Purpose Modeling represents the art of translating problems from an application area into tractable mathematical formulations whose theoretical and numerical analysis provides insight, answers and guidance useful for the originating application. The purpose of this paper is to determine the causal causes of schedule overrun and cost escalation of highway projects in Egypt in order to be used as independents variables in mathematical models for predicting the percentages of schedule overrun and cost escalation of such projects in Egypt. Design/methodology/approach A survey of a randomly selected samples yielded responses from 40 owners, 15 consultants and 56 contractors. The survey includes 38 schedule overrun factors and 26 cost escalation factors. The effectiveness degree of the identified factors has been identified by the triangle fuzzy approach. Findings The results of the survey show that “contractor’s technical staff is insufficient and ineligible to accomplish the project” is the most important cause of schedule overrun, while the major cause of cost escalation is inadequate preparation of the project concerning planning and execution. Originality/value The main contribution of this study is predicting the percentages of schedule overrun and cost escalation of highway projects in Egypt. Through the application of the linear regression analysis method and statistical fuzzy theory, four predictive models have been developed and it has been noted that the linear regression-based model shows prediction accuracy better than statistical fuzzy-based model in predicting percentages of schedule overrun and cost escalation.

Purpose Quality measurement is the trigger for quality improvement. Indeed, what gets measured gets done. The real scope of quality improvement in construction projects is the difficulty and-maybe-lack of quality measurement methods. The purpose of this paper is to identify the factors influencing the quality performance of highway projects in Egypt. Furthermore, this paper also contributes to develop models to measure the quality level of these projects. Design/methodology/approach A literature review is conducted to compile a list of factors influencing the quality of highway projects. The resulting list of factors is subjected to a questionnaire survey which was sent to owners, consultants and contractors of highway projects in Egypt. Furthermore, linear regression analysis and statistical fuzzy approaches are adopted for modeling process. Findings The survey results show that availability of experienced staff in the owner’s and contractor’s teams during the project execution, asphalt quality and type used in the construction process, pavement is not designed according to the regional conditions, and contractor’s labors and equipment capability are among the most important factors influencing quality performance. Originality/value The main contribution of this study is to develop models to measure the quality of highway projects in Egypt. The first model is based on the linear regression analysis, while the second one is based on a statistical fuzzy approach which is a hybrid approach from the fuzzy logic and regression analysis. Validation of the models reveals that the linear regression and the statistical fuzzy models can accurately assess expected quality of any future highway projects at confidence levels 68.97 and 87.44 percent, respectively.

While project management success focuses upon the processes and the successful accomplishments of cost and time objectives, product success deals with the quality of the final product. Recently, quality of the constructed highway has been considered highly important reason for the pavement response and its design life. The main objective of this paper is to improve the management of highway projects in Egypt by determining the most important factors influencing the quality performance of this industry. In total, 39 factors that may influence the quality of highway projects have been defined through a detailed literature review. The factors are tabulated in a questionnaire form, which is sent out to 13 owners of divided highways, 27 owners of regional roads, and 15 consultants. The analysis of the respondents' perspectives using fuzzy triangle approach shows that the most important factors affecting the quality are availability of experienced staff in the owner's and contractor's teams during the project execution; efficiency of the owner's inspection team; clarity of responsibilities and roles for each owner, consultant, and contractor; pavement which is not designed according to the regional conditions (e.g., soil type, temperature, and traffic volume); and asphalt quality and type used in the construction process.

Abstract:The temperature of the asphalt concrete AC is one of the most important environmental factors that influences flexible pavement performance. The possibility hazard of temperature change raises attention in how it may affect the deterioration rates (deflection, strain and stress distributions) in flexible pavement and how pavement service life would be changed as a result. A change in the AC temperature directly influences the stiffness of the asphalt-bound layers, which modifies the stress statues inside the pavement. This alteration in stress can influence the stiffness of the underlying unbound layers since they generally show stress reliance. Due to these relations are nonlinear, the additional pavement life lost at higher than average temperature is not replaced by savings at lower than average temperature. For that, the deterioration amount are overvalues when average pavement temperatures are used for determining the asphalt stiffness. The objective of this research was to study the pavement temperatures throughout the year in Egypt on performance and life of seven pavement sections with different stiffness or thickness using mechanistic-empirical method to investigate the most influential characteristic under temperature change for improving the design of pavement structures. The results revealed the significance of the impact that climate change may have on the performance service life of flexible pavements. These changes may impact the pavement life cycle cost and thus their impact on future maintenance requirement should be investigated.

In Long Term Pavement Performance (LTPP) assessment process , the specific pavement studies were designed to investigate the factors affecting pavement rehabilitation such as overlay thickness (51 and 127mm), asphalt overlay materials (raw compared with adding 30% reclaimed asphalt pavement (RAP)) and surface curing type before rehabilitation (low and heavy). In this study, data from 4 sites were taken to perform analysis where each site consists of 8 sections (4 sections with raw materials and another 4 sections using 30%RAP). Each section was 152.4 m long and 3.66 m wide. These sites were selected due to their similar climate to Egypt. Four performance indicators were chosen including fatigue cracking, longitudinal cracking, rutting, and roughness. A statistical analysis using the paired t-tests, p-values and analysis of variance (ANOVA) were achieved to determine the priority in performance and the significance in variation. The results that based on practical observations have indicated that the RAP sections achieved similar/ better performance as compared with raw sections especially at higher thickness except for rutting. The climate had no obvious effect on fatigue cracking development while dry climate provided higher longitudinal cracking and roughness progress for RAP sections. Statically, the variation in pre-overlay curing (from low to heavy) had the highest statistical effect on fatigue cracking increasing, while rutting and roughness progresses weren't clearly affected by variation in climate, thickness or curing.