Infrastructure projects frequently encounter challenges related to cost overruns, schedule delays, scope deviations, and quality deficiencies, particularly in complex rehabilitation projects operating under strict operational constraints. This paper investigates the Impact of Integrating Project Management Techniques on Improving the Performance of Infrastructure Projects, with an application to Greater Cairo Metro. A quantitative descriptive-analytical approach was adopted using data collected through a structured questionnaire from 242 valid respondents drawn from a population of 650 participants involved in the Fire Protection System Rehabilitation Project on Greater Cairo Metro Line 1. The data were analyzed using the Statistical Package for the Social Sciences (SPSS) 25 and Analysis of Moment Structures (AMOS) through reliability and validity tests, Confirmatory Factor Analysis (CFA), Structural Equation Modeling (SEM), and Path Analysis. The results revealed a statistically significant positive effect of integrating project management techniques on infrastructure project performance. The findings also demonstrated statistically significant positive effects for each of the four techniques investigated individually. Among the standardized path coefficients, Earned Value Management (EVM) had the numerically largest coefficient, followed by Program Evaluation and Review Technique (PERT), Six Sigma, and Work Breakdown Structure (WBS). The integrated application of these complementary techniques was associated with improvements in budget control, schedule adherence, scope adherence, and quality improvement. This study contributes by empirically examining both the overall integrated relationship and the individual relationships of EVM, WBS, PERT, and Six Sigma with infrastructure project performance within a real-world infrastructure rehabilitation project and provides practical guidance for improving the performance of similar projects operating under safety and operational constraints.