Revisiting the Drainage Coefficient of the AASHTO93: A Method for Improving Local Flexible Pavements Design

Abstract

The AASHTO93 guide is widely used in pavement design and is considered the primary reference in road construction and management for many countries worldwide. One important parameter used in the AASHTO93 design method is the drainage coefficient, which considers the impact of saturation on the stiffness of granular materials. However, selecting this parameter can be associated with high uncertainty in practice. With the knowledge gained from applying this methodology and advancements in current research on granular materials, it is possible to revise this parameter to achieve optimal results. This work aims to review the basics of the drainage coefficient and introduce a more logical approach to define the proper parameter for local conditions. The goal is to enhance pavement design practices in administrations that utilize the AASHTO93 method, particularly those with no intention of transitioning to advanced techniques like the mechanistic-empirical approach or where alternative approaches are still minimal.