The Montgomery County Council unanimously approved a 126-page plan to guide development Tuesday, ushering in a new era of denser development for the prosperous Maryland suburb of Washington, D.C.

The plan, called Thrive 2050, has been in the works for years and garnered controversy along the way for its proposal to add duplexes, triplexes and other forms of dense development in neighborhoods previously zoned for single-family homes, the Washington Post reports.

The plan drew praise from smart growth advocates who said additional density — particularly in the eastern portions of the county, near transit — is necessary to meet the housing goals set by the Metropolitan Washington Council of Governments and the county itself.

Last year, outgoing County Council Board Member Hans Riemer told Bisnow the eastern portion of the county had been "left behind" by the 1964 master-planning document the county was still using. He said Thrive 2050 could unleash greater density in future master plans for individual communities in Montgomery County.

"It will give the Planning Board more flexibility to consider different options as they move forward," Riemer said. "I think they've felt constrained in what they can consider."

The plan lists several key objectives, including racial equity, social justice and environmental resilience. It specifically seeks to avoid sprawl by emphasizing diverse uses and building types, including in transportation centers like Silver Spring, Wheaton and Glenmont.

That development is funneled through growth corridors along major public transportation routes like Metro’s Red Line and Maryland’s Purple Line, but the plan also allows for lower-density transit and population centers along various major arterial roads throughout the eastern and western portions of the county.

That added density earned some of the strongest complaints from residents, who said they were worried about traffic and public safety. Ultimately, though, board members said the document was “the beginning, not the end” of conversations around how to build density for a growing population, Council Member Sidney Katz said, according to the Post.

County Executive Marc Elrich — who won the primary in his re-election campaign this summer by 32 votes — was among the plan’s critics who made an eleventh-hour case to delay Thrive 2050’s implementation because the county’s entire planning board was forced to step down last week.

The board has been caught up in an evolving scandal since former planning board Chair Casey Anderson was docked pay for sharing alcohol from a bar in his office with other employees. A later complaint alleged he used misogynistic language in meetings. After Deputy Planning Director Gwen Wright defended him publicly, she was fired, prompting the county council to expand an investigation into Anderson to include Wright’s firing.

The council unanimously asked for all five members’ resignations. Council members interviewed candidates Tuesday and are expected to vote on new planning board members in December after the new council slate is sworn in, according to the Post.