GE ES44AC

The ES44AC (Evolution Series, 4400 HP, AC traction) replaces the AC4400CW model in GE's range. These locomotives have been ordered by every Class I railroad in North America: Union Pacific Railroad (who refers to these locomotives as theC45ACCTE), BNSF Railway, CSX Transportation, Norfolk Southern Railway, Kansas City Southern Railway, Kansas City Southern de Mexico, Ferromex, Canadian Pacific Railway, and Canadian National Railway. Iowa Interstate Railroad ordered 14 ES44AC's in April 2008 to be delivered by October 2008 to handle an expected traffic growth of 25%-30%, resulting from new ethanol plants coming on line.^{[citation needed]} Iowa Interstate ordered two additional ES44AC's to be delivered in December 2009. Iowa Interstate again ordered 3 additional GE ES44AC's after selling 2 of the railroads EMD SD38-2's for the new ethanol plants.

CSX began receiving an order of 200 ES44AC's (referred to by CSX as the ES44AH) in December 2007. The "H" in ES44AHstands for "high", which is in reference to a combination of subsystems that produce high levels of tractive effort at low speeds. In order to be classified as an "AH" by CSX, a locomotive has to have not only an increased nominal weight (currently to 432,000 pounds or 196,000 kilograms), but also (1) steerable trucks, (2) TM3 adhesion control software, (3) software that extends to 33,000 pounds (15,000 kg) from 30,000 pounds (14,000 kg) the maximum amount of tractive effort that each traction motor is permitted to produce, and (4) GE's Rail Cleaner, which directs high-pressure air onto the rails in front of the sand nozzles forward of axle number one.

In September 2008, Norfolk Southern purchased 24 ES44AC's numbered 8000-8023, and began receiving the first of these units in October 2008. Ordered to be used on long haul coal trains, they were the first new AC locomotives ever purchased by NS.^{[citation needed]} An additional 65 units were ordered in 2011, numbered 8025-8090. 24 more units, numbered 8091-8115, were ordered at the beginning of 2012. 10 of these units: 8025, 8098-8105 & 8114 were painted in predecessor company "heritage" paint schemes for NS's 30th anniversary. All NS ES44AC's are built to CSX specifications, with the exception of the Hi-Ad trucks & headlight placement.

NS 30th Anniversary, #8100 in Nickel Plate livery

KCS's units are all painted in a Southern Belle paint scheme.^{[citation needed]}

Cemex took delivery of one ES44AC - built to CSXT specifications - numbered 81, in March 2008.

Canadian National's first order of ES44AC's was in January 2012, and as of 2015 they roster about 150 units, numbered in the 2800-2900 series.

Citirail/CREX acquired 100 ES44AC's for lease service. They are painted silver with blue & yellow nose striping and blue numbers. Most, if not all of these units, are leased to BNSF Railway.

In 2013, General Electric built one ES44AC, GECX 3000, as a test bed for their NextFuel natural gas power kit. The engine runs on liquefied natural gas from a fuel tender. The unit is currently part of BNSF's GE LNG test set, partnered with BNSF ES44AC no. 5815.