When an automobile is recycled, nothing much remains but molten metal. When a modern diesel locomotive is recycled, however, the frame and much of the exterior is re-used, while internal organs are replaced or upgraded. In an era when a new freight locomotive can cost upwards of $2 million, recycling old power makes both economic and ecological sense.
These models showcase the locomotive recycling efforts of the Norfolk Southern railroad. ECO engine 4700, assigned to yard service in the Chicago area, is one of a group of engines rebuilt in 2015-2016 to deliver lower emissions in major urban areas. The program was partially funded by Federal and state environmental grants - hence the map of Illinois and the slogan "Working Together for a Cleaner State" on its sides.
Locomotives 4000 and 4002 are lead engines in the "DC to AC" program begun in 2015, to upgrade 20-year-old diesels with more horsepower, lower emissions, more comfortable cabs, and conversion to AC electric motors in their 6-axle trucks. Compared with the DC motors that were once standard on diesels, AC motors can start a heavier train with the same engine horsepower; in effect, they put more of the locomotive's horsepower on the rails.