440 on the Pole Line - How Long, and Where?

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Somewhere I have an article from the 1913 (I think) volume of Railway Signal Engineer detailing the N&W's new installation of upper quadrant AC semaphore signals for automatic block signaling on the Bristol Line, with AC track circuits. 



The article mentions that, to power the new signal system, the N&W was hanging a 440 volt AC line on its poles, which line was to be fed by railroad-owned power houses spaced an intervals along the right-of-way.  One great advantage of the innovation was... get this... that stations along the way could now  be illuminated by that great invention, the electric light !  This makes perfect sense, as in 1913, there was very little electrification outside of cities and "commercial power" wasn't available in the countryside. 



I am told that "440 on the pole line" lasted on the Bristol Line until 1996-1997, when the pole line was eliminated and the railroad began "dropping commercial power" into each signal and crossing location.  However, at that time  440 was no longer  being drawn from railroad-owned generating stations, but was fed at a few locations by public utilities (probably at the locations where the old power houses had once been located.) 



This raises the interesting question of the railroad-owned power houses.  When did they go away?  And just where were they?  (My preliminary theory is that the power houses probably went away at the time the N&W installed DC coded track circuits and  CTC [ Centralized Traffic Control] in the 1940s, as by that time "rural electrification" had brought power lines to every town along  the railroad's main routes .) 



Anyone know the answers...? 



AC transmission is notorious for its poor propa gation (viz. "line loss" or "voltage drop,")  and some railroads which used AC propulsion located substations every ten miles.  I don't think the N&W would have located generating stations that close together, but certainly 50 miles would have been stretching it in 1913. 



-- abram burnett 


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