Mechanistic Basis for Permit Fee Decision of Superloads Traveling on Low-Volume Roads Using Structural Damage Evaluation

Superloads, including “Implements of Husbandry” and “Superheavy Loads” transporting significant amounts of heavy agricultural and industrial products, frequently travel on county or municipal roads designed for low-volume traffic to avoid interrupting highway traffic flow by their slow-moving behavior and wide vehicle widths. The non-standardized loading configurations and high gross vehicle and axle weights of superloads have significant potential for causing unexpectedly greater distress on low-volume roads than the general vehicle classes categorized for U.S. roads by the Federal Highway Administration. To evaluate the impact of superloads on paved and granular roads designed for low-volume traffic, a mechanistic road structural and damage-associated cost analysis is needed for predicting unexpected damage induced by various types of superloads, and to provide a logical basis for superload permit fee decisions. In this study, a layered elastic theory-based road and pavement analysis was performed to quantify damage to flexible pavements and granular roads caused by superloads. Costs associated with damage to flexible pavements and granular roads subjected to a single pass of various superload types were also derived and compared through multivariate life cycle cost analysis. The potential permit fees for each type of superload traveling under different road conditions were then suggested by calculating damage-associated costs related to traffic, road structure, material, and treatment types.