slowed by the emergence of several "village centers," or strip malls, that were built during the last decade.

"The same people who designed Germantown unrealistically are designing Clarksburg," complains Karl Spain, until recently the president of the Germantown Chamber of Commerce and a participant in the revision of the area's growth plan. "If the residents {of Clarksburg} are awake and listening, they'll make sure they come visit the people in Germantown and find out what went on here."

According to county officials involved in the planning of Germantown, the community's identity was shaped in many ways by economic forces too overpowering for the county to control.

The original design called for a much wider variety of housing than now exists, a town center that would serve as the focal point of commerce and cultural activity, and villages whose streetscapes and other appointments would give them each a distinct identity.

But as building in Germantown started to peak in the early 1970s, the economy was in a slump, interest rates were high and several builders were falling into bankruptcy. Consumers sought housing bargains, and developers responded by pressuring the county to change the zoning in some areas to accomodate more town houses, which are cheaper to build and more appealing for budget-conscious homeowners.

"I think the Planning Board made some mistakes, but there were market forces at work that were difficult to control," said Norman L. Christeller, who was chairman of the Montgomery County Planning Board during much of Germantown's growth.

Christeller said he also felt pressure from residents and developers to allow the strip malls to develop in ways that were contrary to the plan for the town center. "The people in Germantown would have lynched me if I didn't allow a shopping center," he said. "We said it didn't fit with the plan, but they wanted it in."

Defenders of Germantown describe the community as a gangly child: only halfway through its development, with years of refinement still before it. A more diverse housing mix will come, as will the town center and other features that give a community its character, some community leaders say.

Nonetheless, Clarksburg's development will be different, in part because of the lessons learned in Germantown.

"As one planner said, 'We can always get smarter,' " Coleman said.