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The Advanced Collaborative Emissions Study (ACES) program required the use of representative heavy-duty diesel engine activity. This need resulted in an engine test schedule creation program, and a schedule of engine modes representative of modern truck usage was developed based on data collected from engines in trucks operated through the heavy heavy-duty diesel truck (HHDDT) chassis schedule. The ACES test schedule included four active modes of truck operation including creep, transient, cruise, and high-speed cruise (HHDDT_S). This paper focuses on Phase 2 of the program, which was to validate and demonstrate the use of the ACES modes in a test cell. Preliminary testing was performed using a 1992 Detroit Diesel Corporation heavy heavy-duty diesel engine (HHDDE) on only the transient mode. On the basis of these results, each mode was modified slightly to suit implementation in a test cell. The locations of "closed throttle" points in the modes were determined through careful examination of the data. These closed throttle points were simulated during testing by adding negative set point torque values to the input file. After modification, all modes were tested during a final ACES modes demonstration period using a 2004 Cummins ISM HHDDE, obtaining three runs for each mode. During testing, carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), particulate matter (PM), and hydrocarbon (HC) emissions were measured, and engine control unit (ECU) data were recorded. The new ACES modes did not adopt the Federal Test Procedure (FTP) regression criteria. New regression criteria for acceptability of a run were determined for each mode using the data obtained during testing. [ABSTRACT FROM AUTHOR]

Alternative fuels and technologies offer potential for reducing emissions in public transportation. These potentials were explored by determining emissions levels and fuel consumption from the U.S. transit bus fleet and comparison of hypothetical scenarios in which implementation of specific alternative fuels and technologies is considered. Impacts from current transit bus procurements were also evaluated. Emissions benefits above and beyond the natural course of transit bus procurements were examined for new diesel buses running on ULSD fuel, diesel-electric hybrid buses, gasoline-electric hybrid buses, compressed natural gas and biodiesel. According to the analysis, reductions in emissions of CO, NMHC, NOx, PM and CO2, as well as fuel consumption, may be attained, and diesel hybrid buses yield the largest reductions in CO2 emissions and are the only technology to reduce fuel consumption relative to the present fleet. Introducing diesel-electric hybrid buses in 15% of the U.S. transit bus fleet would reduce annual end-use emissions by nearly 1,800 tons of CO, 400 tons of NMHC, 4,400 tons of NOx, 200 tons of PM, 491,400 tons of CO2, and fuel consumption by 50.66 millions of diesel gallons. [ABSTRACT FROM AUTHOR]

In-use emissions from vehicles using heavy-duty diesel engines can be significantly higher than the levels obtained during engine certification. These higher levels may be caused by a combination of degradation of engine components, poor engine maintenance, degradation or failure of emissions after-treatment devices, and engine and emissions system tampering. A direct comparison of in-use vehicle emissions with engine certification levels, however, is not possible without removing an engine from the vehicle in order to perform engine dynamometer emissions testing. The goal of this research was to develop a chassis test procedure that mimics the engine performance, and as such the expected emissions levels, from the engine certification emissions test prescribed in the U.S. Code of Federal Regulations. Emissions measurements were taken from two engines during testing on an engine dynamometer using the transient heavy-duty Federal Test Procedure (FTP). Additionally, each engine was installed in an appropriate vehicle, and emissions measurements were taken using a chassis dynamometer while employing a vehicle driving schedule intended to match closely the instantaneous torque and speed schedule of the engine FTP. Engine and chassis testing was performed with the engines in stock (unmodified) condition as well as in several modes to simulate either tampered or poorly maintained conditions. The use of a chassis test as a predictive tool for determining whether an engine in a vehicle would pass the engine certification test has proven to be worthwhile. Analysis of the data shows that identification of chassis-mounted engines with NO[subx] emissions above certification levels is possible by employing engine-specific correction factors. In the case of PM emissions, significant data scatter allowed only the identification of gross PM emitters. Engine tampering and poor maintenance can raise PM and NO[subx] emissions, and these increase can be correctly... [ABSTRACT FROM AUTHOR]

The article focuses on the effort of U.S. government agencies in identifying and prioritizing the research needs for the country's transportation sector. Over the past years, particulate matter has become one of the most important air quality problems in the country. Furthermore, the transportation planning agencies have a vested interest in understanding particulate matter problems and contributing to their effective control. In addition, non-attainment areas are required to developed a state implementation plan.