Amtrak's Acela Express train at Union Station, Washington, DC

Acela Express (often called simply Acela) is Amtrak's rail service that uses high-speed tilting trains. Acela operates along the Northeast Corridor (NEC)in the Northeast United States between Washington, D.C., and Boston via Baltimore, Philadelphia, and New York. The tilting design allows the train to travel at higher speeds on the sharply curved NEC without disturbing passengers, by lowering lateral centrifugal forces, based on the concept of banked turns.