The opening of a new Metro station at Potomac Yard in Alexandria is being delayed at least five months as Metro works out issues with Automatic Train Control systems, the transit agency announced Monday.

The infill station on the Yellow/Blue Line between National Airport and Braddock Road was set to open in April 2022, but now could be delayed until at least September 2022. The station is a key part of the redevelopment of the area, including a mixed-use development, a Virginia Tech campus and nearby Amazon headquarters.

“Metro engineers determined that the original design of the Automatic Train Control (ATC) systems, which was based upon specifications written by Metro, did not meet all of the important safety requirements to ensure the safe operation of trains,” Metro said in a news release. The ATC system ensures trains maintain a safe distance from each other by preventing them from coming too close to one another.

“The need to redesign the ATC system is the result of project management decisions for which Metro is accountable,” the agency added. The City of Alexandria initiated the project to build the station and hired Metro to design, build, and manage the project. Metro hired contractors to physically build the project.

Construction of the station will continue largely on schedule, Metro said, “but there are some track-related construction elements that are dependent upon the completion of the ATC design.”

Both Metro and the City of Alexandria say they’ll work to make up the lost time. Alexandria is hiring a construction consultant to see if there’s a way to expedite the schedule and to determine if there is a way to open the station safely ahead of September of 2022.

It’s unclear what the exact issue is with the ATC system. A Metro spokesperson said they didn’t have any information beyond what was in the news release and referred any other question to the City of Alexandria. The city referred to its release, which said the issue is because of a “contract language decision related to Automatic Train Control specifications.”

“While we appreciate Metro’s acceptance of accountability and recent diligence in addressing this issue, the contract language mistake is inexcusable,” Mayor Justin Wilson said. “With the large investment of $370 million being made by the City and other governmental and private partners to fund the station construction, internal systems should have caught the error.”

Tracy Sayegh Gabriel, Executive Director of the National Landing Business Improvement District, said the BID was disheartened to learn about the delays.

“It is a setback to our steady progress on transportation infrastructure and consumer accessibility,” she said. “The National Landing BID believes that a robust transit system is essential to a thriving downtown, and it is our hope that the delay will be minimized to enable the safe opening of the station as soon as possible.”

The Potomac Yard station is the latest in a series of local high-profile transit delays including the construction of the Silver Line Phase II and Maryland’s Purple Line. Those projects are not being constructed by WMATA but by the Metropolitan Washington Airports Authority and the state of Maryland.

This story was updated to include comments from the National Landing BID.