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In-service emissions measurements were conducted on two package delivery trucks: one model year 2008 FCCC MT-55 conventional diesel and one model year 2012 FCCC MT-55 hydraulic hybrid (HHV). Mass emissions of CO2, CO, NOx, PM, and THC from the HHV and the conventional diesel test vehicle were each measured under conditions closely simulating normal package delivery operation. The HHV demonstrated a 29.4% improvement in fuel economy and a 17.4% reduction in CO2 emissions compared to the conventional diesel vehicle. The HHV showed its best potential in operating areas characterized by low driving speeds and high number of stops (“pick-up and delivery”) with a 40.5% improvement in fuel economy and a 21.2% reduction in CO2 emissions.

In order to demonstrate the performance of a retrofitted selective catalytic reduction (SCR) system while also addressing the issues associated with greater use of biodiesel, a 2005 International 9200i tractor owned by the City of Santa Monica was retrofitted with a titania-vanadia-tungsten catalyst and a urea dosing system supplied by Extengine Systems, Inc. This tractor was operated under normal service conditions within the City of Santa Monica refuse collection and transportation fleet. An on-board emissions measurement system supplied by Engine, Fuel, and Emissions Engineering, Inc. was installed on the vehicle; it measured the emissions and fuel use of the vehicle while it operated on ultra-low-sulfur diesel (ULSD), 20% biodiesel (B20), and 99% biodiesel (B99) on consecutive days.

Portable systems capable of measuring mass exhaust emissions while riding on-board vehicles and mobile equipment are relatively new. Their advantages include lower measurement costs, the ability to measure emissions under realistic operating conditions (including conditions that are difficult to simulate in the laboratory), the ability to measure emissions where no traditional laboratory is available, and applicability to a broader range of engines and vehicles than those addressed by traditional laboratory methods (e.g. construction machinery). However, on-board methods have not yet been fully accepted in the air quality community. This is due in part to concerns over their reproducibility and accuracy, and the adequacy of the corresponding quality assurance and quality control measures.

Emissions of particulate matter (PM) and oxides of nitrogen (NOx) from heavy-duty engines used in road vehicles and mobile equipment are of critical concern to air quality planners. Accurate measurement of these emissions is needed both for emission inventory purposes and for the development and validation of emission control measures. These emissions cannot adequately be predicted from laboratory tests on new engines. This paper reports the development of the Ride-Along Vehicle Emission Measurement (RAVEM) system. Based on the constant volume sampling (CVS) principle, the RAVEM system can accurately and repeatably measure mass emissions of NOx, CO2, and PM from an engine exhaust pipe while “riding along” on the vehicle or equipment under test. In most cases, this can be done without removing the vehicle from service. RAVEM test results have been shown to correlate very closely with those of conventional CVS emission laboratories.

Emissions from heavy-duty vehicles in real operation on the road often differ greatly from those that would be projected from laboratory testing. Reasons for this difference include variations between laboratory and real-world driving conditions, wear and deterioration that are not effectively modeled by laboratory tests, inadequate or inappropriate in-use maintenance, and the use of “cycle-beating” strategies and “defeat devices” by engine manufacturers. This paper analyzes data showing in-use emissions from heavy-duty diesel and natural gas vehicles tested using various driving cycles on chassis dynamometers. It is shown that average in-use emissions of particulate matter (PM) and oxides of nitrogen (NOx) from late model heavy-duty diesel engines are much higher than predicted by current emission models, and greatly exceed the emission standards to which these engines were certified.