A new study by the California State University Riverside Department of Mechanical Engineering offers engineers and planners new methods for assessing road dust and provides new baseline data on its scope and scale on the State Highway System.

The goal of this research was to deliver a more reasonable and realistic road dust emissions factor model and field testing means for freeways with high traffic volume.

For this project, a novel road dust collection system was designed that utilizes a modified van with a vacuum collection system that samples road dust on freeways. It was tested in a range of traffic flows from 1000 vehicles/hour to 14,000 vehicles/hour over the State Highway System. Based on the data collected at these locations, researchers designed a new mechanistic model for particulate matter emissions estimates. The van-based road dust collection system effectively sampled road dust on freeways without disrupting traffic.

The results provide Caltrans and other regulatory agencies with a new, efficient, and scalable method for assessing road dust impacts to air quality on highways and urban roads. If utilized further, this collection system and mechanistic model could extend Caltrans ability to test for road dust across the State Highway System and be used to develop a larger road dust model in the future. Such a model that more fully characterizes road dust existing conditions and how the pollutant levels change due to such factors like the increase of electric vehicles adoption, would provide these agencies a clearer understanding of the scope and scale of road dust and when to consider regulatory adjustments.

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