The Falls Church City Council Monday approved plans for a $6.7 million improvement project on Broad Street (Rte. 7), designed to reduce traffic congestion and beautify the city's main thoroughfare.

The council plans to ask the Virginia Department of Highways and Transportation for $3.9 million to help pay for the project, said Barbara Gordon, city spokeswoman.

The plan accepted by the council calls for the addition of left-turn lanes on Broad Street at the Washington Street, West Street and Haycock Road intersections. The council rejected a more elaborate proposal to widen Broad Street from four to five lanes between West Street and Haycock Road. The five-lane plan was opposed by members of the Village Preservation and Improvement Society and local merchants.

Other Broad Street changes approved by the council include the synchronization of traffic signals, consolidation of bus stops, replacement of curbs and gutters, burial of utility lines, landscaping of the median and sidewalks and installation of new, colonial-style lampposts.

The council rejected a proposed pedestrian overpass at Haycock Road, arguing that it would be too expensive and perhaps underused, Gordon said.

If state highway officials approve the project and there are no financial delays, construction could begin in January 1986, with a May 1987 completion date, Gordon said.