Characterization of Exhaust Emissions from Heavy-Duty Diesel Vehicles in the HGB Area - Final Report (0-6237-1)

The relative contribution of heavy-duty diesel vehicles (HDDVs) to mobile source emissions has grown significantly over the past decade, and certain vehicles identified as high emitting vehicles (HEs) contribute disproportionately to the overall HDDV emissions. It is critical for state and local transportation agencies in nonattainment areas such as the Houston-Galveston-Brazoria (HGB) area to address this component of the fleet to mitigate emissions effectively from the component. For this study, a total of 30 HDDVs were selected from City of Houston (COH) fleet based on opacity testing for HEs and random selection for non-HEs. With the selected 30 vehicles, driving and idling emission testing were performed to characterize their emissions with respect to vehicle classes, types (HE or non-HE), and model years. The measured emission testing results were analyzed and compared with Motor Vehicle Emission Simulator (MOVES) estimates as well as among vehicle classes and types. In general, emissions of HEs were higher than non-HEs. Replacing HEs with non-HEs or vehicles complying with new emissions standards could reduce their emissions significantly. This report contains detailed results including gaseous, PM, and air toxic emissions testing results and MOVES estimates.