Granddaddy of a line for northeast regional. Once completed a new world of Amtrak and commuter rail could be open all along the northeast and mid Atlantic. Just starting with Amtrak, you could then open other commuter lines in dlc. This cold also be used to TSW.
Never gonna happen, at least not as one continuous route. It would have to be done in sections. Also some of the commuter railroads like Septa and Marc are refusing to give DTG a license (or they're charging too much and DTG doesn't want to pay). Some people are working on Workshop routes, but unless these commuter railroads give DTG a license, the existing NEC routes are probably the only ones you're gonna get.