| Abstract
| - Traditional emissions inventories for trucks and buseshave relied on diesel engine emissions certification data,in units of g/bhp-hr, processed to yield a value in g/milewithout a detailed accounting of the vehicle activity.Research has revealed a variety of other options forinventory prediction, including the use of emissions factorsbased upon instantaneous engine power and instantaneousvehicle behavior. The objective of this paper is to providetabular factors for use with vehicle activity information todescribe the instantaneous emissions from each heavy-duty vehicle considered. To produce these tables, a largebody of data was obtained from the research efforts ofthe West Virginia University-Transportable Heavy DutyEmissions Testing Laboratories (TransLabs). These datawere available as continuous records of vehicle speed (hencealso acceleration), vehicle power, and emissions ofcarbon monoxide (CO), oxides of nitrogen (NOX), andhydrocarbons (HC). Data for particulate matter (PM) wereavailable only as a composite value for a whole vehicletest cycle, but using a best effort approach, the PM wasdistributed in time in proportion to the CO. Emissions values,in g/sec, were binned according to the speed andacceleration of a vehicle, and it was shown that theemissions could be predicted with reasonable accuracyby applying this table to the original speed and accelerationdata. The test cycle used was found to have a significanteffect on the emissions value predicted. Tables werecreated for vehicles grouped by type (large transit buses,small transit buses, and tractor-trailers) and by range ofmodel year. These model year ranges were bounded by U.S.national changes in emissions standards. The result isthat a suite of tables is available for application to emissionspredictions for trucks and buses with known activity, oras modeled by TRANSIMS, a vehicle activity simulation modelfrom Los Alamos National Laboratories.
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