WMATA placed an initial $US 886m order in 2010 for 428 7000 series cars, and the first pre-series train began trials on the Metrorail network in January 2014. Around 300 of these vehicles will replace the oldest 1000 series trains, while the remainder will be used on the Silver Line to Washington Dulles International Airport and Ashburn. A $US 184m option for 100 additional cars was exercised in May 2013 to replace the unreliable Breda 4000 series vehicles, which date from the mid-1990s.

As well as replacing all of the 1000 and 4000 series trains, the first two batches will expand the Metrorail fleet by 128 vehicles. The trains will operate as four-car units in eight-car formations, which will accommodate 40 more passengers than the trains they are replacing.

WMATA says a second option to purchase a further 220 vehicles "at favourable pricing" is available until the middle of this year and will be exercised if funding can be finalised in time. All of Metrorail's funding sources have indicated that they are willing to support the order.

A second train is currently undergoing tests and is expected to enter service within the next few weeks.

The 23m-long stainless-steel bodied vehicles are being assembled at the Kawasaki Motors Manufacturing facility in Lincoln, Nebraska.