Analysis of Modal Emissions From Diverse In-Use Vehicle Fleet

Research Program. This paper describes the initial phase of a longterm project with national implications for the improvement of transportation and air quality. The overall objective of the research is to develop and verify a comprehensive modal emissions model that accurately reflects the impacts of a vehicle’s operating mode. The model is comprehensive in the sense that it will be able to predict emissions for a wide variety of light-duty vehicles (LDVs, i.e., cars and trucks) in various states of condition (e.g., properly functioning, deteriorated, malfunctioning). Other efforts and further background on modal emission modeling have been described elsewhere (1) and elsewhere in this Record by An et al. A specific modal emissions testing protocol has been developed that reflects both real-world driving and specific modal events associated with different levels of emissions. This testing protocol (described later in this paper) is being applied to more than 300 vehicles to provide the foundation for the modal emissions model. As a preliminary step, the test cycle has been applied to an initial fleet of 30 vehicles, where at least 1 vehicle falls into each of the 28 defined vehicle/technology categories. The preliminary analysis of the initial test fleet is described.