The New “Iron Triangle” of Project Management: Schedule, Cost and Value

Since the late 1960s, project management researchers have studied the factors contributing to project success, with Dr. Barnes introducing the “Iron Triangle” concept in 1969. Initially composed of scope, time, and cost, subsequent interpretations have varied, with quality, stakeholder satisfaction, risk management, and sustainability proposed as additional vertices. However, it is difficult to reach a consensus on the definitive concepts of the Iron Triangle. This study proposes a new Iron Triangle that incorporates the concept of “value” along with cost and schedule, consistent with Lean Construction principles. Through a comprehensive literature review and critical analysis, the study identifies systematically excluded dimensions of the traditional Iron Triangle, emphasizing stakeholder satisfaction, sustainability, and innovation. The research aims to understand how these dimensions enhance traditional project management models by integrating Lean Construction principles. The results reveal a dynamic relationship among cost, schedule, and value, challenging the traditional assumption of inverse proportionality. The proposed model emphasizes the importance of value generation, promoting customer focus, eliminating waste, and continuous improvement. It encourages a holistic approach to project assessment, recognizing the multifaceted nature of success. This new paradigm suggests further research into strategies that assess cost, schedule, and value in construction projects.