The objective of this paper is to describe the development of the line source sorting model NETSEN II and its use in conjunction with the EPA's automobile exhaust emissions model analysis model. Speed-profile analogies from the Regional Air Pollution Study of the St. Louis air quality control region (AQCR), developed for use in the model emissions model, are used. The model emissions model was designed to calculate the amounts of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOX) emitted by individual automobiles or groups of automobiles stratified by age and geographic location. The NETSEN II is an updated version of NETSEN with additional variables and subroutines and the ability to test for the following roadway characteristics in defining a line source at any level of data refinement (a line source being the smallest segment of inventoried roadway depictable with a given specific set of attriputes): average daily traffic, five types of special typography, four types of capacity alternations, eight types of sensitive land uses, five types of activity centers, five types of progressive movement, channelization, functional classification, link distance, peak speed differences, truck and bus volumes, and volume-capacity (V/C) ratio. In this research, the inputs to NETSEN II are the appropriate uses control cards for selection of line sources and the network roadway inventory; and the output is a set of line sources that meet specified characteristics which is used as the project's first output, the second being the emission rates computed by the modal emissions model, the third the emission factors for trucks, and the fourth a control card to determine the total percentage of all trucks, the hours of the day for which emissions data are desired, and whether or not emissions are to be added to the grid totals of stored separately as hourly totals. With these inputs, line source emissions were computed. Besides NETSEN II itself, the data analysis and modeling efforts of the project yielded: development of a truly microscale emissions estimation modals which allows emissions to be analyzed as a function of highly localized traffic operating conditions and roadway descriptions through integration of NETSEN II and the modal emissions model; the ability to develop accurate analogies of speed-profile and emission characteristics for links that do not possess speed-profiled data; and thus an accurate and exhaustive statement of emissions obtained for line sources in the St. Louis AQCR.
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