This paper presents a study on developing a structural model of Mitigation measures and overrun factors in Saudi Arabian Railway Metro construction projects. A literary review found 24 measures related to mitigations and 58 overrun factors. These factors were used as the main content of the questionnaire’s development. The questionnaire was distributed among the Railway/Metro construction practitioners to evaluate each factor based on the 5-points Likert scale. The data collected from the questionnaire survey was used in the development of the structural equation model. The criteria for the selection of experts was that they should have more than five years of experience in Saudi Arabian Railway metro construction projects. The total 263 no of questionnaire survey forms distributed among experts working on the Riyadh metro project and 220 no of questionnaire were found correct to use for the analysis. The first part of the analysis was to identify the demography of the experts which describe that all the experts have substantial experience in the railway metro projects, also were qualified and have a senior role/designation in their organization that makes them suitable to answer the questions and give the researcher the confidence to fully rely on their views. After demography, the reliability of the data was checked through SPSS which found the data satisfactory and can be used further . Before final modelling through PLS SEM, an exploratory factor analysis (EFA) was performed to reduce the no. of mitigations and over-run factors and grouped them in clusters to get the required results for the model. EFA clusters 24 factors of mitigation into four groups which are Construction Planning, Construction Execution, Design Control and Commercial and identified 54 overrun factors clustered into five groups which are Financial, Design, Construction Execution, Construction Planning and Contract Administration. Based on the final form of the model, construction execution and commercial mitigation category which consists of several causative factors has significant impact on overrun factors of railway/metro construction projects. This finding is validated using advanced techniques of multivariate analysis which will benefit all parties involved in construction projects for controlling overrun factors. As a result, this study adds to the body of knowledge in the railway construction sector by offering an empirical assessment of overrun factors and mitigation strategies in Saudi Arabia.