The objectives of this work are to: (1) quantify spatial variability in locomotive fuel use and emission rates (FUERs) and identify factors differentiating emission hotspots from non-hotspots; (2) predict spatially varying real-world locomotive FUERs; (3) develop a software tool for estimating the fuel use and emissions of a typical Piedmont train operation; (4) develop a study design for locomotive exhaust measurements with the Blended After Treatment System (BATS); and (5) develop a study design for quantification of passenger train in-cabin pollutant concentrations. Locomotive FUERs, including CO2, CO, hydrocarbon, NOx, and particulate matter emission rates, and train speed, train acceleration, track grade, and track curvature were quantified based on over-the-rail measurements, using portable emission measurement systems, for diesel passenger rail service on the Amtrak Piedmont route. A locomotive fuel use and emissions model was developed to estimate FUERs at high spatial resolution. The model was calibrated based on locomotive power demand (LPD), which accounts for the physics of resistive forces opposing train motion such as acceleration, track grade, and track curvature. The model was integrated into the Piedmont Passenger Train Fuel Use and Emission Estimator Software (PPTFUEES) tool in Microsoft Excel.
Results show that there is large variability in FUERs over short distances. For example, FUERs among a pair of adjacent 0.25 mile track segments differed on average by a factor of 2 to 60, depending on location and pollutant species. Emission hotspots comprised only 20% of the route length but comprised 40% to 50% of the total fuel use and emissions along the entire route. Acceleration, grade, and speed are key factors in distinguishing segments as hotspots versus non-hotspots. The LPD-based model is capable of predicting precise and accurate FUERs at high spatial resolution. Acceleration, grade, and drag resistances are the highest relative contributors to LPD regardless of train consist. Real-world train speed trajectories are identified that reduce trip fuel use and emissions by 13% to 49% compared to the average. Trip fuel use and emissions can be reduced by dispatching energy-efficient and low-emitting locomotives and operating with 20% blend of biodiesel on trajectories with low LPD. The PPTFUEES is able to estimate fuel use and emissions for each station-to-station segment and the entire route of a typical Piedmont train operation. The software user manual and examples of applications are provided in this final report. In addition, this report also includes a study design for railyard and over-the-rail locomotive exhaust measurements with BATS, and a study design for measurements and modeling of in-cabin air quality for passenger rail.
