A quirky bit of the T is the High speed trolley line from Ashmont to Mattapan with 70 year old PCC cars. Intended as a "trolley freeway" now lives on as a link to Ashmont from Mattapan.
A set of 01600 cars built in 1970 cross the peak of the Longfellow Bridge. These are due to retirement as the new CRRC cars come on line. This bridge was recently rebuilt in the last years.
The newest cars on the T built by Chinese firm CRRC rolls off of the Longfellow Bridge from Cambridge into Boston. These much delayed cars will eventually replace the entire Red Line fleet.