Characterizing the effects of driver variability on real-world vehicle emissions

Abstract

AbstractÐRecent studies on real-world automobile emissions measurements have not adequately addressed the question of whether driving style a ects emission levels. In this study, we hypothesized that given the same experimental conditions and a random selection of drivers, the variability associated with individual driving styles (e.g. intensity or duration of acceleration events) would produce statistically signi®cant di erences in measured emissions. To test this driver variability hypothesis, we conducted a ®eld study on 24 drivers in a single vehicle on a speci®ed route under low tra c conditions using on-board exhaust emission and engine operating data analyzers and tested for statistically signi®cant di erences in CO and NOx emissions between drivers. Our data show signi®cant (95% level) variations in carbon monoxide (CO) and oxides of nitrogen (NOx) emissions among the 24 drivers under driving conditions where we have controlled for driving route, tra c density and vehicle type. Since the ANOVA tests showed signi®cant di erences in emissions between drivers but the frequency of driving modes were very similar, this suggests that the intensity of vehicle operation within a give mode, not the modal frequency, explains the emissions variability between drivers. #

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