The Arlington County Board will hold a public hearing Sept. 24 on a proposal to build a vehicle overpass over Route 50 in the vicinity of Highland Street.

The project, proposed by the Arlington Department of Transportation, is opposed by civic groups representing the neighborhoods of Lyon Park, Arlington Heights and Ashton Heights.

If approved, the overpass would carry traffic between the north and south sides of Route 50.

"Traffic will be restricted. It is not intended to be a commuter facility," said John Hummel, chief, planning and engineering division of the Arlington department of transportation. He said there would be one ramp on each side of Route 50 connecting service roads which would lead into the streets of the neighborhood and to the overpass.

But residents contend that there will be more air pollution, more accidents and more traffic in their neighborhoods, according to Frank O'Leary of the Lyon Park Civic Association. O'Leary called the overpass "totally injurious to neighborhoods" and said that "Highland Street which now haszero to one accident per year is a residential street, not designed to carry that much traffic."

County Board member Dorothy Grotos said, "I know the majority of the citizens are against it (the overpass). They are out getting petition signed.

The Lyon Park Civic Association is circulating petitions on the north side of Route 50 while Arlington Heights Civis Association is circulating petitions on the south side, according to O'Leary.

Longbranch Elementary School Principal Celez Nitkowski said she felt "construction itself will pose us problems. It will be a safety hazard for children. The children from Jackson to Fillmore (streets) are all walkers and there are a large number."

But according to Hummel, the overpass would be "safer for children" because "less traffic would use Fillmore" the street on which Longbranch school is located.He said there would be no vehicle access directly from the neighborhood streets into Route 50 except at the point of the overpass.

The overpass is part of a 20-year plan for highways within Arlington adopted by the Board in November, 1975, according to Hummel. The overpass would be funded by the state, Hummel said, but he "doesn't believe the state would overrule the Board's decision because they regard it as a county matter."

County Board Chairman Joseph S. Wholey said, "There may be an overpass needed to serve the immediate neighborhood. The people are frightened it will be a major highway, but the Board has already decided against that."

"What I am concerned about," said Grotos, "is that the overpass is just the beginning." She said the overpass "is not just to serve the neighborhood, but to serve Metro. Everything has to be bent to serve Metro. I really though Metro was going to serve us."

The Claredon Metro station will be located at North Highland Street and Wilson Boulevard, as hort distance from the Route 50 proposed overpass.

Hummel said the transportation department plans to restrict commuter traffic from leaving Route 50 and using Highland Street to go to the Metro Station during rush hours.

Grotos said she had not definitely decided how she would vote on the issue. "But," she said, "I want to protect Arlington. I am not willing to sacrifice Arlington. I think we should try to preserve it as a residential neighborhood, but maybe that's not realistic."