The layer includes active passenger, freight, and MBTA Commuter Rail and Rapid Transit railways, along with abandoned rail lines. In many instances there is more than one track per rail line, and rail yards and spurs are included.

The Central Transportation Planning Staff updated and enhanced railroad linework distributed by the United States Geological Survey (USGS) as 1:100,000 Digital Line Graphs (DLGs). The original 1:100,000 DLG data were conflated to the orthophoto-derived 1:5,000 Centerline linework now used in this layer. CTPS added several attributes pertaining to type of service, MBTA Commuter Rail status, rail line ownership, and freight and passenger operation.

The statewide layer is named TRAINS_ARC. Other rail data from CTPS are TRAINS_NODE (named station locations) and TRAINS_RTE_TRAIN (MBTA Commuter Rail Routes, a dissolved subset of this layer). In addition, the MBTA Rapid Transit data are stored in separate layers: MBTA_ARC (subway, trolley, Silver Line vehicles) and MBTA_NODE (T stops).

The data are up-to-date through July 15, 2014.