Steam-powered locomotives are grandly impressive, amazing powerful, and a high point in the Industrial Revolution's "Age of Steam". But the cold Montana winters can suck so much heat out of their boilers that they can barely make steam, and even in the best of conditions steam locomotives are very high-maintenance. The Butte, Anaconda, & Pacific Railway, a subsidiary of the Anaconda Copper Mining Company, and right on the Milwaukee's doorstep, was already converting to electrically powered locomotives, and it was proving to be an outstanding success. The president of the mining company was a Milwaukee director, and the Milwaukee was very interested. In 1914 they began electrifying the Rocky Mountain division in Montana, using a 3,000 volt DC system that was considered the most advanced railway electric system of its time.
The essential aspect of an electrified railway is not in the use of electrically driven motors (most of today's "diesel" locomotives are actually "diesel-electric", using a combination of diesel engines, generators, and electrical motors), but in using electricity generated from a stationary generating plant. The key drawback of such a system is the need for a distribution system to get the electricity to the locomotive. This is usually done with a special wire (a catenary) hung over all the track where the electric locomotive is to operate. This wire, all of its supports, and the distribution system to feed it, is a large capital expense.
But electrification has substantial advantages. First and foremost, electric motors are largely unaffected by cold weather. At peak demand they perform better than steam engines, or even diesel engines, and can even be run over their rated capacity for short periods. Electric locomotives can be run longer between servicing, and require much less servicing. (And it turned out that they lasted much longer.) And it is much cheaper to produce power from a stationary generating plant, especially if it is hydro-electric. Another compelling factor for the Milwaukee was that steam locomotives big enough to pull trains of the size expected at the speeds desired would have some trouble negotiating the steeper grades and tighter curves in the mountainous sections. Electric locomotives were more powerful, more reliable, and much easier and cheaper to operate and maintain.
Perhaps the coolest aspect of the electrification system adopted by the Milwaukee was regeneration. When trains went down hill the electric motors were used as generators. This both slowed the train down (with substantial savings in the cost of replacing brake-shoes), and returned power to the system to help ascending trains, reducing the overall power needs by about twelve percent. Heavy capital costs, but significant operational savings (despite padding of costs); the net benefit was later found to amount to a return on investment of nine percent annually.
The Rocky Mountain Division was electrified first, between Harlowton, Montana, and Avery, Idaho, across the Bitterroot Mountains; it came into service in 1917. Electrification of the Coast Division mainline between Tacoma and Othello (207 miles) was completed in 1919, though the last leg into Seattle was not done until 1926. Unfortunately, there was no money at the time to electrify "The Gap" between Othello and Avery, and the need to maintain non-electric traction there later diluted the use of electric traction on the rest of the Coast Division.
Electrification was undeniably a good thing, and a primary reason why the Milwaukee Road could move freight on its mainline at less cost than its competition. So it is quite curious why they decided (in 1970) to abandon electrification. There were claims that the electrical system was worn-out and obsolete, and that the electric locomotives were worn-out. Michael Sol, in his excellent monograph "The end of the Milwaukee electrification", says that overhead was "in very good condition", and that: "The remaining locomotives were not worn out, or even close to the end of their economic life." He says that: "The only component of that system that was in actual engineering failure was the track." This was due to a decade of "deferring" needed maintenance. And was in no way alleviated by de-electrifying.
The electrical system probably did need an upgrade. (Many pictures show two big "Big Joe" electric locomotives with a diesel locomotive: some feeder stations did not have enough capacity to supply three Big Joes simultaneously at peak load.) But it has been claimed that the entire system, including locomotives, could have been upgraded for less cost than "dieselization".
The Milwaukee's management claimed that "dieselization" (converting to the use of diesel locomotives) was more economic. While this was certainly true in regards of steam locomotives, which were very expensive to operate, it is rather doubtful in regards of electric locomotives. Diesel locomotives simply did not perform as well as electric, failed more often, and in the end (1974) cost twice as much to operate. The pertinent economic factors would seem to be deeper, such as matters of amortization and tax write-offs, or other interests of the banks that controlled the Milwaukee. Or perhaps the Board of Directors just wasn't paying attention.
One factor in the decision to scrap electrification may have been the price of copper. At one point the price soared, and it was estimated that the Milwaukee's overhead wire was worth $10 million as scrap. Caught between the Scylla and Charybdis of little revenue and massive expensives, an option with such a windfall must have been dazzling. But in the end the price dropped, and they got only $5 million. This was a pittance against the (at a minimum) $39 million it cost to replace it with diesel power.
Electric operation on the Coast division (between Seattle and Othello) was terminated in 1971. The remaining electric operation (on the Rocky Mountain division) was terminated in June, 1974. De-electrification was not enough to avert bankruptcy three years later, and probably contributed to it.
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