The closure blocks the center lane in each direction on 17th Street Northwest, between I and K streets, Metro said in a statement late Friday.

The center lanes of 17th Street Northwest near D.C.’s Farragut Square are closed over concerns identified Friday about whether Metro ventilation shafts under the roadway are structurally sound enough to support traffic on the downtown artery.

The closure from Metro and the District Department of Transportation blocks the center lane in each direction on 17th Street Northwest, between I and K streets, Metro said in a statement late Friday night. It’s where drivers typically go over grates that lead down to the Red Line.

“During a structural inspection, engineers identified concerns with the structure’s cross beams that support vehicle weight. In response, Metro requested that the two center travel lanes — one northbound and one southbound — be closed until further notice as structural repairs are made,” Metro said.

To keep traffic backups from building up too much, DDOT has instituted emergency no parking rules in the closure area, so two lanes will remain open in each direction.

Metro didn’t say how long fixing the issue would take, but the closure could last for an extended period.

“Construction contractors are in the process of being acquired by Metro on an expedited timeline, and Metro will update the public regarding the duration of the lane closures as soon as a project schedule is known,” Metro said.

Below is a map of the area of the closure.