The GN's electrification (it was in their Cascade mountains crossing), which was 11kV 25Hz AC from 1928-1956, was installed due to safety concerns inherent with running trains through long tunnels, mainly relating to what to do about the exhaust from locomotives. Remember that GN opened a very long tunnel there in early 1929. In 1956, the electrification was scrapped in favor of installing ventilation equipment in the tunnel. Several of GN's electric locomotives were then sold to the PRR and with only minor upgrades, were placed into heavy freight service on their lines.
BTW, before 1928, the GN had a much shorter electification using an interesting 3 phase system, using two overhead 'trolley' wires and the rails as conductors on an older line that that 1929 tunnel replaced. The 3 phase system only operated through the previous shorter tunnel and into small yards at either end of that tunnel and was used because the two wires being spaced farther apart allowed a safe place for brakemen to walk on top of the cars.
One interesting advantage for electric operation in mountainous regions was that the kinetic energy built up by a train ascending the hill could then be reused by the railroad through regenerative braking, using the locomotives' traction motors as generators to feed that built up energy back into the wire as that train descends the other side of the hill, controlling the train's speed on its descent and helping to lift the next train up the hill. If there was no ascending train ready, the railroad was also able to store that energy by pumping water into a reservour to be used later.
Also, the Milwaukee Road's much more extensive electrifications out west used an amazing (in that it worked) 6kV DC system.
___________________________________________ ____ _______________ Regards, | |\\ ____ | | | | |\\ Michael G. Koerner May they | | | | | | rise again! Appleton, Wisconsin USA | | | | | | ___________________________________________ | | | | | | _______________