The red lights of F40 P-31 pierce the darkness at the Anchorage depot. P-31 is used at the rear of the weekly winter Aurora for a variety of reasons. Many snow slides occurred last year which resulted in reverse shoves for long distances. This year P 31 was added so the train crew can swap ends and head out the other way. P-31 also provides back up Head End Power (HEP) in case something goes wrong with the other two HEP units and can provide 800 KW. It’s also a light piece of equipment that doesn’t burn any fuel idling unless the GEN sets are running. Finally, it doesn’t bounce around back there as much.” February 2021