The D.C. Circuit Court of Appeals has granted Maryland a much-needed victory in its effort to build the $5.6 billion Purple Line light rail system, issuing an emergency stay that could allow construction to begin while lawsuits against the project are resolved.

The three-judge panel wrote on July 19 that Maryland “satisfied the stringent requirements” to reinstate environmental approvals revoked by U.S. District Court Judge Richard J. Leon in August 2016. The project has been on hold since then. Maryland sought the emergency ruling last month.

The most contentious issue has been the validity of ridership projections for the 16-mile line in the Washington, D.C. suburbs, particularly in light of declines on the separately operated Metrorail system.

Metro will connect with the Purple Line at four stations in Maryland.

Although Judge Leon subsequently dismissed most of the original lawsuit that sought to block the project on environmental grounds, he refused to allow construction by a Fluor Corp.-led consortium to proceed while Maryland appealed his demand for an updated ridership assessment. Maryland asserted in its appeals court filing that critical decisions about the Purple Line’s future would have to be made around Aug. 1.

The state also raised the possibility of cancelling the project entirely, a move that would cost $800 million.

According to Maryland transportation officials, the protracted legal process had added as much as $13 million a month to the Purple Line’s construction cost, originally set at $2 billion. The delay also jeopardized a $900-billion federal New Starts grant, a program that could see significant cuts in the coming years.

In May, the Federal Transit Administration announced that the Purple Line was one of two transit projects under consideration for funding aid in FY 2018.