Fugitive Dust Handbook

6.0   UNPAVED ROADS

When a vehicle travels on an unpaved surface such as an unpaved road or unpaved parking lot, the force of the wheels on the road surface causes pulverization of surface material. Particles are lifted and dropped from the rolling wheels, and the road surface is exposed to strong air currents in turbulent shear with the surface. The turbulent wake behind the vehicle continues to act on the road surface after the vehicle has passed. The primary PM emission estimation methodology presented in the fugitive dust handbook is taken from Section 13.2.2 of AP-42 last updated in December 2003. This methodology includes two categories of unpaved roads: industrial unpaved roads and public unpaved roads. Alternate methodologies adopted by the California Air Resources Board in August 1997 for non-farm roads and farm roads are also included in the fugitive dust handbook. The sample control measure cost-effectiveness calculation spreadsheet presented for this source category involves watering of the unpaved road surfaces at an industrial facility twice a day during an 8-hour work day.