Comparison of Driving Schedule Project Level MOVES Emission Factors to Empirical Data

摘要

The U.S. Environmental Protection Agency's Motor Vehicle Emissions Simulator (MOVES) model has a capability to estimate emission factors for selected vehicle source categories, model years, calendar years, ambient conditions, and driving schedules using a project level analysis feature. A driving schedule is a second-by-second sequence of vehicle speed and road grade, from which Vehicle Specific Power (VSP) is calculated. Driving schedule average emission rates in grams per mile are estimated based on the distribution of driving schedule time spent in operating mode bins denoted by ranges of VSP and speed. As part of a larger research effort, the potential for linking MOVES or simplified summaries of MOVES output with traffic simulation models is being explored. Thus, there is a need to evaluate the sensitivity of MOVES emission factors with respect to variation in driving schedules, vehicle characteristics, and ambient conditions. For this purpose, real-world vehicle activity, fuel use, and emissions data for CO_2, CO, NO, and hydrocarbons were measured for four selected routes in the Research Triangle Park, NC region using a portable emissions measurement system (PEMS), on-board diagnostic (OBD) data logger, and geographic positioning system with barometric altimeter for approximately ten light duty gasoline vehicles ranging from compact sedans to large pickup and sport utility vehicles. The real-world driving schedules and ambient conditions observed in the field were entered into MOVES. The relative variation in road segment and cycle average emission rates from MOVES are compared to those from the empirical data. The implications of the results regarding the response of MOVES to real world variations in driving conditions, and regarding applicability of MOVES for estimation of energy use and emissions in conjunction with microscale traffic simulation models, is discussed.