What's Old is New Again

Posted by George Hamlin
on Saturday, January 15, 2022

Freight trains with multiple locomotives other than on the head end are hardly new.  Helper engines (with separate crews operating them) pushing on the rear of the train are certainly not a new concept.  Sometimes they were cut into the body of the train, instead; this was sometimes referred to as a “swing” helper, since they both pushed and pulled.  A notable utilization of this concept was on the Southern Pacific’s movement of crude oil unit trains from Bakersfield, California to a refinery in the Los Angeles basin, over the Techachapi mountains, including the famous loop west of the town of the same name.

At one point in the 1960s, the Norfolk & Western Railway operated a loaded coal train with 500 loaded hoppers, and two sets of locomotives, one buried in the consist.  This monstrosity was over 20,000 feet long, and the demonstration run didn’t produce any offspring; I’ve read accounts that it required as long as 30 minutes to pass, which probably didn’t impress those waiting for its passage favorably.

The N&W’s future partner, the Southern Railway, however, made use of remotely-controlled crewless locomotives beginning the in the 1960s, by equipping some of its diesel locomotives to act as “master”, or controlling, units (operated by the normal crew), which transmitted instructions by radio to the following “slave” units via what was termed a “radio car”, or RC, for short, which was coupled to the mid-train power and “commanded” them to operate as needed via multiple-unit connections.  Some of the RCs were created using old locomotive frames; the feedstock for this included an EMD FT B-unit; Alco road switchers and Fairbanks-Morse switchers.

This proved to be relatively successful, and continued following the Norfolk Southern merger, as shown in the picture above of an eastbound freight coming north out of Atlanta at Duluth, Georgia, on May 14, 1983.  The remote units were SD40 3195 and SD40-2 3224; they were under the tutelage of RC 905938.  A pair of SD40-2s, 3311 and 3208, were the head-end power on this train, for a total of 12,000 horsepower, nicely distributed in the train’s consist.

While they wouldn’t last much longer, at the rear of the train was a caboose, the X333, in the traditional red color.


Today’s DPUs (distributed power units) no longer require a separate car to relay the commands coming from the lead unit to the remotes, via miniaturization of the electronics.  In addition, the locomotives have advanced considerably beyond 3,000 horsepower to figures in the mid-4000s, about 1.5 times that of the locomotives pictured here.

With the relatively recent advent of PSR (“precision scheduled railroading”), large-scale remotely-controlled locomotion on U.S. railroads has had a resurgence and also has greatly expanded both in its overall usage and the lengths of the trains of the trains that make use of DPUs; I’ve seen 12,000 foot intermodals in my neighborhood recently.

Unfortunately for traditionalists, however, the red caboose has gone the way of the radio cars…

(Photos by George Hamlin)

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