The fate of the planned 16-mile Purple Line light-rail project across Washington, DC’s Maryland suburbs has been clouded by a federal court’s call for an updated environmental study—adding another delay to a project already on the brink of losing nearly $1 billion in federal funds.

U.S. District Judge Richard J. Leon ruled on May 22 that Maryland and federal transit officials “failed to take the requisite ‘hard look’” at how Purple Line ridership might be affected by the recent spate of infrastructure and safety issues on the region’s separately operated Metrorail system.