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Road surface profile is an important factor that affects the dynamic responses of the vehicle, which in turn affects pavement responses. In this study, a complete two-dimensional (2D) axle-tire-pavement interaction finite-element model was developed to investigate the effects of a rutted surface on near-surface pavement responses. The results indicate there is a significant difference in tire-pavement contact stress distributions between a rutted surface and a flat surface. The presence of a rutted surface increases both the propensity for top-down cracking and the severity of instability rutting. The observed trend indicates that the greater the existing rut severity is, the more likely it is for top-down cracking and increased rutting to occur. [ABSTRACT FROM AUTHOR]

The effects of truck tire types on near-surface pavement responses were evaluated via finite element anyalysis. First, three truck radial tires (11R22.5, 425/65R22.5, and 445/50R22.5) were modeled based on the tire geometries and specifications from the tire manufactures. Accordingly, tire-pavement interaction models were developed. These models were then verified by comparing predicted contact stresses with measured ones to make sure models can be used for further evaluation purpose. The results indicated that the super single (425/65R22.5) tire produced greater contact stress and more damage to the pavement in terms of top-down cracking and instability rutting, while new generation wide-based tire (445/50R22.50) induced approximately the same damage as the standard dual assembly tested (11R22.5). [ABSTRACT FROM AUTHOR]

Abstract: The Florida Department of Transportation (FDOT) Materials Office has recently acquired a heavy vehicle simulator (HVS) and constructed an accelerated pavement testing (APT) facility which uses this HVS. An investigation was conducted to evaluate the operational performance of the HVS, and to determine its most effective test configurations for use in evaluating the rutting performance of pavement materials and/or designs under typical Florida traffic and climate conditions. Five trial runs with the HVS used a super single tire with a load of 4082kg, tire pressure of 793kPa and a wheel traveling speed of 12.9km/h. These five trial runs used different combinations of wheel traveling direction (uni-directional or bi-directional), total wheel wander and wander increments. The uni-directional loading was found to be a more efficient mode for evaluation of rutting performance using the HVS. As compared with the bi-directional loading mode, the uni-directional mode produced substantially higher rut depths for the same number of wheel passes and also for the same testing time duration. When the bi-directional loading with no wander was used, imprints of the tire treads were observed on the wheel track. It was found that using a loading mode with wander smoothened out the imprints of the tire treads considerably. The uni-directional loading mode with 10cm wander using 2.5cm increments was selected to be used for evaluation of rutting performance based on consideration of testing efficiency and realistic rutting results. [Copyright &y& Elsevier]

Falling weight deflectometer (FWD) testing has been done extensively in the past to assess structural condition and determine the moduli of pavement layers. The set of modulus values for pavement layers obtained from the backcalculation process may not be accurate even though the computed and measured deflection basin may match within tolerable limits. Extensive interpretation is involved in obtaining the layer moduli of these pavements. Guidelines and tools are provided for calculating layer moduli for flexible pavements. FWD interpretation has become increasingly challenging because more and more of our roads have experienced multiple milling operations and overlays. The characteristics of the structure such as damaged layers, thickness variation, and temperature changes can overwhelm the deflection data, having a far more significant effect than those induced by structural layer stiffness. This study emphasizes that proper interpretation of FWD data involves a complete evaluation of all available data, including core data, roadway data, and section-specific distress information. Evaluating multiple FWD measurements along the sections allows for the evaluation of consistency and assures reasonableness of interpretation. [ABSTRACT FROM AUTHOR]