A controversial half-mile extension of the Little Falls Branch Parkway bicycle trail -- held up by a federal court injunction for more than 16 months -- will now be built "as swiftly as we can move on it," Royce Hanson, chairman of the Maryland-National Capital Park and Planning Commission, said this week.

The go-ahead came this month when U.S. District Court Judge Oliver Gasch dissolved the injunction he had granted in the spring of 1978 to some residents of the Westmoreland Woods section who opposed the bike trail.

A two-mile trail already is being constructed along Little Falls Branch Parkway between Bradley Boulevard and Massachusetts Avenue. The new section of bike path will extend the trail south of Massachusetts Avenue to Albemarle Street on top of or beside a newly reconstructed sewer line. The Washington Suburban Sanitary Commission set aside funds for the bike trail as part of its sewer project. The new section will be paved this fall, if weather permits, or early next spring, according to Robert Haven, WSSC director of engineering.

The residents, who formed a group called Save the Westmoreland Woods Inc., complained that an inadequate environmental study had been done on the bike trail's potential impact on the quiet, woodsy parkland east of Massachusetts Avenue. They also contended a bike trail would bring large numbers of people and increased crime to county parkland that now is undeveloped and relatively unused by county residents.

Gasch ruled that subsequent studies by the WSSC and the National Capital Planning Commission have found the bike trail will have little adverse environmental impact and that bike trails have not brought crime to other areas.

The judge rejected as premature the neighbors' request for an injunction against a further extension of the bike trail, from Albemarle past the Dalecarlia Reservoir to MacArthus Boulevard, because the county has not yet developed specific plans for a trail there. Hanson said the county will need permission from the Army Corps of Engineers to pass near the reservoir. n