A group of developers has made an unprecedented offer to pay up to half the cost for $187 million in road improvements in Montgomery County, if county officials allow them to move ahead with plans to build thousands of homes and offices in the I-270 corridor near Germantown.

New development in the corridor from Rockville to that upper Montgomery County town about 27 miles from Washington is facing almost indefinite delays because of overwhelming traffic congestion on area roadways.

Much of the congestion has come about because rapid development has out paced new road construction, which traditionally has been funded by the government. The situation has grown so acute the county has declared a virtual moritorium on new development throughout the area until it can catch up.

To get around the problem, some developers have formed "road clubs" to pay for small projects to handle traffic created by their particular development. But in this case, more than 30 developers are proposing to create a "super" road club to pay for improvements in an entire region of the county.

"There are other road clubs that usually involve a couple of developers, but this would be unprecedented," said John Menke, director of the county's Department of Environmental Protection. "It raises some difficult policy questions."

County officials have been negotiating with the developers since last August and have come up with their own plan that would divide road improvements into four stages instead of creating "one pot of money" for the projects.

"Basically, it's saying we're not willing to set a road club up for the entire Germantown area but we're willing to do it for a piece of it," said Jeff Zyontz, coordinator of research for the county planning board, which also is involved in the negotiations.

The area in question involves more than 11,000 acres along the I-270 corridor north of Seneca Creek and south of Route 121. The Germantown master plan calls for the construction of up to 35,000 houses and up to 17.7 million square feet of office and commercial space in the area.

To date, about 6,300 dwelling units and 2.4 million square feet of office and commerical space have been built in the area.

Under the county's plan, the first stage of road improvements would be funded with public money and the second stage would by paid for by the developers. Details on projects beyond that have yet to be worked out, said Glenn S. Orlin, a county transportation planner.

The first-stage road projects would include the widening of I-270, the relocation of Route 118 and the widening of Route 355. The projects are designed to help the area "catch up" with current trafffic levels, but would also allow the construction of 11,000 new homes and 2.8 million square feet of office space, Orlin said.

The second stage would include such projects as the constructon of a new, mile-long highway from Crystal Rock Drive to Route 27 that would add a new interchange on I-270. The project and others would clear the way for construction of 5,000 dwelling units and an estimated 11.2 million square feet of office space.

The improvements "would allow development of land on either side of I-270 with commercial and office uses, which would be of tremendous benefit to Montgomery County and the state," said Orlin.

The final two stages of road development would take place some time in the late 1990's and would cover the needs of the rest of Germantown east of Route 355 and west if I-270. The balance of residential growth, 12,700 units, and another 1.3 million square feet of office and commercial space would be reserved for those stages.

Robert McGarry, the county director of transporation, is heading up negotiations with the developers on behalf of the county. So far, the county has not received a response to its proposal, a staff member said.

Patrick McKeever, a lawyer representing the developers, did not return several telephone calls.

The developers' proposal called for the county to pay for the the projects up front, but it did not specify how the developers would pay their share of the costs or how the improvements would be carried out, Menke said.

The proposal also raised questions about whether the developers planned to add the cost of the projects to the price of individual homes.

"Nevertheless, we thought the idea has a fair amount of merit," said Menke. "It's really up to them now to say whether they're interested or not."