BOOK REVIEW: Diesel-Electric Locomotives – How They Work, Use Energy, and Can Become More Efficient and Environmentally Sustainable

Written by David C. Lester, Managing Editor, Railway Track & Structures
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While the documentation of diesel locomotives is extensive, Walter Simpson’s new book brings a fresh perspective to the literature. The book is an excellent primer on diesel locomotives that is well-illustrated with photographs and color-coded drawings of diesels and their parts. However, the underlying theme of the book is locomotive energy efficiency, fuel economy and the Environmental Protection Agency’s emissions standards, leading to Tier 4 compliance. There is also a chapter on the environmental sustainability of railroads.

The author has a deep interest in railroads, but his professional background is in energy management and environmental education; he served for 26 years as Energy Officer at the State University of New York at Buffalo (UB). He mentions in the Acknowledgements section that he was very grateful to rail industry experts who strengthened his precise technical understanding of locomotives and railroads. He notes, “Because locomotive manufacturers and railroads generally don’t talk about diesel-electric locomotive energy efficiency, investigating [this] topic was at times like peeling back an onion—or what one consultant called penetrating the code of silence.”

Chapter Three is devoted to locomotive fuel economy and energy efficiency. Simpson discusses some well-known efficiencies inherent in rail transportation, such as rolling resistance and aerodynamic advantages, when compared to other forms of transportation. He adds that poorly maintained track is energy inefficient because the rolling resistance is greater than on well-maintained track. Aerodynamic advantages, Simpson notes, are inherent in trains “because they are long and narrow and have a very small cross section per unit of cargo or per number of cars or passengers.”

Simpson goes on to discuss the differences between locomotive fuel use vs. locomotive fuel economy. As most readers know, the most prevalent measure publicized by the industry is the amount of tonnage that can be moved a certain distance with a given amount of fuel—usually one gallon. Actual fuel usage, on the other hand, depends on a number of variables, “such as total annual hauling, train load management (i.e., the amount of freight or passengers per car and per train), rail system traffic management, fuel consumed in yard activities and whether the railroad runs largely on flat territory (e.g., CN) or predominantly mountainous territory (e.g., Canadian Pacific).” Simpson provides additional examples of variables affecting locomotive fuel use—locomotive age, model and design efficiency; fuel type; train length and weight; congestion; two-way hauls; track work en route; maintenance; wheel/rail interface management; and weather and season. Each of these areas is the subject of significant engineering research and testing, and the author discusses many of these issues in greater detail in subsequent chapters. There is an especially valuable discussion of the EPA Tier 4 emissions standards program in Chapter Five.

While this book can certainly stand alone as an introduction to diesel-electric locomotives, prior knowledge of at least the basics of motive power proves helpful to understanding the workings of locomotives, and the myriad ways that fuel economy and fuel use can be improved. Concern about global warming and decreasing humankind’s carbon footprint are key themes in the last two chapters of the book, which explore future directions for diesel-electric locomotives, along with railroad efforts to improve sustainability and contribute to a cleaner, healthier environment.

The chapters are followed by sections on acronyms and abbreviations, sources and recommended reading, useful notes, and an index. Also, there is a helpful website devoted to the book found at This book is highly recommended to anyone interested in diesel-electric operation and maximizing the environmental benefits of rail transportation.

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Categories: Class I, Freight, Locomotives, Mechanical, Regulatory, Short Lines & Regionals, Switching & Terminal Tags: