Montgomery County may be forced to impose a moratorium on development at one of the county's prime sites because the roads and highways there are inadequate and the state is running short of money to improve them.

County officials say delays in state highway construction and maintenance threaten to halt development around the intersection of Shady Grove Road and I-270. Such a moratorium would be a serious blow to the continued economic development of the county, which now is engaged in something of a bidding war with Fairfax County for some national corporations looking to locate in this region.

The problem, according to both county and state officials, is that the State Highway Trust Fund, which pays for at least part of the construction and general upkeep of Maryland's roads, is a dwindling pot, hard-hit by inflation and escalating road construction costs. State officials already have had to reduce their outlays for road projects by 40 percent across the state, according to State Highway Administrator Slade Caltrider.

In testimony last week before a transportation oversight committee in Annapolis, County Planning Board Chairman Norman L. Christeller spelled out the county's dilemma in no uncertain terms.

"We currently face a development crisis in Montgomery County," he said. "Within a few weeks, in the absence of corrective action, the planning board will be required by law to disapprove further development applications near the hottest economic development corridor in the state, the I-270 corridor."

It was the same message County Executive Charles Gilchrist carried to Governor Harry Hughes in late August, and to underscore his case he took with him the executives of six major corporations who want to locate or expand around Shady Grove.

The funding squeeze has prompted county officials to call for an increase in the state's gasoline tax, the primary source of revenue for the highway trust fund.

Attempts to raise the gasoline tax are a drama that has been played out before in the halls of Maryland's statehouse, and politicians have in the past proved unwilling to vote for a gas tax rise in an election year.

So far, Montgomery County has been able to avert a development moratorium by using its own money to pick up the tab for a number of state projects. County Transportation Department Director Gerald R. Cichy said the county is paying to improve the interchange at I-270 and Shady Grove Rd. -- to the tune of $500,000 -- and also is using its own money to widen some sections of New Hampshire Avenue, Georgia Avenue, and Rte. 28 west of Rockville.

"These are roads that are state responsibility," Cichy said. The county-funded road projects will not be as extensive as if the state had paid the bill, but local officials decided to go ahead, he added, "just because of the economic development."

Montgomery recently added $10 million to its capital improvements program to fund those road projects, but according to Thomas B. Stone Jr., special assistant to County Executive Charles Gilchrist, "We've absolutely reached the point where we cannot add anymore."

A 1973 county ordinance prohibits any new development unless existing public facilities -- like roads and highways -- are adequate to sustain the development. Existing road facilities in the Shady Grove area now are saturated, and if the county does not get more money the planning board would be forced to reject or hold up all applications for development there, and possibly in other areas with inadequate roads, at a time when several corporations in the county are planning to expand and other firms are looking to locate there.

One affected project would be Mobil Oil Corp.'s proposed multimillion development partly on the site of the Washingtonian golf course on I-270. Mobil's proposed combination office, hotel, retail and residential complex is expected to bring the county as much as $70 million in tax revenues over the 10-year course of its construction.

"The problem with the State Highway Trust Fund is that it throws a monkey wrench into future road plans," said Robert B. McLean, search manager for the Mobil Land Development Corp. "We can't develop anything without further road construction."

Mobil's project still is in the planning stages, and the county is afraid that further delays in road construction might prod the company to look elsewhere. McLean said, "We are also looking in Virginia to purchase property there, but who knows?"