BOSTON (AP) - Transit officials say the first of a new fleet of Orange Line trains are set to make their debut.

The general manager of the Massachusetts Bay Transportation Authority, Steve Poftak, said Monday that six new trains have been fully tested and will go into service on Wednesday, with more to follow in the coming months.

The MBTA plans to replace the entire existing Orange Line fleet with 152 new trains by 2022.

The rollout was delayed several months in recent times as the T worked to resolve issues around an upgraded signal system.

The T says the new trains will have more spacious interiors, along with wider doors, more handrails, better lighting and safety features including audio and visual warnings that the doors on the train are opening or closing.

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