Determination of PEMS Measurement Allowances for Gaseous Emissions Regulated Under the Heavy-Duty Diesel Engine In-Use Testing Program Part 3 – Results and Validation

Beginning in 2007, heavy-duty engine manufacturers in the U.S. have been responsible for verifying the compliance on in-use vehicles with Not-to-Exceed (NTE) standards under the Heavy-Duty In-Use Testing Program (HDIUT). This in-use testing is conducted using Portable Emission Measurement Systems (PEMS) which are installed on the vehicles to measure emissions during real-world operation. A key component of the HDIUT program is the generation of measurement allowances which account for the relative accuracy of PEMS as compared to more conventional, laboratory based measurement techniques. A program to determine these measurement allowances for gaseous emissions was jointly funded by the U.S. Environmental Protection Agency (EPA), the California Air Resources Board (CARB), and various member companies of the Engine Manufacturer's Association (EMA). This program was conducted at Southwest Research Institute^® (SwRI^®), and was directed by a Steering Committee comprised of representatives from all of the funding parties. In field validation testing was conducted by the Center for Environmental Research &

As part of a three paper series, this paper will focus on the final results of program. The results of the statistical model used in the program will be presented, as well as the model validation efforts, and the analysis of the results leading to the final measurement allowance values. Earlier papers focused on the laboratory test methods and on the details of the statistical methods.