Montgomery County is about to impose a building moratorium aroung Gaithersburg because traffic is clogging the areas state roads and the state has no money to imporve them, county Planning Board Chairman Norman L. Christeller said this week.

The board already is limiting the size of housing subdivisions around Gaithersburg, one of the fastest-growing areas in the county during the past decade. At a meeting today board members are expected to deny preliminary plans to subdivide an eight-acre industrial development in the Germantown section north of Gaithersburg.

Christeller said he could not comment on the project before tonight's board meeting, but said that "our very good program to attract business to the county is now somewhat in jeopardy" because of "a hell of a big backlog of state road projects. The state is many years behind," and the delays in development could cost the state and county millions in lost revenue.

The Mobil Corp. announced two weeks ago that it was dropping plans for a $360 million development of an office, commercial and hotel complex on the 212-acre site now occupied by the Washingtonian Country Club along I-270 south of Gaithersburg, primarily because of the inadequate road system in the area.

The Mobil development, now rumored to be going to Fairfax County, would have provided $70 million in annual revenues and as many as 10,000 new jobs.

Transportation improvements planned in Montgomery do not "fit into our timetable for development," a Mobil official said.

In particular, Mobil cited the lack of firm plans to build I-370, the highway that would link the country club with I-270 and the new Metro subway station due to open in 1983. I-370 would be the western end of the Intercounty Connector, if that road is ever built. Public hearings are to be held on plans for I-370 this winter but there are no state funds to build it. The earliest it could be completed is 1985, even if it were funded, county planners say.

The planning staff is recommending against developing the eight-acre industrial site, on Middlebrook Road off I-270 north of Gaithersburg, because the roads will be "inadequate to handle the traffic," according to Highway Coordinator Edward Ferber. The developer, Brook Venture, is proposing a building of approximately 100,000 square feet which would be ready for occupancy in 1982 if approved now.

County officials estimate the development would add 115 cars to rush-hour traffic, dropping the level of service on the road to "E," said Ferber. Under traffic engineering standards, "E" service means "delays are significant . . . (and) congestion exists for extended duration throughout the rush hour."

Not only are many intersections around Gaithersburg already at level E, says Ferber, but developments already approved but not yet built on Middlebrook Road and in other areas could increase traffic on many other roads, also bringing them to level E. A 1973 county ordinance prohibits development in areas that lack adequate public facilities such as roads, and level E is definitely inadequate, said Ferber.

"I guess this is like the sewer moratorium of the 1970s," county Planning Coordinator John Matthias said last week. Montgomery had a countywide sewer moratorium that stopped housing construction in the mid-1970s because the Blue Plains Sewage Treatment Plant could not handle any additional county sewage. "Now the roads cannot handle more cars," Matthias said.

Christeller, County Executive Charles W. Gilchrest and County Council members have been making pilgrimages to Annapolis to push for Gov. Harry Hughes' proposed 4 percent tax on the wholesale price of gasoline and higher truck fees, which would produce more than $400 million for highway and bridge projects around the state over the next five years.

Even if these measures are approved, however, "there's no assurance Montgomery will get the money" it needs for crucial projects around Gaithersburg, like I-370 and Rte. 28, which Christeller said are the two most important highway projects in that area.

The city of Gaithersburg, which has its own planning and zoning authority, has imposed no limits on development, "but we agree with what the county is doing" in curtailing growth, says Assistant City Planner Trudy Walton. "We've been saying for years that the roads are not adequate for the subdivisions being approved" in the county.

Although almost half its land is still undeveloped, the city has had relatively little development lately, Walton said, because high interests rates have stopped most housing projects dead in their tracts.

The picture isn't entirely gloomy, city and county planners say, because the county is spending some of its own money on state roads -- an unheard-of action 10 years ago, says Christeller -- and a number of developers now are offering to pay for public road improvements in exchange for approval of their projects.