Trains' fuel efficiency
Trains' fuel efficiency refers to the ability of rail systems to minimize fuel consumption while transporting passengers or freight. Historically, trains have evolved from horse-drawn carriages on wooden or stone tracks to modern systems that utilize advanced technologies, such as electric propulsion and magnetic levitation. The efficiency of freight and passenger trains has significantly improved since the early 1990s, with studies indicating a 20% increase in fuel efficiency in the U.S. rail industry during that period. Key factors contributing to this improvement include advancements in locomotive technology, optimized operational practices, and a shift towards more efficient traffic mixes, particularly with coal and intermodal shipments.
Different types of trains, including freight and passenger variants, have specific designs that impact their fuel efficiency. Innovations such as better locomotive designs, higher-capacity freight cars, and the adoption of renewable fuels, including biodiesel and battery-electric options, are shaping the future of rail transport. Additionally, increasing reliance on systemwide developments, like centralized train control, is expected to enhance overall operational efficiency. As the demand for sustainable transport grows, trains are seen as a viable solution to reduce environmental impacts compared to road and air travel.
Trains' fuel efficiency
Summary: The history of transportation through trains dates back nearly 500 years and includes systems with man- or horsepower and rails of stone or wood. Railways provide economic, social, and environmental benefits. There are different types of trains, with various levels of fuel efficiency.
A train is a connected series of vehicles that move along a track to transport passengers or cargo from place to place. The track usually consists of two rails, but certain trains are designed to run on monorails or maglev (magnetic levitation) guideways. Propulsion for the train is supplied by a separate locomotive or by motors in self-propelled multiple units. Many modern trains are powered by additional rails or by electricity supplied by overhead wires, although historically (from the early nineteenth century to the mid-twentieth century), the steam locomotive was the predominant form of locomotive power.
History of Trains and Rail Transport
The history of transportation through trains dates back nearly 500 years and includes systems that used manpower or horsepower and rails of stone or wood. Linked cars or carriers were later hauled by horses, pulled by a cable, or ran downhill by gravity (and some of these are still used today). However, the history of trains in the modern sense of linked cars powered by engines dates back to early nineteenth-century England, where the first rail transport systems appeared in the 1820s. These systems, which made use of the steam locomotive, were the first practical forms of mechanized land transport, and they remained the primary form of mechanized land transport for several decades.
Modern rail transport includes all land passenger and freight transport, which runs on both dual and single fixed rails. This mode of transport principally involves light rail, heavy rail, and trams yet can also include funicular and monorail modes. Railways provide economic, social, and environmental benefits. The last of these benefits is particularly relevant, with the current policy emphasis on the provision of sustainable transport services. Compared to road and air transport, rail travel is superior in relieving road traffic and reducing the number of road accidents. With a growth in air transport, rail also provides congestion-free surface entrée to airports.
Types of Trains
Different trains are designed for particular purposes. A train usually consists of a combination of one or more locomotives and attached railroad cars or a self-propelled multiple unit (mostly a single or articulated powered coach, called a railcar). Trains are made to run on a variety of railways, including atmospheric railways, maglev guideways, high-speed railways, rubber-tired underground railways, and cog and funicular railways.
A passenger train constitutes one or several coaches and locomotives. A train may also consist totally of passenger-carrying coaches, some or all of which are powered as a “multiple unit.” In many parts of our world, especially Europe and east Asia, high-speed rail is fundamental to mass transport of passengers.
Freight trains consist of trucks or wagons rather than carriages, although some parcel and mail trains (particularly traveling post offices) are outwardly more like passenger trains in appearance.
Mixed trains include cars for both freight and passenger accommodation. Such mixed trains are most likely to be used in areas where service is infrequent or where tracks are limited, and thus where running separate freight and passenger lines is not cost-effective (although the diverse needs of freight and passengers usually means that this approach is avoided where possible).
Special trains are trains that are also used for track maintenance; in some places, these systems are termed maintenance-of-way systems.
