Driver and Road Type Effects on Light-Duty Gas and Particulate Emissions

Abstract

An instrumented minivan on a 30-mi (48-km) test route was used to measure second-by-second vehicle operating characteristics as well as tailpipe particulate and gas emissions. The research objectives were (a) to quantify the variability of gas and particulate emissions between 12 drivers and (b) to measure the relative emissions levels on freeways, signalized arterials, rural two-lane arterials, and local roads. The results reaffirm that individual drivers significantly affect emissions levels. All emissions concentrations were also systematically related to road type. Furthermore, drivers could be grouped by emissions level, but these groupings differed by pollutant and by road type. More data are needed to elucidate driver–road type interactions and to characterize the regional driver pool for more robust microscale emissions models. The relative importance of driver type compared with the importance of other factors known to affect emissions needs to be quantified. Finally, two key issues were identified as affecting the accuracy of instantaneous emissions measurements: instrument response time effects on data alignment and accurate quantification of the full range of on-road exhaust flow rates.