A Montgomery County Circuit Court judge ruled this week that the County Council ignored its own planning laws when it approved a housing development near a congested intersection in Silver Spring by securing a promise from the developer to widen the road there.

Judge James A. McAuliffe Jr. ended a two-year zoning battle launched by the Greater Colesville Citizens Association by ordering the council to deny a rezoning application from DMD Development Corp., which planned to build a 150-unit housing development at the corner of Randolph Road and New Hampshire Avenue.

"This is very unusual," said council member Rose Crenca, who represents the area. "We the council are usually infallible. This sends up a signal that we have to be more careful."

In 1984, the council approved a request from the company to rezone 22 acres of residential property into what is known as a "floating" zone, or property that can be used for different purposes, in order to nearly double the number of housing units that could be built on the land. The council agreed to the rezoning on condition that the development company widen the intersection there.

The complex of town houses and single-family homes, called Nottingham Woods, quickly became the target of protests by the citizens association, which argued that the council had not properly evaluated the amount of traffic there and had no plans to improve the area's congested roads.

McAuliffe, who last year affirmed the council's decision and then recently reconsidered the case, ruled this week that the developer had to improve the roads before building could start. The judge said that under county planning rules the council could not rezone the land until the improvements at the "critical intersection" were completed.

Assistant County Attorney Alan Wright, who argued the case for the county, said yesterday that he did not know whether the council would appeal the decision. If the judge's ruling stands, Wright said, it would "limit the council's ability to rezone . . . and would hamper the developer, who would want to know up front" if property would be available for projects.

Charles Lapinski, president of the citizens association, said that he was "ecstatic about the decision."

"What the judge is saying to the county is: 'There is a body of law here. Enforce it.' "

Jerome Korpeck, attorney for the development company, said he had not yet reviewed the judge's decision but expressed disappointment.

"It's a shame that the corporation can't help the county make road improvements that it the county can't make on its own," Korpeck said. "No one else has plans to improve the congestion in that area."