Evaluation of flexible pavement design methods

With rapid motorisation and industrialisation in Egypt,bituminous pavement surfacings are becoming more and more common in the country, However the empirical design of bituminous pavement layers is still based on experience and empirical strength tests, whereas trends now are towardusing theoretical and semitheoritical methods which treats special conditions for each design area. So this study aimsto evaluate the various methods of pavement structural design which are used around the world, and to conductsensitivity analysis of design ariables for one of the most common methods (AASHTO Design Method of New Pavement and Surfacing 1986) [1] using its computer program (DNPS86) [2]and using values and condition suitable for Egypt to check its suitability of using in Egypt. The analysis revealedthat the performance of the pavement is the most important factor which affects the pavement required strength and itscost. Also the strength of subgrade soil has a higher effect on strength and cost of the pavement than the quality of base and subbase layers.