Journal of Earth Sciences and Geotechnical Engineering
Dynamics of Dust Clouds Produced by Off-road Vehicle Driving
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Abstract
Field experiments were conducted in the Nellis Dunes Recreational Area (Nevada, USA) to study the dynamics of dust clouds produced by off-road vehicle (ORV) driving. Tests were performed with a 4-wheeler (quad), for 3 driving speeds between 24 and 40 km h-1 and for 7 different types of surfaces. Fine as well as coarse-grained surfaces were investigated in the tests. Results show that concentration of PM10 (particles <10 ìm, which are the most easily inhaled) behind an ORV can be as high as 160 mg m-3 or even more at nose level of quad drivers and passive recreants standing near an ORV trail. ORV generated dust clouds are characterized by a main wave of high concentration followed by an exponential decrease with irregularities (secondary waves) until background concentration has again been reached. Peak concentrations usually occur between 5 and 7 seconds after the passage of an ORV and are higher for silty surfaces than for sandy surfaces. Under no-wind and headwind conditions it takes at least one minute before PM10 concentration has returned to the background level. For tailwind the duration of elevated concentration is of the order of 30 seconds. For winds blowing obliquely to the driving path it is only a few seconds. Elevated PM10 concentrations may occur up to several hundreds of meters behind an ORV, even if no dust is visually noticeable. In-echelon driving is thus strongly dissuaded unless appropriate protection is worn against inhaling the dust.
