Long-Term Study on the Cost-Effectiveness of Dust Control and Untreated Aggregate-Surfaced Resource Roads

A long-term study of treated and untreated aggregate resource roads in Canada was conducted. The objective was to investigate the cost-effectiveness of annual dust control treatments where the hypothesis is that annual applications may prolong aggregate life. Seven sections along two road segments with different traffic levels were studied over five years. A survey of road users revealed that 88% agreed that the treated sections were safer because of the increase in visibility and quicker dust settlement times. Evaluation of surface aggregate indicated some aggregate wear but there were no significant differences between treated and untreated sections. The source and quality of crushed aggregate has an impact on road performance. The condition of the running surface did not indicate any major performance differences between the treated and untreated sections. Regardless of treatment, age, or aggregate sources, a general downward trend in Unsurfaced Road Condition Index was observed, indicating wearing course degradation over time. The study revealed a strong correlation between traffic volume and maintenance intensity. Moderately higher travel speeds were measured on the treated versus untreated sections. When the cost of treatment and maintenance was compared with historical costs, the dust control scenario was more expensive. However, when log hauling cost savings from increased travel speeds were introduced, the dust control was approximately cost neutral in low traffic scenarios and moderately better for high traffic. If non-quantifiable benefits, such as increased safety, were to be considered, application of dust control treatment is recommended.