Vehicle classification data especially trucks has an important role in both pavement maintenance and highway planning strategy. An advanced microelectromechanical system (MEMS) accelerometer for vehicle classification based on axle count and spacing was designed, tested, and applied to the pavement. Vehicle-pavement interaction was collected by the vibration sensor while vehicle axle count and spacing were calibrated later. Collected vibration data also used to analyze the pavement surface condition and compared with simulation using dynamic loading analysis. Laboratory tests using MMLS3 device to verify the accuracy of MEMS accelerometer and reaction under different surface condition were tested. An algorithm for calculating axle spacing and axle count was developed. Acceleration of different pavement surface condition were analyzed and compared with simulation results, the influence of surface condition to the pavement acceleration was concluded. / Master of Science

" The determination of strain is an important step when using a mechanistic-empirical structural design, such as the AASHTO 2002 Design Guide. This thesis investigated the use of accelerated pavement testing system on Hot Mix Asphalt pavements to determine actual transverse and longitudinal strains under loads of varying frequency at different temperatures. A Model Mobile Load Simulator (MMLS3) was used in this study. Laboratory compacted pavement slabs were instrumented with thermocouples for monitoring the pavement's temperature, and with strain gauges in transverse and longitudinal directions at the bottom surface to measure strain. The slabs were subjected to loading by the MMLS3, running at different speeds. The pavement slab and accelerated loading equipment were enclosed in an environmental chamber to control temperatures during testing. Strains were also determined from layered elastic analysis after determining modulus values by two different methods - Resilient modulus testing and Witczak’s dynamic modulus equation. Comparisons of pavement strains calculated through the use of layered elastic design software and actual strains obtained during loading were made. The test results have shown a significant difference between strain values obtained using an instrumented pavement slab and those obtained with the use of standard resilient modulus values or dynamic modulus values determined by using a typical layered elastic design model. To avoid the discrepancies, two approaches are proposed - The first is modeling strain with accelerated pavement testing and the second one is using a correction factor. "

In this dissertation, studies of accelerated pavement testing have been discussed and the relative advantage of using the Model Mobile Load Simulator 3 (MMLS3) has been illustrated. A test protocol of using MMLS3 as a fatigue characterization tool has been proposed and validated by testing several Hot Mix Asphalt slabs. Data acquisition was performed with strain gauges placed in different directions under slabs in controlled environmental condition. Analysis of data showed the effect of wheel load on fatigue behavior of pavement in terms of strain history response, cracking and reduction of modulus. Performance curves showing relation between initial strain and failure loads were developed and were compared with the performance curves obtained from standard method. It has been shown that rutting related excessive permanent strain due to movement of particles under wheel path can affect fatigue performance of Hot Mix Asphalt pavement. Method of estimation of time dependent strain has also been developed to predict observed strain.