Vehicle Emissions Research at NC State University

Quantification of Variability and Uncertainty in On-Road and Nonroad Vehicle Emission Factors

Remote Sensing

Measurement of Real-World, On-Road Emissions  Using a Portable Instrument

More recently, under sponsorship of the U.S. EPA’s Office of Air Quality Planning and Standards and under two US EPA Science to Achieve Results (STAR) grants, NCSU has expanded the uncertainty analysis of Mobile5 to include temperature correction factors (Frey et al., 1999), which was reported at the 1999 CRC on-road vehicle emissions workshop, and has developed probabilistic estimates of lawn and garden equipment emission factors (Frey and Bammi, 2002).  Similar work has been completed for construction, industrial, and agricultural nonroad emission factors (Frey and Bammi, 2002).

NCSU has conducted two remote sensing studies.  One focused on school bus emissions (Frey and Eichenberger, 1997) and was sponsored by the NCDOT.  The other involved simultaneous measurement of vehicle emissions using remote sensing and traffic parameters using an area wide video detector (Rouphail et al., 2000) and was sponsored by the Transportation Research Board ITS-IDEA program.

Currently, NCSU is pioneering the real world applications of portable on-road emissions instruments to evaluate the real world impact of traffic control measures on vehicle emissions (Frey et al., 2000; Rouphail et al., 2001, Frey et al., 2001a).  The final report of a more than two year study involving on-road measurement of tailpipe emissions of carbon monoxide (CO), nitric oxide (NO), and hydrocarbons (HC) for the purpose of evaluating the real-world effects of changes in signal timing and coordination and of traffic congestion is available on line (Frey et al., 2001b).  The study also provides new data regarding real world tailpipe emission rates during acceleration, cruise, idle, and deceleration driving modes.

In January 2002, NCSU completed a draft report for the U.S. EPA's Office of Transportation and Air Quality regarding recommendation of strategies for on-board emission data analysis and collection for the New Generation Model, which will succeed MOBILE6 (Frey et al., 2002).  The final report is not yet available.

For more information on vehicle emissions projects at NCSU, please visit our web site or contact Dr. Chris Frey at frey@eos.ncsu.edu or (919) 515-1155.

A publications list is given below.  Many of the publications are available on-line as Adobe Acrobat PDF files.

Frey, H.C., M.D. Kini, S.R. Ranjithan, and S.Y. Fu, “Uncertainty, Bias, and Variability in Emission Factors for Light Duty Gasoline Vehicles,” Paper No. 96-108B.03, Proceedings of the 89th Annual Meeting (held June 23-28 in Nashville, TN), Air and Waste Management Association, Pittsburgh, Pennsylvania, June 1996.

Frey, H.C., and D.A. Eichenberger, “Quantification of Uncertainty in Remote Sensing-Based School Bus CO and Hydrocarbon Emission Factors,” Paper No. 97-RP143.07, Proceedings of the 90th Annual Meeting (held June 8-13 in Toronto, Canada), Air and Waste Management Association, Pittsburgh, Pennsylvania, June 1997 (CD-ROM).

Frey, H.C., and D.A. Eichenberger, Remote Sensing of Mobile Source Air Pollutant Emissions: Variability and Uncertainty in On-Road Emissions Estimates of Carbon Monoxide and Hydrocarbons for School and Transit Buses, FHWY/NC/97-005, Prepared by North Carolina State University for North Carolina Department of Transportation, Raleigh, June 1997.  Retrieve this report as a PDF file (1.3 MB).

Frey, H.C., “Variability and Uncertainty in Highway Vehicle Emission Factors,” Emission Inventory: Planning for the Future (held October 28-30 in Research Triangle Park, NC), Air and Waste Management Association, Pittsburgh, Pennsylvania, October 1997, pp. 208-219. Retrieve A Reprint of this Paper as an Adobe PDF File (43 KB)

Kini, M.D., and H.C. Frey, Probabilistic Evaluation of Mobile Source Air Pollution: Volume 1, Probabilistic Modeling of Exhaust Emissions from Light Duty Gasoline Vehicles, Prepared by North Carolina State University for Center for Transportation and the Environment, Raleigh, December 1997.

