Pavement Design Literature Review

This literature review aims at reviewing pavement design literature which will be focused primarily on three main methods used currently and in the past. These three methods are the Mechanistic, Empirical and Empirical-Mechanistic design methods. Reviewing these methods are important as they will justify which is the most desirable method of design. According to (Croney & Croney, 1998), a pavement design is a process whereby a design process associates materials with which a road will be constructed to the traffic generated on that road in the most cost effective way so that the design life requirements can be met. Furthermore, (SAPEM, 2013) states empirical designs are designs based on experience and observations, mechanistic designs are designs

a rather empirical design approach. With the invention of the car and the growth in traffic, tyre pressures and high speeds as cars developed over the years, it was necessary to change the way designs were done. Designs could not be based on experience only as performance had to be better understood and more predictable, and road functionality had to be defined. Knowledge of structural behaviour and pavement distress in relation to time was required and this led to the AASHO road test being developed. Although developed in the 1950’s, AASHO road test are still relevant today as it is still used to meet the demands of ever increasing traffic growth by developing satisfactory pavement design procedures. In intent of the AASHO tests was to understand the relationship between performance and loading. During these investigations a few road design parameters was defined, with road serviceability, Present Serviceability Rating (PSR), Present Serviceability Index (PSI) and the concept load equivalency all being defined using this

The physical causes is distinguished as the mechanistic part and empirical part is used to determine the relationship by observation of the performance. Furthermore, it goes on to state that the Mechanistic-Empirical Design Guide (MEPDG) designed to update the 1993 AASHTO Guide of Pavement Structures. The AASHTO Guide was mainly based on empirical observations from the old AASHO Road Test that began about 60 years ago.
(Erlingsson, 2007), states that Mechanistic-Empirical design methods are in development in many countries and the critical objective is to obtain information on factors that affect pavement performance such as axle loading, material properties, weather and environmental conditions, that can be used for modelling purposes. Furthermore, he goes on to state that information is needed to confirm these methods if an acceptable relationship between real performance and estimations are to be