Until operating rules were revised in the mid-1980's, the glassed-in number boards on the front of diesel locomotives allowed their owners the option of displaying the train number, rather than the engine number, when operating under a timetable and train order system. These boards were changed to display train numbers, including multiple sections, by the use of a letter-card system. Steam locos also had number boards, but with the cards exposed to the weather with the exception of Espee's cab-forwards. In practice, only Union Pacific and Southern Pacific made extensive use of the train-number option.
Last edited by 2nd trick op on Thu Mar 19, 2009 4:27 pm, edited 1 time in total.
What a revoltin' development this is! (William Bendix)