Source URL?
So I googled it.
Here is the official policy of massDOT (Massachusetts Department of Transportation): Only tripods and equipment that can disrupt foot traffic are prohibited on train platforms. No permission is required for non-commercial photography (e.g. images taken by tourists, railroad buffs, students, artists). Any person wishing to take images for commercial purpose must first obtain a permit (at no cost) from the MBTA. If approached by an MBTA official, a photographer must be willing to provide identification or show a permit. Except as otherwise permitted by law (e.g. lawful arrest), officials cannot confiscate or delete images without first receiving permission from the photographer. Persons taking images of MBTA property or vehicles from a public area not MBTA property (e.g. street or public sidewalk) are not subject to this policy.