The first of 70 Amtrak advanced technology electric locomotives being built by Siemens have begun rolling off the assembly line.

The first units of the $466 million order, to be used in the northeast, will be field tested this summer for entry into revenue service in the fall.

Using Siemens’ innovative and proven rail technology, the Amtrak Cities Sprinter locomotives are being assembled in Siemens’ Sacramento, Calif., rail manufacturing plant powered by renewable energy, with parts built from its plants in Norwood, Ohio; Alpharetta, Ga.; and Richland, Miss., and nearly 70 suppliers, representing more than 60 cities and 23 states.

The new locomotives will operate on Northeast Regional trains at speeds up to 125 mph on the Northeast Corridor (NEC) along the Washington — New York — Boston route and on Keystone Service trains at speeds up to 110 mph on the Keystone Corridor from Philadelphia to Harrisburg, Pa.

In addition, all long-distance trains operating on the NEC will be powered by the new locomotives.

The new locomotives are designed for easier maintenance, will improve energy efficiency by using a regenerative braking system that will feed energy back into the power grid and will enhance mobility for the people, businesses and economy of the entire Northeast region. They also meet the latest federal rail safety regulations.

The first three locomotives will undergo a comprehensive testing program this summer, including two at a U.S. Department of Transportation facility in Pueblo, Colo., and one on the NEC. Once they are commissioned, production of the remaining units will ramp up for monthly delivery through 2016.