The Evolution Series is a line of diesel locomotives built by GE Transportation Systems, initially designed to meet the U.S. EPA’s Tier 2 locomotive emissions standards that took effect in 2005. The first pre-production units were built in 2003. Evolution Series locomotives are equipped with either AC or DC traction motors, depending on the customer’s preference. All are powered by the GE GEVO engine.
The Evolution Series was named as one of the “10 Locomotives That Changed Railroading” by industry publication Trains Magazine. It was the only locomotive introduced after 1972 to be included in that list
Currently, six different Evolution Series models have been produced for the North American market. They are all six axle locomotives and have the wheel arrangement C-C (AAR classification) or Co’Co’ (UIC classification), except for the ES44C4 which has an A1A-A1A wheel arrangement. All North American Evolution Series locomotives are equipped from the factory with a Nathan-Airchime K5HL-R2 “Evolution” airhorn, and most later models are equipped with a Graham-White 373 (electronic) E-BELL.
The ES40DC (Evolution Series, 4000 HP, DC traction) replaced the Dash 9-40CW model in GE’s range and, like the former model, was delivered exclusively to Norfolk Southern Railway. ES44DC’s owned by CSX Transportation were also given this designation after being de-rated to 4,000 hp (3,000 kW). As of 2014, all of Norfolk Southern’s ES40DCs have been uprated to 4,400 horsepower (3,300 kW), making them ES44DCs.