A construction worker passes through the site of the Wiehle-Reston East Station of the Silver Line Metro rail extension on Tuesday, April 29, 2014, in Tysons Corner, VA.  (Photo by Jahi Chikwendiu/The Washington Post)

Metro could take control of the Silver Line as early as next week, but the final week of May is a stronger possibility, people involved with the inner workings of the project tell the Washington Post. They spoke on condition of anonymity because they are not authorized to publicly discuss the project.

The handover from the Metropolitan Washington Airports Authority to Metro would be the most significant step forward so far in the effort to open the rail line. Officials had originally hoped to begin passenger service last December, but a series of delays has forced them to push that date back to this summer.

Metro officials said they will offer new details on when they will assume control of the Silver Line during a conference call with reporters on Monday. Metro spokesman Dan Stessel said no decision has been made on a handover date.

Once Metro takes control of the project, it will have 90 days to conduct testing and training before it opens the line to passengers. The Tri-State Oversight Committee, which has oversight of Metro’s operations, also will conduct its own safety review. Officials from the Federal Transit Administration must also sign off before the Silver Line opens.

The line is being built in two phases. This first phase will have four stops in Tysons Corner and one in Reston. Work has already begun on the second phase, which will have a stop at Dulles International Airport.

The Silver Line is the first full line to be added to the 38-year-old Metro system in more than two decades. It is also the first not built by the transportation authority. Instead, construction was managed and overseen by MWAA, which hired a consortium led by Bechtel to built the project’s first phase. The second phase will be built by a construction group led by Bethesda-based Clark Construction.

With a price tag of $5.6 billion dollars is it one of the most expensive infrastructure projects currently being built in the U.S.