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The performance of road network in PMGSY will be significantly influenced by degree of maintenance and the evaluation of pavement performance involves a study of the functional behavior of that pavement. In the functional behaviour study, different types and degrees or severity of distress are evaluated. The time series distress data are used to predict the pavement performance. Based on performance prediction models, it is possible to select the best alternative rehabilitation or maintenance measure. The Highway Design and Maintenance Standards Model (HDM-III), developed by the World Bank had been used for over two decades to combine technical and economic appraisals of road investment projects, and to analyze maintenance and improvement strategies. The HDM-4 incorporates three dedicated applications tools for project level analysis, road work programming under constrained budgets, and for strategic planning of long term network performance and expenditure needs.

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