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Steam Locomotion in the 21st Century

The Recent History of Steam Locomotive Development

Diesel-electric vs. Steam Locomotives

Updated 13 February 2022

Diesel Advantages over Traditional Steam

(1) "Multiple-unit" capability, allowing several diesel locomotives to be connected together and controlled by a single operator.
(2) Very high starting tractive effort relative to weight.
(3) Use of light oil fuel which provided much cleaner operation.
(4) Use of mass-produced, standardized repair parts simplifying maintenance and repair procedures.
(5) Extensive "factory support" in the form of extensive operating and maintenance manuals, training, factory technicians to assist with repairs, etc.
(6) Significantly higher thermal efficiency (~25% at the rail typical for diesel-electric; 7% at the rail typical for "modern" steam- figures circa 1950).
(7) Higher availability (less time spent on routine repairs and maintenance).
(8) Individual powered trucks, each with a short wheelbase, capable of negotiating tighter curves and rough track.
(9) Less skill required to operate, especially at optimum efficiency.
(10) Better comfort for crew.

 

Traditional Steam Advantages over Diesel-Electric

(1) High horsepower-to-weight ratio.
(2) Very high horsepower achievable in a single locomotive.
(3) Much lower first cost per horsepower.
(4) Relatively simple to repair.
(5) Most spare parts can be fabricated locally from raw materials.
(6) Use of cheap, unrefined fuel (coal, wood, or heavy oil).

 

 

One of the best comparisons of steam vs. diesel-electric locomotives in the US was "A Practical Evaluation of Railroad Motive Power" by P.W. Kiefer, published in 1948. This compared the performance and economics of the New York Central's Niagara 4-8-4's vs. 2-unit EMD diesels in passenger service. This study determined that in this service the operating costs were very close, very slightly in favor of the diesels. However it has been noted that a 2-unit EMD consist could not equal the performance of one Niagara, and if a 3-unit EMD consist were used to equal the Niagara performance capability, the economics came out significantly in favor of steam. Nevertheless, the New York Central's subsequent motive power purchases were diesel.




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