# Application of Mechanistic Empirical Pavement Design Guide Software in Saudi Arabia
## 1 Introduction  
The modern day pavements in Saudi Arabia (KSA), and mostly all around the world, have experienced under-design due to financial constraints or unexpected traffic growth. The hot mix asphalt (HMA) pavement structures, also known as flexible pavements, require a more economic and suitable design as compared to other engineering structures. The engineers today face the challenge of building not only longer lasting stronger pavements but also in a restrained budget to full fill the demand of transporting people and goods from one place to another. Transportation has been playing a vital role in the advancement of the society, and the most widely used mode of transportation is the land mode and specifically highway mode. Therefore, a pavement not designed for a higher level of loading will fail earlier than the design life costing more money for repair. Currently, in KSA, AASHTO Guide for Design of Pavement Structure [1] along with the Marshall method are commonly used for structural design of asphalt pavements. These procedures are empirical, developed as long as half a century ago for much lighter traffic and low tire pressures compared to the existing conditions in KSA. Therefore, these procedures are incapable of providing reliable designs for existing heavy axle loads and tire pressure. AASHTO highway design method was not able to precisely predict paving efficiency; since the procedure was established using constrained testing of AASHTO roadways during the 1960s [2, 3]. The use of AASHTO procedure for designing asphalt concrete pavements in KSA has been under discussion since the very start of asphalt pavements. The mechanistic-empirical approach is promising but for it to produce satisfactory and cost-efficient asphalt mix design with appropriate equipment and local distress models its field verification has become essential. Actually, AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) does a great job of predicting paving efficiency using more factors of available local resources, such factors as current traffic loads and climatic conditions, in contrast to conventional systems of empirical design [4,5]. Using AASHTO MEPDG provides meaningful results, which significantly improved pavement design, as well as resulting in savings from selecting more cost-effective material mixtures [6]. There are very restrictive literature, focused on a single location, available that address the actual climate data prevalent in KSA to ensure precise design using the AASHTO MEPDG. Precisely, ascertaining climate data for four different real location region conditions in KSA is the subject of this research. The introduction of different models for hot mix asphalt (HMA) dynamic modulus (E*) prediction, focused on the implementation of the ME Design in the KSA by developing a database containing mechanical properties of a wide variety of HMA mixtures is not the focus of the study [7]. Different studies have been conducted to calibrate rutting and IRI models, and results reveal that the adjusted coefficients are appropriate because the new coefficients of the rutting models reduced the bias from 4.90 to 0.03 and SSE from 317.68 to 61.71 while the new coefficients of the IRI model reduced the bias and SSE from 0.44, 0.31 to 0, 0.03 respectively. The major focus is to analyze the variable temperature of the actual variable climatic conditions in different parts of KSA [8]. Another study aimed to prepare data for calibration of MEPDG in Central Saudi Arabia. The goal was to collect data for the design of asphalt pavement from the local conditions in Riyadh region [9]. [PERSON] also prepared a set of inputs required by the AASHTOWare for the central region of KSA. The validation of the AASHTOWare distress prediction models were conducted after calibration [10]. AASHTO MEPDG method is developed on mechanical and experiential basis [11]. It assumes that pavement can be modelled as a multi-layered elastic structure, and the design procedure carried out as a staged process over time.