Abstract: “Learning development effect plays an important role in planning and scheduling of repetitive projects. Several mathematical models, or learning curves, have been proposed to investigate improvement in productivity as a function of the number of units produced. Deciding the best-fit learning curve model for the activity under consideration is a management challenge. In this paper, the best-fit learning curve model for describing past performance of gas pipeline construction in Egypt is presented. Data were collected from real-life projects that are constructed in different types of land and having different size, length, pipe diameter and under various weather conditions. Only welding activity is considered in the present work because it is a labourintensive activity. Cumulative average data is used to represent collected data, which gives a smooth curve as well as avoids scattered data. The commercial Statistical Package for Social Science (SPSS) is used to calculate Pearson's coeffici”

Keywords: Repetitive Projects, Gas Pipeline Construction, Learning Development Effect, Learning Curve Models, Cumulative Average Data.