The MBTA plans to shut down Orange Line service between the Sullivan Square and Tufts Medical Center stations for six consecutive upcoming weekends, with the first closure scheduled to begin Friday at 8:45 p.m.

T officials plan a 3:30 p.m. event at the line's Downtown Crossing station, on the northbound Oak Grove-bound platform, to discuss work scheduled to take place at that station and the Haymarket and State stations during the six weekends.

The work includes replacing and adding signs, cleaning, painting, and making repairs to stairs and tiles. The extended closures will also be used to make repairs to escalators, elevators and fare equipment, according to the T, and to perform maintenance work in the tunnels between the stations, including the complete replacement of third rail insulators and third rail electrical connections.

Crews also plan to replace 2,250 feet of track within Chinatown Station, which will also be cleaned and painted. The closures will enable the T to wrap up the work a year earlier than previously planned.

During the six weekends, bus shuttles will be provided between Sullivan Square and Haymarket stations. There will be no shuttle bus service to Orange Line stations at State, Downtown Crossing, and Chinatown with customers asked to travel via parallel downtown Green Line service.