The Reagan National Airport Metro station now has a Train Bridge:
“The ‘Train Bridge’ is Metro’s solution to temporarily out-of-service elevators at the National Airport station. Rather than shuttle passengers who need elevator assistance from the airport to another nearby station, Metro officials decided they could use a train to bridge the temporary gap.
And so, a train bridge is just that — an Metro train riders can use as a pass through to the other platform.”
“The station at National Airport is uniquely configured to allow such a use since it has three tracks. Metro officials simply park the train on the middle track, allowing folks to move easily between platforms depending on whether they’re headed toward Franconia-Springfield or into Prince George’s County.”
— “See Metro’s ‘Train Bridge,’” Lori Aratani, Washington Post