Unlike the TGV, the Acela sets employ active tilting technology, which helps control lateral centrifugal force, allowing the train to travel at higher speeds on the sharply curved NEC without disturbing passengers.

The present Acela Express equipment is scheduled to be replaced by new Avelia Liberty (similar to SNCF TGV M) sets beginning in spring 2025,[3] though a firm start date has not yet been announced.

The new trains will have greater passenger capacity and an enhanced active tilt system that will allow faster speed on the many curved sections of the route.

An X 2000 train was leased from Sweden for test runs from October 1992 to January 1993, followed by revenue service between Washington DC and New York City from February to May and August to September 1993.

[5] Requirements for the trainset included the ability to reach 150 miles per hour (240 km/h) and withstand a collision with a freight train at speed without collapsing.

[12] By 2004, Amtrak had settled contract disputes with the consortium, paying a total of $1.2 billion for the 20 sets, plus 15 extra electric locomotives, and the construction of maintenance facilities in Boston, New York, and Washington.

[21] In May 2018, Amtrak announced a 14-month program to refresh the interiors of the Acela sets, including new seat cushions and covers, new aisle carpeting, and a deep clean.

[22] In January 2014, Amtrak issued a request for proposals on 28 or more new model Acela sets, in a combined order with the California High-Speed Rail Authority.

[23] After discussions with manufacturers, Amtrak and the California High Speed Rail Authority concluded their needs were too disparate for common rolling stock and decided not to pursue the joint option.

[24] The present Acela Express equipment is scheduled to be replaced by new Avelia Liberty (similar to SNCF TGV M) it is currently unknown when the trains will come into service.

[25] The new trains will have greater passenger capacity and an enhanced active tilt system that will allow faster speed on the many curved sections of the route.

The sets use identical 6,200 horsepower (4,600 kW) power cars at each end which operate on a voltage of 11,000 volts AC, and either 25 or 60 Hz frequency, derives several components from the TGV,[26] such as the third-generation TGV's traction system (including the four asynchronous AC motors per power car, rectifiers, inverters, and regenerative braking), the trucks/bogies structure (a long wheelbase dual transom H frame welded steel with outboard mounted tapered roller bearings), the brake discs (although there are only three per axle, versus four on the TGV), and crash energy management techniques to control structural deformation in the event of an accident.

[26] The Tier II crash standards, adopted in 1999, have also resulted in the passenger cars being designed without steps and trapdoors, which means that the sets can only serve lines with high-level platforms such as the Northeast Corridor.

[36] To prepare for the Acela launch, Amtrak upgraded the track along the Connecticut shoreline east of New Haven to allow maximum speeds in excess of 110 mph (177 km/h).

$450 million was allotted by President Barack Obama's administration to replace catenary and upgrade signals[39] between Trenton and New Brunswick, which will allow speeds of 160 mph (257 km/h) over a 23 mi (37 km) stretch.

[40][needs update] This section of track holds the record for the highest speed by a train in the US, which is 170.8 mph (274.9 km/h), achieved in a test run by the U.S./Canada-built UAC TurboTrain on December 20, 1967.