Resources to preserve old RR infrastructure in Massachusetts
In the 1970s the State in Massachusetts commanded all cities and towns in the state to set up Historical Commissions. Many already had Historical "Societies", but those are not a part of a municipal government. The Secretary of State's office oversees the Mass Historic Commission and they developed a series of templates for writing historic narratives about specific properties. The cities and town were then directed to use them and develop a publicly accessible database of all the historic properties in every community in the Commonwealth.
Now since this piece is about historic resources for preserving RR infrastructure, lets look at the town of Billerica where the old B&M RR had a huge presence that community. Something like 600 acres with a huge yard, maintenance facilities, offices etc. It was all there --and largely still is. Though the B&M RR as an operating RR is no longer extant. The current name of the operating entity entity is Pan Am Railways, because the B&M sold off huge swaths of all their assets to the state of Mass. (managed by the MBTA actually) That include much of the built environment at Iron Horse Park.
In the case of Billerica, they have quite a few historic resources in town. Over 450 places on the list. Over 30 alone are related to the B&M RR's facilities in Iron Horse Park. Below is a screenshot of one of the pages detailing the railroad infrastructure. At the very bottom is one of the write-ups. Done by a consultant for the MBTA. I should mention too that the Form Bs are not encompassing, but are only a couple or three pages. They wet the appetite so to speak.