UP ordered 47 DDA40X units, 6900-6946, which were delivered in time for the UP Centennial in 1969, hence the name Centennial for the units. Geared for high speed running, it was not uncommon for them to do 80+ mph, and they were primarily used on the UP's hottest intermodal and merchandise trains. They could be seen on any mainline on the system, but were perhaps more frequently seen on lines west of North Platte, Nebraska, where big distances allowed them to stretch their legs and move some serious freight in a hurry. Originally intended to be operated in trios, that practice ended when UP developed the "Fast Forty" SD40-2, also geared high to run with the Centennials. Thus, it became common for a pair of Centennials to bracket a Fast Forty, thus creating the SD40-2 Sandwich. In this photo, there are indeed two Centennials and also two Fast Forties, giving this train a rather high horsepower-to-ton ratio, possibly as much as six or even eight to one. This allowed for incredible acceleration, a prime consideration for the movement of premium traffic over the railroad. Back then, the UP was all about making a good impression with the public and sponsored a number of television commercials, which played during prime-time programming for a number of years. Here is a link to the original UP commercial, from their own website: http://www.up.com/aboutup/history/gbrr For those of us who remember seeing those commercials on TV way back when, it's a powerful reminder of how things on the UP used to be.
For those of us who remember seeing those commercials on TV way back when, it's a powerful reminder of how things on the UP used to be.