HEAVY-DUTY VEHICLE CHASSIS DYNAMOMETER TESTING FOR EMISSIONS INVENTORY

CRC Project No. E-55/59

Leaders:    S. H. Cadle

                  H. Maldonado

Scope and Objective

The objective of this project is to characterize current in-use heavy-duty (HD) emissions in urban areas in a manner that can be used to assess the accuracy of the current particulate matter (PM), oxides of nitrogen (NO_x), and other emission factors used in mobile source inventory models.

Current Status and Future Program

A request for proposal was issued by CRC in late 1999 for Project E-55 and following review of proposals, the project was delayed until further coordination between potential sponsorship was completed.  For example, DOE requested a year-long statistical review before proceeding.  A new project was then established by combining regulated emissions testing (E-55) with more detailed chemical analysis of the exhaust (E-59).  Sponsors for the E-55/59 project included CARB, EPA, EMA, DOE/NREL, and SCAQMD.  DOE/NREL conducted a statistical analysis to estimate the size of the database needed to meet the project objectives and issued a Final Report where emission factor uncertainty is reported as a function of the test fleet size.  DOE and CARB (through CRC) also prepared a statistical analysis report on performing chemical mass balance (CMB) assessments of diesel and gasoline emissions.  CMB uncertainties could not be quantified in this study.  The statistical analysis reports are posted on the CRC website.

One of the main objectives of Project E-55 was to develop improved heavy-duty (HD) diesel urban emissions factors of PM and NO_x that can be applied to emission factor models for HD diesel vehicles.  Data also yielded a better understanding of the relative impacts from light-duty (LD) versus HD mobile sources to the total urban emissions inventory.  CARB joined CRC to fund an expanded project scope to blend objectives from CRC Project E-59 to conduct detailed chemical analysis of the gaseous and particle phase emissions. The final project approach and scope were developed through detailed discussions among the potential sponsors. 

A request for proposal for the primary E-55/E-59 effort was issued in February 2001. Proposals were reviewed in March 2001 and the technical research panel selected WVU to lead the study with assistance from Desert Research Institute (chemical characterization) and the California Trucking Association (vehicle recruitment).  The first phase of the project was initiated in August 2001 in Southern California.  Data generated from this project have been used in CRC Project E-64 and by CARB in their mobile emission factor model for estimating HD vehicle emission levels.  EPA has been working on analysis of continuous PM data collected with a Tapered Element Oscillating Micro Balance (TEOM) for use in MOVES.

The Phase 1.5 effort included special chemical analysis of PM emissions as well as a collection of data at higher loads than obtained in the Phase 1 work.  The impact of engine control computer chip reflash on emissions was also studied in Phase 1.5. Phase 2 and Phase 3 efforts tested both HD and MD vehicles. Testing was completed in June 2005.

WVU's Final Report on E-55/59-2, "Heavy-Duty Chassis Dynamometer Testing for Emissions Inventory, Air Quality Modeling, Source Apportionment and Air Toxics Emissions Inventory," issued in July 2005, is posted on the CRC website. Additional detailed speciation data were collected in Phase 2.  An article focusing on the idle emissions was published in the October 2006 issue of the JAWMA.

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