Canadian National CN 2865 GE ES44AC DPU power to an empty CN coal train is northbound as it passes a loaded BNSF grain train under the old Illinois Central coaling tower in Reevesville, Illinois on January 2, 2021.
Distributed power (DP) (unit U) is a generic term referring to the physical distribution—at intermediate points throughout the length of a train—of separate motive power groups. Such ‘groups’ may be single units or multiple consists and are remotely controlled from the leading locomotive. The practice allows locomotives to be placed anywhere within the length of a train when standard multiple-unit (MU) operation is impossible or impractical. DP can be achieved by wireless (RF connectivity) or wired (trainlined) means. Wired systems now provided by various suppliers use the cabling already extant throughout an ECP train.