Acela Express trains are the fastest trainsets in the Americas; they attain 150 miles per hour (240 km/h) on 33.9 miles (54.6 km) of Amtrak's flagship service along the Northeast Corridor (NEC) in the Northeastern United States between Washington, D.C. and Boston via 14 intermediate stops, including Baltimore, Philadelphia, and New York City..
Acela operates along routes that are used by freight and slower regional passenger traffic, and only reaches the maximum allowed speed of the tracks along some sections, with the fastest peak speed along segments between Mansfield, Massachusetts and Richmond, Rhode Island. Acela trains use tilting technology, which helps control lateral centripetal forces, allowing the train to travel at higher speeds on the sharply curved NEC without disturbing passengers.
The fastest speed operation occurs mostly along the 226-mile (364 km) route from Pennsylvania Station in New York City to Union Station in Washington, D.C., with a fastest scheduled time of 2 hours and 45 minutes and an average speed of 82.2 mph (132 km/h), including time spent at intermediate stops.
The Acela's speed is limited by traffic and infrastructure on the route's northern half. On the 231-mile (372 km) section from Boston's South Station to New York's Penn Station, the fastest scheduled time is 3 hours and 30 minutes, or an average speed of 66 mph (106 km/h). Along this section, Acela has still captured a 54% share of the combined train and air market. The entire 457-mile (735 km) route from Boston to Washington takes between 6 hours, 38 minutes and 6 hours, 50 minutes, at an average of around 70.3 mph (113 km/h).
The present Acela Express equipment will be replaced by new Avelia Liberty trainsets beginning in 2021. Amtrak will retire all current trains by the end of 2022.