Vehicle-generated fugitive dust transport: analytic models and field study

Vehicle-generated road dust was measured under stable atmospheric conditions at a flat site in the Utah west desert, and the horizontal flux of the dust was calculated by integration of interpolation functions that are fit to the wind speed and dust concentration measurements at discrete heights. The site contained a uniformly spaced array of 2.5 m high×2.4 m×12.2 m roughness elements (cargo containers) simulating an urban setting. The dust measurement objective was to test the hypothesis that near-source removal of vehicle-generated dust may account for part of the reported systematic discrepancy between emission inventories based on AP-42 factors and receptor-based source apportionment studies. The horizontal flux of dust decreased to less than 15% of the initial value while traveling between measurement planes 3 and 95 m from the road, indicating significant near-source removal under the stable atmosphere and high surface roughness conditions of this field experiment. The magnitude of the flux was sensitive to assumptions about dust concentration and wind speed near the ground. The estimates for the flux at 3 m, obtained by integrating alternative interpolation functions, spanned the AP-42 value. Time-averaged data for meteorology, boundary layer turbulence, and dust concentration are provided to allow using the field observations for future theoretical analysis or numerical modeling studies.