Effects of supersingle tire loadings on pavements

Due to their efficiency and economy, supersingle tires have gradually been replacing conventional dual tires in the trucking industry. According to recent studies, supersingle tires generate much higher vertical contact stresses than do conventional dual tires, resulting in larger deformations and more severe damage to the subgrade. In order to better assess the larger stresses generated by supersingle tires and their effect on the subgrade, analyses are done taking into account soil plasticity. In this paper, the effects of supersingle tires on subgrades for typical road cross sections are investigated using plane-strain two-dimensional and three-dimensional static and dynamic finite element analyses. The analyses focus on the sand and clay subgrades rather than on asphalt and base layers. The subgrades are modeled as saturated in order to investigate the effects of porewater pressures under the most severe conditions. The analyses suggest that current flexible pavement design methods are unconservative for the increased loads imposed by supersingle tires on the pavement system.