After years of inaction by the state of Maryland on the proposed "outer beltway" segment through northeastern Montgomery County, the Montgomery County Planning Board yesterday approved preliminary plans for a subdivision in the middle of the highway's proposed right-of-way.

Planning board members said yesterday that, after six years of postponements, the board could no longer legally prohibit the owner of the 40 acres along the proposed right-of-way from building there.

However, according to Board Chairman Royce Hanson, the action was also designed in part to force the hand of state transportation planners. Unless the county decides that it can acquire the 40 acres itself, the state must either buy the land in the proposed right-of-way, reroute that section of the highway, or scrap all the plans for the 22-mile highway.

If the highway is scrapped, however, it would be a considerable blow to county planners. There is now no major east-west road in northern Montgomery County, and the construction of such a highway could attract a large amount of tax-producing development to the area.

"It was a gamble we had to take," Hanson said. "We can only refuse the owner the right to subdivide his land for three years. We are trying to get the state to accelerate its acquisition program for this road."

In 1964, a complete "outer beltway" ringing the metropolitan area first appeared on planning maps, but since then the original concept of the freeway has been abandoned.

But transportation planners in Montgomery and Prince George's counties still want a high-speed thoroughfare connecting Interstate Rte. 270 and the Baltimore Washington Parkway. Fairfax County planners are also proceeding with plans for similar thoroughfare between I-95 and Virginia Rte. 7. But elsewhere, what was once referred to as the "outer beltway" has been wiped from planning maps.

Montgomery County planners have worked with developers to hold out of use the entire proposed right of way for the "outer beltway" - now known as the - intercounty connector." - The state transportation department also has purchased most of the land for a more southerly connecting route, known as the Rockville facility.

Meanwhile state highway official's have decided to proceed with an environmental and engineering study of the "intercounty connector-rockville facility" project, which if built would cost $262 million at current estimates. The two-year study will begin in September and will consider all possible alternatives routes, and the "no road" alternate.

"There's a definite need for some roadway in a cross-country direction," said State Highway Administrator Slade Caltrider," "and I would like to see something built. But we can make no commitments until the feasibility study is completed."

Until recently, most landowners in Montgomery County have been willing to set aside the right-of-way since they do not have to pay taxes on land that is being reserved for a highway. In addition, development on much of the land has been stalled anyway of an eight-year sewer moratorium.

Now that portions of the sewer moratorium are being lifted in the eastern part of the county, which is considered a prime area development, the planners said they anticipate more problems like the one the owner of the proposed subdivision, Dwight Schar, presented yesterday.

"What it boils down to is that we can no longer protect the right-of-way of the Outer Beltway unless the state comes up with the money," Schar's attorney, Charles Dalrymple told the planning board. "Are we going to have an Outer Beltway or not? That's where we stand."

State Highway Administrator Caltrider said yesterday he could not answer that question. But, he added, "the federal regulations won't allow us to buy land until a project planning study (like the one now under way) is completed, and I can tell you there's not enough state money available [to buy all the right-of-way] without federal aid."

Transportation planners in Montgomery County have promoted the "outer beltway" concept for two main reasons. The Capital Beltway is filled to near capacity at peak hours - particularly from Wisconsin Avenue in Montgomery County to Rte. 50 in Prince George's County. There is also no major east-west freeway connecting the north-south roads and Metro-rail routes through the county.

What Hanson said he fears the most is that no other suitable route could be found for the "intercounty connector" if the current right-of-way is lost. "That could stop development in the prime growth regions of Gaithersburg and Germantown and be the inducement for "low-density sprawl."

"It would be a severe economic loss for the county," Hanson said.