Amtrak passengers along the Northeast Corridor and in Pennsylvania will start seeing new hardware up front, with brand new locomotives replacing ones that are between 25 and 35 years old.

The new Amtrak Cities Sprinter (ACS-64) electric locomotives are built by Siemens in the United States as part of a $466 million contract for new rail equipment awarded in 2010. The locomotives are capable of speeds up to 125 mph on Northeast Regional service between Boston and Washington, D.C. and can do 110 mph on the Keystone Corridor between Philadelphia and Harrisburg, Pa. Most importantly, those speeds aren't just for a spec sheet: The ACS-64 can do 125 while pulling up to 18 railcars.

In addition to power, the new 8,600-hp locomotives feature regenerative braking that can return up to 5 MW of electricity back into the grid through the catenary. According to Amtrak, the new trains are also more efficient and could save over $300 million in energy costs over the next two decades.

But wait, there's more. Safety has improved across the board, with a redesigned safety cage and an "anti-climber" – a structure that keeps keeps railcars from lifting off the tracks and hitting the top of the locomotive in an accident.

The ACS-64 is based on Siemens' EuroSprinter, of which more than 1,600 units are already in service. Reliability is also said to be improved when compared to Amtrak's existing fleet, with on-board diagnostics and numerous redundant systems. That's especially important on the Northeast Corridor, the most heavily traveled passenger rail route in the states.

"The new Amtrak locomotives will help power the economic future of the Northeast region, provide more reliable and efficient service for passengers, and support the rebirth of rail manufacturing in America," said Amtrak president Joseph Boardman.

The first ACS-64 will enter revenue service this fall after a period of testing, and 70 new locomotives will be put into service before 2016. They'll replace locomotives made by Electro-Motive diesel between 1978 and 1988. It's part of an overall fleet upgrade that aims to replace all of Amtrak's cars and power plants over the next 30 years.