Analysis of Trends in Commuter Rail Energy Efficiency
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.Copyright © 2014 by ASME
Comparison of Emissions from Light-Rail Transit, Electric Commuter Rail, and Diesel Multiple Units
The United States is experiencing a revival of interest in diesel multipleunit (DMU) passenger railcars. At the same time, communities are questioning whether diesel makes good sense as they compare the diesel multiple unit with electric rail modes such as light rail or electric multiple units. This study quantifies the emissions into a region from diesel multiple units and the electricity generation for electric rail modes, for oxides of nitrogen (NOx), an ozone precursor; particulate matter (PM); volatile organic compounds (VOCs), another ozone precursor; carbon monoxide (CO); and carbon dioxide (CO2). The study found that emissions attributable to electric rail modes are highly variable and depend on the cleanliness of the electricity generated. The dirtiest electricity pollutes orders of magnitude more than the cleanest. The study conclusion is that emissions from diesel multiple units and electric rail modes are not dramatically different on a per seat mile basis and that the exact comparison will de...
Ridership trends of new start rail projects
This research reports on the ridership trends of new start Light Rail Transit (LRT) projects implemented in the last two decades. These systems are colloquially referred to as "new start" systems. The purpose of the research presented here is to look at the process of maturation of these systems in terms of ridership trends. Each system's ridership is examined, and system extent in terms of route miles and service miles also is examined. The research attempts to discern the impact of service expansion associated with the system synergies that might result from increased accessibility. Performance is evaluated by reviewing ridership changes as LRT systems grow and comparing them with changes in service supply. This review of the National Transit Database data indicates that ridership trends for new start LRT projects matured relatively quickly, with subsequent growth driven by system extent and service levels. The initial rapid maturation is partially attributable to the high levels of attention light rail lines receive when they are under development and implemented, as well as the inherent physical presence that LRT provides for transit. It is interesting to note that the LRT systems, even the more mature systems, are a modest share of the urban area's total transit service, with the most successful systems providing approximately 30% of total regional transit trips. LRT investments may be very important to a community by stimulating attention and investment in public transit. LRT implementation has helped several communities expand public transit use; however, it has not resulted in dramatic changes in the role that public transit plays in regional mobility in the respective communities. While LRT is playing an important role in expanding opportunities for transit use, even LRT system development is a lengthy process with a mixed record in terms of providing substantial growth in transit ridership.