Recent railway industry campaigns have highlighted the relative average fuel efficiency of freight and passenger trains as a key benefit of the railway transportation mode. These efficiencies are anticipated to increase rail market share as rising energy costs make less efficient competing modes less attractive. However, the fuel consumption and energy efficiency of a specific passenger or freight rail system, and even individual trains, depend on many factors. Changes in these factors can have various effects on the overall fuel consumption and efficiency of the system. One of these factors is the amount of congestion and delay due to increased traffic on the line. Thus, it is possible that the additional traffic anticipated to shift to the rail mode due to its energy benefits may increase congestion and actually have a negative impact on overall network energy efficiency. Such a case would tend to dampen the future shift of traffic to the rail mode. While simple train performance calculators can evaluate the energy efficiency of a train for an ideal run, more powerful train dispatching simulation software is required to simulate the performance of trains in realistic operating scenarios on congested single-track lines. Using this software, the relative impact of congestion on efficiency can be analyzed and compared to changes in factors related to fuel consumption. In this study, several factors affecting the efficiency of both passenger and freight rail systems were selected for analysis. Rail Traffic Controller (RTC), a train dispatching software, simulated representative single-track rail subdivisions to determine the performance of specific passenger and freight trains under different combinations of factor level settings. For passenger rail, the effects of traffic volume and station spacing on fuel consumption were analyzed while the effects of traffic volume and average speed were analyzed for freight rail. Each system was analyzed on level track and on territory with grades. Preliminary results suggest that passenger trains, if given priority, maintain their efficiency until large numbers of passenger trains are present on the network, while freight trains experience degradation in energy efficiency as congestion increases. These results will be used to develop a factorial experiment to evaluate the relative sensitivity of freight and passenger rail efficiency to congestion and other system parameters. The paper concludes with a brief discussion of possible technologies to improve efficiency and offset potential losses due to future congestion.

After labor expenses, the cost of fuel is the largest operating budget expense item for freight and passenger rail operations in the United States. Because fuel is such a costly component of operations, the railroad industry is constantly researching and testing new methods either to reduce the volume of fuel consumed or to switch to less-expensive fuels and sources of energy. An understanding of the factors that affect fuel consumption and their interactions is valuable for analyzing the feasibility of a given technology. Such knowledge allows for more intelligent extrapolation of simulation and laboratory results across a range of routes and in-service operating conditions. This research investigates the relative effects of infrastructure, equipment, and operating parameters on fuel efficiency for freight and passenger railroads on a mixed-use corridor. Partial factorial experiments investigate the effects of multiple factors on freight and passenger train fuel efficiency. Rail simulation software is used to run trial cases of single-track lines with heterogeneous traffic and to calculate energy-efficiency metrics. Results from the simulations are used to create two multivariate regression models for freight and passenger rail fuel efficiency. A sensitivity analysis identifies the relative effects of these factors on freight and passenger train fuel efficiency. By understanding the relative influence of various parameters on fuel efficiency, practitioners can focus data collection, modeling, and other fuel-saving efforts on the most significant factors.

Because of growing concerns about the future environmental impact of passenger travel, modal energy efficiency is becoming increasingly important when benefits and costs of transportation system investment are evaluated. Because passenger rail systems are often cited as being relatively more energy efficient than other modes, reduced environmental impact is one justification for investment in new commuter rail projects. It is important that studies of purported environmental benefits analyze the energy efficiency of passenger rail systems and competing modes accurately and fairly by clearly defining the flow of energy through each transportation system. Furthermore, operational practices and constraints of the railway environment can complicate the analysis of energy efficiency; this complication makes it important to choose metrics that accurately describe the situation. This research identifies and describes four methods for analyzing the energy efficiency of passenger rail systems. Each method applies to a different system within the energy flow path. The combined methods are used to analyze the energy efficiency of 25 commuter rail systems in the United States. The results of each energy efficiency calculation method are then compared to illustrate how the relative attractiveness of each system can change on the basis of the selected analysis approach. By better understanding the challenges of conducting energy efficiency analyses involving different energy sources and fair comparison methods, researchers and policy makers can make informed decisions concerning the most appropriate method of analysis for drawing accurate comparisons between rail technologies and competing modes.

Commuter rail systems are widely regarded as an effective transportation alternative to reduce energy consumption and emissions in large urban areas. Use of commuter rail systems in the United States is on the rise, with annual ridership increasing by 28 percent between 1997 and 2007 [1]. With growing concerns about the sustainability and environmental impacts of transportation, modal energy efficiency is increasingly considered amongst the metrics to evaluate the benefits and costs of transportation systems and justify future investment. To gauge the relative long-term efficiency trends for rail as an urban transportation mode, this study analyzes historic trends in energy efficiency metrics for US commuter rail systems. Commuter rail systems receiving, or benefiting from, Federal Transit Administration (FTA) grants are required to report operations and energy consumption data on an annual basis to the National Transit Database (NTD). NTD data on energy consumption, operations, and services supplied from 1997 to 2011 are analyzed to determine historic trends in various energy efficiency metrics for the commuter rail mode as a whole. The data analysis and comparison of the results with the highway mode is complicated by the use of electric traction by some commuter rail operators. These operators report energy consumption in purchased electricity (kWh) instead of gallons of liquid fuel. The different approaches that can be employed to compare these two forms of propulsion and their intrinsic efficiencies and energy sources are discussed. Energy efficiency of each commuter rail system and its relationship to individual system characteristics during the study period are also analyzed. Finally, case studies of historic energy efficiency of individual commuter rail systems with longer operating histories and reporting data over the majority of the study period are contrasted against more recent start-up systems. While many systems outperform the energy efficiency of a typical light-duty vehicle, there are others that, due to a variety of system parameters and characteristics, fail to achieve a load factor great enough to make them more attractive than the highway mode on a gross average level. It is hoped that highlighting trends and variation in commuter rail energy efficiency will allow policymakers to make more informed decisions regarding the environmental benefits of rail as an urban transportation mode.