Numerical Model to Optimize Selection of Unpaved Roads for Dust Suppressing Chemical Treatments: Case Study

Abstract

This study developed a model to select the optimum sections of unpaved roads for chemical treatments as dust suppressants within a limited budget. In the state of Wyoming, more than 19,312 km (12,000 mi) of roads are unpaved. Because Wyoming is a leading producer of coal, oil, and natural gas, its unpaved roads have more traffic that results in significant dust emissions. To reduce these emissions, the state currently uses CaCl2 and MgCl2 as dust suppressants. Because its budget is limited, all 19,312 km (12,000 mi) of unpaved roads cannot be treated every year. A previous study concluded that traffic volumes, the percentage of fines passing through a #200 sieve, and annual rainfall make significant contributions to the generation of dust. Considering these factors, this study developed a model that identifies which unpaved roads should be treated given the limited budget. Because the resulting model is nonconvex, an evolutionary solving method was used to identify the best set of projects for chemical treatment. As a case study, the proposed model was implemented on a small network of 23 unpaved roadway segments.