Design of flexible road pavements as affected by drainage conditions

Abstract

Road pavement use is determined primarily by the vehicle type that will use the facility. Climatic conditions affect the behavior of pavement materials, as well as the sizes of traffic loads. The relative strength loss in a layer due to its drainage characteristics and the total time it is exposed to near-saturation moisture conditions is represented by drainage coefficients. The Transportation Laboratory of Democritus University of Thrace in Xanthi Greece has developed an algorithm for a computer-based procedure towards the calculation of the layer thickness of flexible pavements. The design equation used is that described by the American Association of State Highway and Transportation Officials. The present work deals with the effect of drainage on the total thickness of the structure as it directly influences the cost of large infrastructure projects like roads. The output of different cases solved is presented in table and schematic form. Changes in technology related to pavement design and construction practices will necessitate revisions to currently used computing techniques. There is a need for computerized methodologies for thickness design of flexible asphalt pavements (granular base course) for a wide variety of pavement uses providing users the capability to conduct structural analysis of special pavement structures. Improvements in computing times which will affect in a way the cost of computerized methods available to engineers are to be suggested in the near future. Empirically supported pavement designs used nowadays in Greece require modifications based on regional experience and on a better assessment of the drainage conditions prevailing in each area crossed by a roadway project. Since design considerations constantly change, it is obligatory to shift towards more sophisticated design methods.