Montgomery County Executive Charles W. Gilchrist, leading a procession of bankers and businessmen at a public hearing last night, opposed proposals to curb a county building boom, calling them "dubious."

At the same time, citizen groups urged passage of the measures as a short-term solution to "serious and growing" traffic congestion.

The bills, sponsored by council members David L. Scull and Neal Potter, would place a three-year cap on building permits and would prohibit construction of subdivisions until roads serving them are under contract to be built.

The measures are designed to slow the record pace of residential and commercial development at a time when motorists are facing severe congestion on many of the county's major roads and highways.

"We need some breathing room in Montgomery County. We cannot let such serious growth problems drift unresolved," Scull said.

But Gilchrist, testifying at the hearing before the County Council in Rockville, called the measures a "precipitous response" that would cause "substantial and irreparable damage to our . . . credibility and to an orderly development of the county."

At a news conference before the hearing, leaders of seven civic associations representing areas of high growth countered that view and urged the council to pass the measures to gain control of development "during this crisis of congestion."

"We are not opposed to development, we are opposed to a lack of adequate public facilities," said Samuel Crook, president of the Columbia Road Citizens Association, one of the groups.

During the last decade, thousands of new houses and office buildings were approved for construction, but the state and county roads that were supposed to serve them never got off the drawing board because of citizen opposition or a lack of funding.

Because of a shortage of road capacity, more than 70 percent of the county is under a moratorium on new subdivision construction. But the ban does not apply to more than 46,000 houses and 18 million square feet of office space that were approved in prior years.

The cap on building permits is designed to control the pace of construction of those units. Projects approved more than four years before the issuance of a building permit would have to meet current standards for adequate public facilities, according to Scull.

Gilchrist said the cap would present "insurmountable difficulties" in administering building permit quotas, threaten the construction of low-cost housing and create uncertainties that would make it difficult for builders to obtain financing.

Thomas J. Owen, chairman of Perpetual American Bank, one of the region's largest mortgage banks, with more than $850 million in real estate loans extended in Montgomery County, said the measure could stop many of its projects "dead in their tracks."

"We, and most lenders, would have to substantially revise our lending operations in Montgomery County," he said. "Inevitably, many of the county's current developers will be squeezed out . . . . "

County Board of Realtors President Dale L. Ross, representing a coalition of developers and businesses, urged the council to consider enacting a piggyback tax on license registrations and gasoline or imposing fees on new homes to pay for new road construction.

Gilchrist said he also was studying the use of new fees and special taxes to pay for a massive road construction program that is to catch up with the level of development in six years.

Current plans, he said, include $188 million in programmed road improvements to county roads and $300 million in state road improvements. But he said it would take another an additional $100 million in new construction to provide enough road capacity to take care of future development.