62calculating the required overlay thickness at the project level. The ability to predict the future pavement remaining strength can be potentially useful in developing long-term rehabilitation strategies and management policies at the network level.Prediction of pavement remaining strength is directly related to the long-term performance of pavements. Two types of models have been widely used in predicting the long-term performance of pavements: probabilistic and deterministic. The probabilistic model predicts the future pavement condition with some degree of uncertainty, whereas the deterministic model predicts it with certainty (7). The probabilistic model that was extensively used by several researchers to predict pavement performance is the discrete time Markov model (8-12). The Markov model can be used with homogenous or nonhomogenous transition chains. The homogenous chains require the same transition matrix, whereas the nonhomogenous chains can deploy a different transition matrix for each chain.The prediction outcome of pavement performance is typically represented by means of a performance curve, which depicts pavement deterioration rates in relation to service time. Predicted performance curves were used in yielding optimum pavement design and performing optimum life-cycle analysis (13,14). The area falling under the performance curve has long been recognized as a direct measure of the pavement relative structural capacity (4,5,13,14). Therefore, the area under the performance curve at any given service time can be directly related to the pavement remaining strength, considering a specified service life. It is proposed to use the discretetime Markov model to predict pavement distress ratings for use in generating distinct performance curves (models). The predicted performance models will be used in estimating the pavement remaining structural capacity. The predicted remaining structural capacity can be used in estimating the required overlay design thickness, developing pavement rehabilitation strategies, and establishing rehabilitation project priority scheduling.
RESEARCH OBJECTIVESThere are three main objectives for this research paper:1. Predicting the performance curve (model) for a particular pavement project using stochastic modeling; 2. Predicting the flexible pavement remaining strength and overlay design thickness using layer structural capacity adjustment factors with the principal asphalt layer adjustment factor derived from the generated performance curve; and 3. Developing empirical stochastic-based models for predicting remaining strength and overlay design thickness to be used by the practitioners in pavement rehabilitation and management.A pavement's remaining strength is predicted from initial pavement strength by means of layer structural capacity adjustment factors. "Initial pavement strength" is defined as the total structural capacity associated with the asphalt concrete and underlying granular layers estimated by appropriate relative strength indicators such as the gravel equival...