This is the same train as in the previous shot. Two DPU's (Distributed Power Unit) bring up the tail-end as the train heads east on the Crookton Cutoff. With distributed power an engineer on the head-end of a train can remotely control, by radio signals, any locomotives attached to the tail-end of a train. There are two modes to this control. The remotes can simply mimic the throttle settings of the lead engines or their throttle settings can be set independently of the head-end units. An engineer may switch between these two control methods as is dictated by the terrain over which the train passes. DP makes longer and heavier trains possible with fewer locomotives.