trains during the engine change, and detached from northbound trains; this eliminated the need for passengers to change trains. The Connecticut Valley Service name was soon dropped, and shuttle trains were named in timetables as sections of their connecting trains. The elimination of the second track on the line beginning in 1990 sharply reduced capacity, limiting frequencies to four daily shuttle round trips plus several through trips. On October 28, 1995, most Northeast Corridor service including the shuttle trains were consolidated under the NortheastDirect brand. Electrification was extended to Boston in 2000, and engine changes were eliminated over the next two years. The cumbersome split/merge procedure was abandoned in favor of dedicated shuttle trains with cross-platform connections to through trains. The shuttle trains began to use Former Metroliner cab cars, which had become available when replaced by new equipment on West Coast routes. This allowed them to operate in push–pull format, eliminating the need to wye or loop the trainsets at New Haven and Springfield. The NortheastDirect name was dropped in September 2001; Northeast Corridor trains became the Acela Regional (later Regional then Northeast Regional), while the shuttle trains became unnamed. They remained unnamed until 2019 when they received the Hartford Line and Valley Flyer names. Mail service Until Amtrak discontinued all mail-hauling operations in 2005, the postal distribution center in Springfield, MA was a significant customer. Up until about the year 2000, Springfield was served by a dedicated mail train which would run overnight up the Inland Route to Springfield. After this train was canceled, mail cars were instead added to the early morning Train 190, to make pickups at large cities along the Northeast Corridor. At New Haven these mail cars would be removed from the rear of Train 190 and added to Shuttle Train 490, sometimes sandwiching the locomotive in the middle of the train. Hartford Line expansion Until August 2015, daily service in each direction on the Springfield Line consisted of four Shuttles, the Vermonter, and one or two Northeast Regional trains. Between August 3, 2015 and December 31, 2017, several round trips on weekdays were replaced by buses to accommodate double track construction for the ConnDOT Hartford Line commuter rail service. On June 9, 2018, three additional weekday Shuttle round trips were added as part of the startup of Hartford Line service. This change also added connections with some Amtrak Acela Express service in New