This polyline datalayer depicts MARTA rail routes with associated attribute data for the Atlanta Regional Commission's (ARC) 10-county region. ARC documentation states that: This Theme was created in ArcView through 'heads up' digitizing, using MARTA's digital road network as a basemap. For the purpose of this CD, ARC's GIS Division converted the original ArcView shapefile to ARC/INFO format for re-work in ArcEdit. Some of the arcs were adjusted to improve the positional accuracy against the 1993 Digital Orthophoto Quarter Quad (DOQQ) imagery and to coincide with other Themes, primarily MARTA bus routes and rail stations. ARC also used 1999 digital imagery for improved positional accuracy of the new expansion of the North Line to Sandy Springs and North Springs.