INCORPORATION OF RELIABILITY INTO NIGERIAN EMPIRICAL MECHANISTIC PAVEMENT ANALYSIS AND DESIGN SYSTEM (NEMPADS)

Thesis Overview

<p> </p><p><strong>INTRODUCTIO</strong>N</p><p>1.1 &nbsp; &nbsp; &nbsp; &nbsp;<strong>BACKGROUND</strong></p><p>Traditionally, flexible pavement thickness design has been accomplished through empirically based procedures. One well-known procedure, the American Association of State Highway and Transportation Officials (AASHTO,1993) method, was based upon the AASHTO Road Test held in Illinois between 1958 and 1960. The design procedure utilized empirical relationships developed from the AASHTO road test and is therefore limited to the conditions of that test. In fact, all empirically based methods share the same common disadvantage in that they are limited to the conditions and observations of the particular road sections on which the procedure was based. This fact may require engineers to extrapolate outside the original inference space, which could be problematic.As a result of this limitation, many pavement sections failed prematurely while other sections far outlived their design lives(Rutherford, 2012)</p><p>Conversely, Empirical-Mechanistic (M-E) design is more robust since it combines the elements of mechanical modeling and performance observations in determining the required pavement thickness for a set of design conditions. The Empirical-Mechanistic Empirical-Mechanistic based method of pavement design is based on the mechanics of materials,which relates inputs such as wheel loads to output such as pavement response.The response is then used to predict pavement distresses(including cracking)and other performance based laboratories and field testing outcomes.In essence, M-E design has the capability of changing and adapting to new developments in pavement design by relying primarily on the mechanics of material (Timm<em>et al</em>, 1999).</p><br> <br><p></p>