Metro took control of the first phase of the Silver Line at 5:30 a.m. May 27.
The milestone, known as the "Operational Readiness Date" (ORD), marked the point where care and control of the line was formally transferred from the Airports Authority to Metro.
From today's date, Metro has up to 90 days for testing and training prior to opening the line for passenger service this summer.
The opening date will be set by the Metro Board of Directors.
When it opens this summer, Silver Line service will run from Wiehle-Reston East station to Largo Town Center, with trains every 6 minutes during rush hour and every 12 to 20 minutes at other times. Five new stations will be added to the Metrorail system: McLean, Tysons Corner, Greensboro, Spring Hill and Wiehle-Reston East.
Work also has begun on Phase 2 of the project, which will connect the Metrorail system with Herndon, Washington Dulles International Airport and points in Loudoun County, Va.