Two separate samples were collected from each road surface
representing different antecedent dry periods to account for
changes in sample composition. Past research studies have found
that total dust build-up in the initial period is rapid and tends to
reach equilibrium in around seven to nine dry days (Egodawatta
and Goonetilleke, 2008). Consequently, sampling times were selected
such that the antecedent dry period for one sampling episode
was less than 8 d and the other greater than 8 d.
Additionally, the road surface texture depth was measured according
to the recommendations provided by FHWA (2005).