Fuel Efficiency
Studies indicate that in the period 1990–2006, rail fuel efficiency increased by about 20 percent, or an average of 1.1 percent per year. These figures represent the general industry average for the United States. Class I railroads (large-revenue carriers in the United States and Canada) have seen changes in railroad traffic mix, technologies, and operating practices. Many of these types of improvements took place without the strong incentive of rising diesel fuel prices after the year 2004.
The major factors behind improvements in rail fuel efficiency include changes in traffic mix, especially the growth of unit-train traffic and, in particular, coal and intermodal traffic; technological improvements in freight cars, locomotives, signals, train controls, dispatching systems, and track systems; and changes in operating practices that have lowered fuel consumption, such as the optimization of train meets and passes at sidings, training of staff and crew in fuel-saving operating techniques, and better scheduling to avoid delays. Gains in fuel efficiency over the period from 1990 to 2006 can be attributed to gains due to changes in railroad technology and operations, combined with factors varying by traffic type.
Rail and Railroad Technology Development
In considering new railroad operating methods and technologies, it should be noted that operational developments and railroad technology fall into three groups, which face very different barriers to successful application. The principal groups are single-unit developments, complete train or line-segment developments, and systemwide developments.
Single-unit developments constitute most locomotive and freight-car developments, such as better locomotives in terms of fuel efficiency, higher-capacity freight cars, and freight cars with reduced rolling resistance. Each such unit that is put into service provides an instant benefit. The benefits are usually simple to estimate and can be confirmed with short operating tests. Thus, railroads find it relatively easy to rationalize such investments.
The best exemplar of a complete train development is the unit train that carries train-load quantities of freight from origin to destination with no intermediate switching. Unit trains also serve as platforms for other technologies and operating methods, such as electrically controlled pneumatic (ECP) brakes, which have to be fitted throughout the train to be effective, or distributed and remotely controlled locomotive power. Line-segment developments include upgraded signal systems, such as centralized train control (CTC). Many of the large systems still have territories without CTC systems.
Systemwide developments are developments whose benefits are realized only when applied to a significant fraction of a railroad network or to a whole network. Examples are positive train control (PTC), which needs equipment both at trackside and on locomotives and will yield safety and operational benefits only if all trains and routes in an area are PTC-equipped. Another example would be ECP brakes on freight cars used in mixed freight (not in unit trains).
Railroad companies have also increased use of renewable diesel and biodiesel blends. These fuels, which are made from renewable energy sources, can be blended with petroleum diesel fuel to reduce carbon emissions by 20 percent. Railroads are also testing battery-electric locomotives and researching hydrogen fuel cells to power locomotives for long-haul shipments.
Bibliography
Federal Railroad Administration. “Comparative Evaluation of Rail and Truck Fuel Efficiency on Competitive Corridors.” November 19, 2009. www.fra.dot.gov/Downloads/Comparative‗Evaluation‗Rail‗Truck‗Fuel‗Efficiency.pdf.
"How Are Locomotives Getting More Fuel Efficient for the Railroad Industry?" Union Pacific, 5 Apr. 2022, www.up.com/customers/track-record/tr040522-locomotive-fuel-efficiency-improvements.htm. Accessed 6 Aug. 2024.
Jong, Jyh-cherng, and En-fu Chang. “Models for Estimating Energy Consumption of Electric Trains.” Journal of the Eastern Asia Society for Transportation Studies 6 (2005).
Lewis, R., and U. Olofsson. Wheel/Rail Interface Handbook. Boca Raton, FL: CRC Press, 2009.
"Moving Miles Ahead on Sustainability." Association of American Railroads, www.aar.org/article/freight-rail-moving-miles-ahead-on-sustainability/. Accessed 6 Aug. 2024.
Voestalpine.com. “Technology and Expertise.” www.voestalpine.com/schienen/en/technology‗and‗competence.html.