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
STEM K-12 Outreach as the Root of Transportation Education: Experiences from the Railway Engineering Field
Demand for graduates with rail transportation expertise remains strong in North America, particularly in engineering and technical fields. Over the past decade, various activities by the American Railway Engineering and Maintenance-of-way Association and rail-focused University Transportation Centers have slowly re-established a railway engineering academic community. Railway courses are now offered at two dozen universities in the United States (U.S.), and, for the first time in decades, several universities offer specific degrees in railway engineering. Despite this progress, challenges remain, such as raising student awareness of rail industry career paths. Since most railway engineering courses are senior-level electives, many students are already committed to other engineering disciplines before they are exposed to railway concepts. To raise student interest in rail courses and satisfy industry demands for internships, students must be introduced to railway concepts before they decide on the direction of their studies. One approach to directing more rail-aware students into engineering programs is rail-themed outreach to K-12 students. Railways still hold a fascination for many young people as complex, multidisciplinary systems, and numerous interesting science, technology, engineering, and math (STEM) concepts can be demonstrated through the lens of railway transportation. Interactive rail-themed classroom activities can illustrate STEM topics while highlighting rail career opportunities and reinforcing railway transportation. This paper reviews rail-themed K-12 STEM outreach activities being undertaken by universities and the strong partnerships between industry and academia required to grow future generations of railway professionals.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.