Locomotives commonly used on the "Heartland Flyer" include the General Electric P42DC and P32-8WH. It used a combination of "Hi-Level" and "Superliner" railcars before converting to all "Superliners". For many years, the train was powered by only one locomotive, and a Non-Powered Control Unit (NPCU) on the end of the train opposite the locomotive made the train bi-directional. In 2009, the NPCU was replaced with a standard Genesis P42DC, giving the train locomotive power on both ends. The train returned to having an NPCU in 2015 before an accident in 2017 caused it to alternate between having power on both ends and having the NPCU.