Frey, H.C., R. Bharvirkar, R. Thompson, and S. Bromberg, “Quantification of Variability and Uncertainty in Emission Factors and Inventories,” Conference on the Emission Inventory, Air and Waste Management Association, Pittsburgh, Pennsylvania, December 1998. Retrieve A Reprint of this Paper as an Adobe PDF File (58 KB)

Frey, H.C., N. Rouphail, A. Unal, and J. Colyar, "Emissions and Traffic Control:  An Empirical Approach," Presented at CRC On-Road Vehicle Emissions Workshop, San Diego, CA, March 27-29, 2000.  Retrieve a Reprint of this Paper as an Adobe PDF File (71 kB).

Unal, A., R.H. Dalton, H.C. Frey, and N.M. Rouphail, “Simultaneous Measurement of On-Road Vehicle Emissions and Traffic Flow Using Remote Sensing and an Area-Wide Detector,” Paper No. 99-712, Proceedings of the 92nd Annual Meeting  (held June 20-24 in St. Louis, MO), Air and Waste Management Association, Pittsburgh, Pennsylvania, June 1999 (CD-ROM).  Retrieve a Reprint of this Paper as an Adobe PDF File (63 kB).

Frey, H.C., R. Bharvirkar, and J. Zheng, “Quantification of Variability and Uncertainty in Emission Factors,” Paper No. 99-267, Proceedings of the 92nd Annual Meeting  (held June 20-24 in St. Louis, MO), Air and Waste Management Association, Pittsburgh, Pennsylvania, June 1999 (CD-ROM).Retrieve a Reprint of this Paper as an Adobe PDF File (61 kB).

Frey, H.C., R. Bharvirkar, J. Zheng, Quantitative Analysis of Variability and Uncertainty in Emissions Estimation, Final Report, Prepared by North Carolina State University for Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC, July 1999. Retrieve this report as a PDF file (2.8 MB)

Rouphail, N.M., H.C. Frey, A. Unal, and R. Dalton, "ITS Integration of Real-Time Emissions and Traffic Management Systems," IDEA Project No. ITS-44, Prepared by North Carolina State University for the IDEA Program, Transportation Research Board, National Research Council, Washington, DC. May 2000. Retrieve this report as a PDF file (5 MB).

Zheng, J., A. Unal, and H.C. Frey, "Variability and Uncertainty Analysis of CO Exposure to Vehicle Passengers During Cold-Start, Proceedings of the 93rd Annual Meeting of the Air & Waste Management Association, Salt Lake City, Utah, June 18-22, 2000.

Rouphail, N.M, H.C. Frey, J. Colyar, and A. Unal, "Vehicle Emissions and Traffic Measures:  Exploratory Analysis of Field Observations at Signalized Intersections," Proceedings, 80th Annual Meeting of the Transportation Research Board, Washington, DC, January 2001.  Download Adobe Acrobat File

Frey, H.C., N.M. Rouphail, A. Unal, and J. Colyar, "Measurement of On-Road Tailpipe CO, NO, and Hydrocarbon Emissions Using a Portable Instrument," Proceedings, Annual Meeting of the Air & Waste Management Association, Pittsburgh, PA, June 2001Download Adobe Acrobat PDF File (107 kB)

Frey, H.C., N.M Rouphail, A. Unal, and J.D. Colyar, "Emissions Reduction Through Better Traffic Management:
     An Empirical Evaluation Based Upon On-Road Measurements," FHWY/NC/2002-001, Prepared by NC State
     University for NC Department of Transportation, Raleigh, NC, December 2001 (368 pages total).  Download Adobe Acrobat PDF File (6.35 MB)

H.C. Frey and S. Bammi (2002a), " Quantification Of Variability and Uncertainty In Lawn And Garden Equipment NOx and Total Hydrocarbon Emission Factors," Journal of the Air & Waste Management Association, accepted January 2002 for publication (pending).

H.C. Frey and S. Bammi (2002b), " Probabilistic Nonroad Mobile Source Emission Factors," ASCE Journal of Environmental Engineering, tentatively accepted pending revisions, as of January 2002.

Frey, H.C., A. Unal, and J. Chen, "Recommended Strategies for On-Board Emission Data Analysis and Collection for the New Generation Model," Draft Final Report, Prepared by NC State University for Office of Transportation and Air Quality, U.S. Environmental Protection Agency, Ann Arbor, MI.  January 2002 (not yet available in final form).