The Prudential Insurance Co.'s real estate division is proposing to spend an unprecedented $11.5 million for new road construction and improvements in an effort to win approval to build a major subdivision in the traffic-clogged Germantown area.

However, the Montgomery County Planning Board told the developers recently that a more detailed traffic study is needed of the area fed by Maryland Rte. 118, I-270 and Middlebrook Road before planners can determine whether the 1,239 housing units Prudential wants to build there would generate more traffic than is allowed under county guidelines. Of that total, 382 town houses and garden apartments have already been approved.

If the Prudential development is approved, it will be the first new project approved by the planning board since a moratorium in the Germantown area went into effect about four years ago, according to planner Charles Loehr.

During the moratorium, no building permits for new projects were issued, although plans "already approved and in the pipeline" were allowed to go forward, transportation planner Bud Liem said.

The freeze on projects was designed to allow construction of roads, schools and services to catch up with northern Montgomery's housing boom. But now the pace of development, especially in the area north of Rockville, has become an intensely debated election-year issue.

Planners said Prudential's $11.5 million transportation fund marks the first time a single developer has agreed to take on such significant road construction projects. In order to win approval for other projects, some developers have pooled financial resources in so-called "road clubs." But Liem said, "We've had nothing of this magnitude before."

Loehr said, " . . . The only reason it might go forward is because Prudential is offering a very, very substantial roads package . . . ; we're talking big bucks."

The four Prudential subdivisions are part of Germantown's planned town, which includes six villages, an employment center around I-270 and a ring of parkland.

When completed, the town would be about the size of the town of Columbia. The Prudential project is known as Water's Landing and is part of the Churchill Village town plan, planner John Mathias said.

Under the proposal, the developers have agreed to widen Middlebrook Road to four lanes from Great Seneca Highway to I-270; construct four-lane Crystal Rock Drive from Rte. 118 to Germantown Drive; widen Germantown Drive to four lanes, and widen Wisteria Drive to four lanes.

About $6.5 million will go toward these road projects, with the remaining $5 million going into a discretionary county transportation fund, developer Morton H. Levine said. Levine's group, Associated Investment Co. Inc., is representing Prudential in hearings before the planning board.

Transportation studies indicate that if the roads Prudential proposes to build are built on time, then traffic along Rte. 118 in Germantown will be no worse than it is at present, and slightly better than it would be without the new roads at some intersections, Liem said.

Complicating the planning board's discussion was the fact that a county law passed in April requires that road projects in a local planning area have money already appropriated for them before development can occur nearby.