The article was just updated to say that BEMU service would begin by the end of 2027.
Still seems like a short timeline but it is roughly in line with Metra's timeline for their BEMUs .
https://mass.streetsblog.org/2024/03/16/mbta-plans-frequent-running-battery-electric-trains-on-the-fairmount-line
20 min weekday & 30 min weekend service on the Fairmount line by 2026?
It seems like everyone's dead set on these battery powered trains which I still don't totally understand but...
It feels like adding a couple stops on the Fitchburg line and buying some DMUs would be a lot easier than another green line extension. This project does look great otherwise