Last year saw important milestones of the Central Subway project, including the reopening of Stockton Street through Chinatown and Union Square as well as some of the major final touches to the stations like escalators and public art.
Mass. Electric will focus on core system, safety elements, including all necessary power, signaling and communications equipment.
In the coming months, agency will be updating the design specifications for streetcar vehicles.
The new rail is half the weight of the old and conducts electricity better.
The first subpoena sought records that date back to the early days of the project.
The massive reconstruction work, announced in 2016, called for a full closure of the tunnel for 18 months.
Projects include the Tempe Streetcar project in Arizona; and the Los Angeles Westside Purple Line Section 3 project.
The three-mile streetcar, scheduled to open in 2021, includes 14 stops and two Valley Metro light rail connections.
A planned four-mile streetcar system would stop at key downtown Los Angeles stops.
Will use extended shutdowns during summer months-rather than single tracking-to provide 24-hour access to work sites.