Purple Line advocates applauded a federal judge’s decision to dismiss most of a lawsuit seeking to block construction of the $2 billion light-rail project in the Maryland suburbs between Bethesda and New Carrollton.

Purple Line Now, a coalition of business, labor, environment, neighborhood and civic organizations in favor of the light-rail project, said in a statement on its website that “The appeal now offers a clear path forward and we ask that the state continue funding the Purple Line throughout this process to avoid a costly slow-down.”

The ruling, issued Tuesday by U.S. District Court Judge Richard Leon, stated that the state of Maryland’s environmental review of the proposed project did not violate federal protections on endangered species and migratory birds.

Hours after the ruling, the state of Maryland appealed the final element of the lawsuit—a court order to revisit ridership forecasts that the plaintiffs claim assumes higher Metrorail usage numbers. Meanwhile, Maryland and federal transit officials have said that subsequent analysis shows that declining Metrorail ridership would not significantly affect the Purple Line.

The Purple Line would be operated independently of Metrorail, which is run by the Washington Metropolitan Area Transit Authority—although passengers would be able to transfer between the two systems at Bethesda, Silver Spring, College Park and New Carrollton. Two Chevy Chase residents and a trail advocacy group filed suit in 2014 seeking to block the proposed project due to environmental concerns.

The ruling and impending appeal come at a precarious time for the project, as it seeks $900 million in federal construction grants to defray the $2 billion price tag.