Locomotive prime mover engine emission rates are typically measured at steady-state for discrete throttle notches using an engine dynamometer weighted by a standard duty cycle. However, this method may not represent real-world locomotive emissions. A method for in-use measurement of passenger locomotives, using a portable emissions measurement system (PEMS), was developed to estimate duty cycle average emission rates. We conducted 48 measurements of one-way trips between Raleigh and Charlotte, NC, on 7 locomotives and 18 sets of measurements in the rail yard (RY). Real-world duty cycles differed from those used for regulatory analyses, leading to statistically significant lower cycle average NOx and HC emission rates. Compared to RY measurements, notch average NOx emission rates measured over-the-rail (OTR) at the highest two notch settings were, on average, 19% lower for four locomotives. At the highest notch, OTR CO2 emission rates were, on average, 12% lower than RY rates for five locomotives. For a more accurate representation of real-world emission rates, OTR measurements are preferred. However, using steady-state notch average RY emission rates and standard duty cycles may be tolerable for some applications. OTR versus RY cycle average emission rates typically differed by less than 10%.

For environmental emissions certification, locomotive prime mover engines undergo rigorous measurements with the use of federal reference methods (FRMs). However, there are nonregulatory reasons for engine emissions measurement, such as to compare relative differences in fuel use and emissions as a result of engine rebuild or between engines in a fleet. Portable emissions measurement systems (PEMSs) are widely used for highway vehicle and nonroad construction equipment but have had limited locomotive applications. The objectives are to (a) demonstrate an approach for quantifying locomotive emission rates with a PEMS during dynamometer and rail yard engine load tests, (b) compare the emissions measured in dynamometer versus rail yard load tests, and (c) assess the relative change in fuel use and emissions from engine rebuild. Measurements were conducted on 3,000-hp prime movers, including an EMD 16-645 for a GP40 and two EMD 12-710s for F59PHs. Fuel use and PEMS-based emission rates for nitric oxide, carbon monoxide, hydrocarbons, and particulate matter were compared between dynamometer and rail yard load tests and with data from previous literature. Fuel use and oxides of nitrogen (NOx) emission rates after engine rebuild were lower for the GP40 prime mover, and the fuel use and NOx emission rates for the F59PH rebuilt engines were lower than those of the rebuilt GP40 engine. PEMS is not a substitute for locomotive FRMs if compliance certification is needed but provides useful data for comparative assessment.

Few data are available regarding the effect of biodiesel on exhaust emission rates of two-stroke engines used in many passenger locomotives. Using a portable emissions measurement system (PEMS), duty cycle average nitrogen oxides (NO), hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM), and carbon dioxide (CO) emission rates were measured for three locomotives operating on ultra-low sulfur diesel (ULSD) and soy-based B10, B20, and B40 biodiesel blends. Measurements were conducted in the rail yard (RY) and over-the-rail (OTR) during passenger service. Compared to ULSD, B20 biodiesel had statistically significant average emission rate reductions in the RY of 58% for CO, 45% for PM, and 6% CO and OTR of 59% for HC, 50% for CO, 26% for PM, and 5% for CO. The average differences in NO emission rates for both the RY and OTR, and HC in the RY, were not statistically significant. The OTR findings typically agreed qualitatively with the RY findings; however, OTR provides a better basis for estimating the real-world impact of fuel switching. The results indicate substantial potential to reduce in-use locomotive emissions for existing older locomotives, with the exception of NO.

Avoided emissions attributable to the reduction in personal automobile trips for passenger rail riders are quantified based on real-world measurements. The North Carolina Department of Transportation (NCDOT) sponsors the Piedmont passenger rail service between Raleigh and Charlotte, NC. Per passenger-kilometer locomotive emissions were quantified based on portable emissions measurement system measured exhaust concentrations and duty cycles, or the fraction of trip time spent in each throttle notch setting of the prime mover engine, from 68 one-way trips of six Tier 0? and Tier 1? locomotives, and actual ridership data. Motor Vehicle Emissions Simulator (MOVES) software was used to estimate light-duty gasoline vehicle (LDGV) emission factors. Moving a passenger from an LDGV to a Piedmont train would lead to a net reduction in carbon dioxide (CO 2 ) and carbon monoxide (CO) emissions by 44-94 %, respectively, between Raleigh and Charlotte, based on the assumption that the driver is the only LDGV passenger. However, locomotive nitrogen oxides (NO x ), hydrocarbons (HC), and particulate matter (PM) emission factors were 4-11 times higher than for the LDGV, respectively. Delays for either the train or highway vehicles did not substantially alter the key findings. If a Tier 4 locomotive was used, NO x , PM, and HC emission rates would be 90-99 % lower than current NCDOT locomotives. The use of realworld data representative of actual train operations provides an accurate basis for comparing rail and personal vehicle energy use and emissions and for identifying key factors affecting variability in the comparison.

The purpose of this study is to demonstrate methodology for characterization of a plug-in hybrid electric vehicle (PHEV), taking into account gasoline and electricity consumption and emissions associated with each. Field measurements were made of a Toyota Prius with 1.5 liter gasoline engine, Hybrid Synergy Drive (HSD) system with an original battery, and retrofitted Hymotion plug-in system with a second battery. The PHEV initially operates in charge-depleting mode (CD) until the Hymotion battery charge reaches a set point, after which it operates in chargesustaining mode (CS) using only the original battery. Three systems were used for in-use monitoring of the PHEV: (a) electronic download from the hybrid control system interface for factors such as battery charge, voltage, and current, and on-board diagnostic (OBD) data such as engine RPM, manifold absolute pressure, intake air temperature, road speed, and others; (b) portable emission monitoring system (PEMS) measurement of exhaust gas concentrations; and (c) GPS monitoring of coordinates and of altitude using a barometric altimeter. These data were used to characterize the activity of the PHEV, the energy flow associated with the batteries and diesel engine, and the tailpipe emissions. Results are presented based on in-use data collection for real-world driving cycles, in order to demonstrate methodology for integrated analysis of a plug-in hybrid system. Fuel economies for CD and CS modes were approximately 60 and 40 mpg. The indirect electricity emission factors were estimated based on EPA eGRID and National Emission Inventory data. An engine load-based model based on vehicle-specific power (VSP) was developed to explain variation in battery current, fuel use and emission rates based on the real-world data.