The proposed I-370 near Gaithersburg, only 3.4 miles long, would be one of the shortest interstate highways in the nation. But it is not short on controversy.

The roadway would provide a fast, nonstop connection between busy I-270 and Gaithersburg's end-of-the-line Metro subway station, due to open in 1984. It would parallel and relieve traffic on Shady Grove Road and permit the extensive development long planned in the area by Montgomery County.

As last week's public hearing on I-370 revealed, some citizens are concerned about the impact of a major highway near existing homes, parks and streams.

But the proposed $114 million, four-to-six lane, S-shaped I-370 won almost universal support from local officials and business groups at the hearing.

The only changes sought include a request by the City of Rockville, which doesn't want I-370 extended west of I-270 (plans show it connecting with Fields Road). And Gaithersburg would like to see interchange ramps moved to take less land from three city parks.

The hearing also raised ghosts of highways past: the dead Outer Beltway and the moribund Inter-County Connector.

"I'm opposed to the Outer Beltway-Inter-County-Connnector-I-370, or as it's otherwise known, the Metro Access Road," Charles Beranek, a resident of nearby Hunter's Run subdivision, told the hearing.

The proposed routing in the Gaithersburg area for all three highways has been virtually the same, and a small amount of land has been bought or dedicated by developers for a major road along that alignment. An Outer Beltway around Washington, however, is a discarded highway plan, opposed by virtually all area officials. And while the 32-mile east-west Inter-County Connector is still officially under study by consultants, most county and state officials discuss it in the past tense. Were it ever to be built, I-370 would be its western leg.

Among I-370's most vocal opponents are residents of the town of Washington Grove, the former Methodist community built in the 1870s and now a registered historic district, and residents of Redland Station and other new subdivisions nearby. They fear noise and air pollution, the road's effect on several streams and woodland, and what they describe as the generally unpleasant prospect of having to live near a busy highway.

Washington Grove Mayor Robert Evans said his community understands the need for major highway improvements in the Shady Grove Road area. But, he said, residents question whether it is necessary to spend $93 million more to build I-370 to handle 10,000 cars a day more than could be accommodated on Shady Grove Road if widened to eight lanes, simply to permit maximum development in the Gaithersburg area and "to fill a 3,000-car parking lot five days a week."

Widening Shady Grove Road, which would cost $22 million to $24 million, is the major alternative to I-370 considered in the 200-page draft environmental impact statement on the highway project.

The existing four-lane Shady Grove Road, which carries 45,000 cars a day and is one of the county's most congested roads during rush hour, will be widened to six lanes this summer. The alternative to I-370 proposes widening it to eight lanes, which would give Shady Grove a maximum capacity of about 75,000 cars a day, about what a six- to eight-lane I-370 would carry, according to George Grandy, state highway project manager for I-370, disputing the figures given by Mayor Evans.

If I-370 is built, however, the combined capacity of the two roads will be 125,000 cars a day or more, says Grandy, adding that this is the only way to accommodate development and Metro traffic long planned for the Gaithersburg area.

Montgomery Planning Board Chairman Norman L. Christeller called I-370, especially the alignment preferred by the state, "a key element of our mass transit and highway plans to support the area's planned commercial, industrial and residential development, much of it west of I-270."

He said planners estimate that I-370 will mean $1 billion in development for the Gaithersburg area, and will bring an additional $30 million in revenues annually to the state, $21 million to the county and $3 million to local municipalities.

Grandy said at least one change in the proposed alignment of I-370 already has been made to swing the road farther away from two streams and the Redland Station community.

Redland residents recently organized a walk along a portion of the I-370 route to show highway officials and others the impact the highway will have, especially on Mill Creek and Crabbs Branch, which are among the headwaters of Rock Creek. Mill Creek feeds directly into Lake Needwood, which has had pollution and silting problems.

Even if the Maryland Department of Transportation approves I-370, the state will not have funds to begin construction for several years, even with the new gasoline taxes approved by the General Assembly to raise additional money for state highway projects. Ninety percent of funds for the project would come from the federal government. Widening Shady Grove Road, were that alternative chosen, also would be built largely with federal funds, which would cover 75 to 80 percent of the cost.

Written comments on the I-370 project received by April 30 will be included in the record the state will study before making a final decision on the road. Comments should be mailed to William Schneider Jr., State Highway Administration, 707 N. Calvert St., Baltimore, Md., 21202.