This paper details the results of an external validation effort for the hot stabilized option currently included in the Mobile Emissions Assessment System for Urban and Regional Evaluation (MEASURE). The MEASURE model is one of several new modal emissions models designed to improve predictions of CO, HC, and NO x for the on-road vehicle fleet. Mathematical algorithms within MEASURE predict hot stabilized emission rates for various motor vehicle technology groups as a function of the conditions

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... nder which the vehicles are operating, specifically various aggregate measures of their speed and acceleration profiles. Validation of these algorithms is performed on an independent data set using three statistical criteria. Statistical comparisons of the predictive performance of the MEASURE and MOBILE5a models indicate that the MEASURE algorithms provide significant improvements in both average emission estimates and explanatory power over MOBILE5a for all three pollutants across almost every operating cycle tested. In addition, the MEASURE model appears to be less biased, the most critical model performance measure for point-estimate forecasts, than MOBILE5a.