When Orange Line trains start running between Oak Grove and North Station Saturday, the MBTA says the entire line will run at full speed.

“That will be the first time the Orange Line is restriction free in 15 years,” MBTA General Manager Phil Eng said during an appearance at the Greater Boston Chamber of Commerce on Wednesday.

The reopening marks a significant piece of progress in the T’s ambitious track improvement plan. The effort began last November with a series of closures aimed at lifting nearly 200 speed restrictions across all train lines by 2025. Eng said Wednesday that he is confident the agency will make the entire system speed restriction–free by the end of the year.

As of Friday, the Blue Line is already running at full speed across the entire line. Trains on the Blue, Red and Orange lines are all faster than they were last year and have increased the number of daily round trips, according to trackers maintained by the transportation advocacy group Transit Matters.

The next phase of track maintenance work begins next week on the Red Line. The agency has also announced several disruptions coming to the Green Line and Commuter Rail.

During each of the shutdowns, the MBTA will provide alternative service. The MBTA is also encouraging riders to take Commuter Rail when possible.

Red Line

  • Nov. 5-10: No train service between Broadway and North Quincy. Free and accessible shuttle buses will make all stops.
  • Nov. 9-10: No train service between Broadway and Ashmont. Free and accessible shuttle buses will make all stops.
  • Nov. 18-24: No train service between Harvard and Broadway. Shuttles will make all stops between Harvard and Broadway, with the exception of Park Street and Downtown Crossing.

Green Line

  • Nov. 9-10: No train service on the D branch between Riverside and Kenmore. Free and accessible shuttle buses will make all stops.
  • Nov. 11-17: No train service between Union Square and Lechmere. No shuttle service. MBTA advises riders to use bus routes and the Orange Line.
  • Nov. 15-17: No train service between Park Street and Union Square, as well as East Somerville. Free and accessible shuttle buses will make stops between North Station and East Somerville, but will not service between North Station and Park Street.

A full list of service changes can be found here.