Development of a modal emissions model using data from the Cooperative Industry/Government Exhaust Emission test program

PDFTech ReportExhaust gasesPolluting gasesGround vehiclesSimulationAir qualityEmissions testingAcceleration (Mechanics)United StatesUniversity of South Florida. Dept. of Civil and Environmental EngineeringWayson, Roger L.Kim, BrianUniversity of Central Florida. Dept. of Civil and Environmental EngineeringAGR-IMPACTS-EnvironmentNTL-ENERGY AND ENVIRONMENT-Air QualityNTL-ENERGY AND ENVIRONMENT-Environment ImpactsNTL-HIGHWAY/ROAD TRANSPORTATION-HIGHWAY/ROAD TRANSPORTATIONVolpe National Transportation Systems Center, Technical Reference CenterThe Environmental Protection Agency\ue2\u20ac\u2122s (EPA\ue2\u20ac\u2122s) recommended model, MOBILE5a, has beenused extensively to predict emission factors based on average speeds for each fleet type.Because average speeds are not appropriate in modeling intersections or other scenariosinvolving intermittent travel, emission factors that are specific for vehicle operating modes(acceleration, deceleration, free-flow, and idle) have been studied in the past. Several modelshave been developed that use the concept of acceleration-speed products to serve as inputvariables to determine multipliers that can be used to modify constant speed emission factors.Although relatively simplistic, this process provides results that are considered more accuratethan constant speed emission factors. The Comprehensive Modal Emissions Model (CMEM)developed under sponsorship by the National Cooperative Highway Research Program(NCHRP) is based on a parameterized physical approach. While anticipated to be moreaccurate, the input requirements to the model are necessarily more complicated.This paper presents a new modal emissions model based on existing emissions data from theearly 1990s revision efforts of the Federal Test Procedure (FTP). The model updates the olderacceleration-speed product models that were based on data from the 1970s. Using secondby-second emissions data, several different forms of the modeling equations were developedand statistically analyzed for predicting multiplying factors for CO. A goal in developing thismodel is to serve as a comparison basis for the NCHRP model. The second and moreimportant goal is to use the model as part of a microscale traffic simulation model that predicts air quality near roadways