Approximately 110,000 km (68,400 mi) of granular roadways exist in the 183,500-km (114,000-mi) road network in the state of Iowa, and operation and maintenance of these roadways costs roughly US$270 million annually. The major maintenance costs of these roads are aggregate cost and hauling costs from the quarry to the site. Accordingly, acquiring a costeffective and high-performance surface material to be utilized in granular roadways can be a challenge. In this study, three conventional granular roadway materials and four coarser aggregate materials from different quarries were used to construct seven test sections to assess their relative performance and costs. The first three test sections were constructed with conventional materials, and the other four sections used optimum mixtures of the four coarse aggregate materials with the local conventional aggregate. The long-term performance and mechanistic behaviors of the different surface materials, including stiffness, changes in ride roughness, and dust production were evaluated for a period of 2 years. Using the resulting data, a mechanistic life-cycle benefit–cost analysis approach was developed to evaluate the use of coarse aggregate materials on granular roadways. The stochastic benefit–cost analysis results for different aggregate materials are presented in the form of probability density functions. Two different scenarios are presented based on the field test results, and the benefits in terms of dust production and surface ride quality are evaluated for each section.
Available at: http://works.bepress.com/jeramy_ashlock/22/