The Massachusetts state GIS group has the RoW in their rail layer as "GISDATA.TRAINS_ARC.4824", and it's
viewable in their OLIVER tool.
Screen Shot 2018-03-17 at 6.08.42 PM.png
I can't find a way to turn off the 3D trees in the web version of Google Earth, but if you use the real Earth app the other two bridges are really easy to spot because of the shadows they cast!!
This one is at 42.45744967538994,-71.1056615607615:
42.45744967538994,-71.1056615607615.png
...and the other is at 42.45964876615285,-71.10439011309818:
42.45964876615285,-71.10439011309818.png