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. Final report, 1 July 1995-31 December 1996
The purpose of this study is to develop on-road emission factor estimates for carbon monoxide (CO) and hydrocarbon (HC) emissions from school and transit buses. Data were collected at 10 locations selected based upon logistical needs for deployment of the remote sensing device and expectations regarding traffic volumes for the selected bus fleets. A total of 1,340 valid remote sensing measurements of on-road emissions ratios of CO/CO2 and HC/CO2 were obtained for 265 diesel-fueled school buses, 36 gasoline-fueled school buses, 19 diesel-fueled transit buses of the Triangle Transit Authority (TTA), 3 gasoline-fueled buses of TTA, and 12 diesel-fueled transit buses at Raleigh Durham International Airport (RDU) over the course of 22 days of field work. Bus characteristics, including fuel economy data, were obtained from the Wake County public schools, TTA, and RDU. A mass balance combustion model was developed for the purpose of calculating emission factors in units of grams per gallon. Vehicle fuel economy data were used to calculate emission factors in units of grams per mile. Emission factors on both grams per gallon and grams per mile bases are reported for diesel and gasoline school buses and diesel transit buses. The variability in emissions are based upon individual measurements, and the uncertainty in fleet average emissions, were characterized using cumulative distribution functions and confidence intervals, respectively. There were orders-of-magnitude ranges of variability in individual emission factor estimates for each bus fleet. Estimates of emissions on an annual per-passenger basis are provided for North Carolina public school buses and TTA buses. Limitations of remote sensing and of the estimated emission factors are discussed, and recommendations are made regarding priorities for future data collection and analysis.
- Research Organization:
- North Carolina State Univ., Raleigh, NC (United States). Dept. of Civil Engineering
- OSTI ID:
- 529873
- Report Number(s):
- PB--97-192132/XAB
- Country of Publication:
- United States
- Language:
- English
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