Do any trains other than MBTA Needham line trains run anywhere on that branch between Forest Hills and Needham Heights? Is the Millis line beyond the wye at Needham Junction still active or have the rails been pulled up? It's hard to tell on google maps.
The only trains that run on the line are MBTA trains.
The line becomes a rail trail just past Needham Junction through Needham; there are no tracks from there to the Charles River bridge. Rails on and past the Charles River bridge are there but the line is long since abandoned. Dover is fighting over whether to make a rail trail or not.