On-Road Remote Sensing of Automobile Emissions in the Omaha Area: Year 2, September 2004

work from Omaha, additional measurements have been made in Tulsa, OK and a final analysis of the combined work will be reported separately. Any conclusions stated in this report concerning comparisons with other E-23 sites and data should be considered preliminary until completion of all of the work. The University of Denver conducted a five-day remote sensing study in the Omaha, Nebraska area in September of 2004. The remote sensor used in this study measures the ratios of CO, HC, and NO to CO 2 in motor vehicle exhaust. From these ratios, we calculate the percent concentrations of CO, CO 2 , HC and NO in the exhaust that would be observed by a tailpipe probe, corrected for water and any excess oxygen not involved in combustion. Mass emissions per mass or volume of fuel are also determined. The system used in this study was configured to determine the speed and acceleration of the vehicle, and was accompanied by a video system to record the license plate of the vehicle. Five days of fieldwork, September 13-17, 2004, were conducted on the uphill interchange ramp from westbound I-680 to westbound Dodge Rd. A database was compiled containing 20,778 records for which the states of Nebraska and Iowa provided registration information. All of these records contained valid measurements for at least CO and CO 2 , and 20,695 records contained valid measurements for HC and NO as well. The database, as well as others compiled by the University of Denver, can be found at www.feat.biochem.du.edu. Due to road reconstruction, Omaha proved to be a difficult city to find a repeatable measurement site. Two different locations were used in 2002. The first a curved uphill off-ramp from westbound I-680 to eastbound Dodge Rd. (this site is directly across from this year's site) was abandoned because of insufficient traffic. The second an uphill on ramp from 84 th St. to eastbound I-80 was not repeated this year because its driving mode proved too difficult to compare with other E-23 sites. Because of these differences, direct comparisons between the three sites are not made in this report. The mean CO, HC and NO emissions for the fleet measured in this study were 0.20%, 176ppm and 267ppm, respectively. The emissions measurements in this study exhibit a gamma distribution, with the dirtiest 10% of the measurements responsible for 79.8%, 60.8%, and 56.8% of the CO, HC, and …