Springfield-Boston was an "A-Day" acquisition in 1971 that continued the pre-Amtrak rights of Penn Central passenger trains to run on the Inland Route (though there was a brief interruption in actual service shortly before '71). Per Amtrak's birth charter, those trackage rights and passenger equipment were conveyed free in exchange for Penn Central being relieved of the burden of running those trains. The
Lake Shore Ltd. Boston section was not an A-Day route, being first instituted in 1975. The
LSL Boston trackage rights were finagled in the federal legislation that created Conrail from Penn Central's ashes: Amtrak got the route under
de facto A-Day rights in exchange for Conrail (feds) rebuilding the B&A corridor for freight, and Amtrak taking on ownership and rebuild of the B&A Post Road Branch (Schodack, NY to Rensselaer). The mainline rebuild took place during the very early 1980's. That's when the second track went away under the change from uni-directional to bi-directional signaling.
Amtrak didn't get any ownership or dispatching authority in its birth legislation, which has arguably been the whole network's Achilles heel. They only control the interlockings right at Springfield Union Station, which they got in the 1976 purchase agreement for the NEC and Springfield Lines from Conrail. But the B&A passenger schedules have been at the mercy of punitive freight prioritization for 50 years now, though moreso during the bad-neighbor Conrail era than with CSX (especially since the T took over Worcester-Framingham dispatch in 2009). Inland schedules, which were never all that flush to begin with, shed business because they were so oft-delayed...leading to the long draw-down and eventual cancellation of the route in 2004. The
Vermonter, when it ran on the B&A from 1995-2014, was similarly notorious for how oft-delayed it was by switching traffic at Palmer Yard. All allowances for future passenger traffic increases date to the quid pro quos that MassDOT secured from CSX 2 years ago to earn the state's blessing for the Pan Am merger. The
current grant application for jump-starting a couple Inland slots with speed improvements and new passing sidings follows that new framework, and the two parties have a M.O.U. on who pays what for anything that scales up-to and including the East-West and NNEIRI study recs.