Designing Flexibility into Construction Decisions challenges one of the most dangerous assumptions in infrastructure development: that certainty must replace flexibility once a project begins. Across industries and geographies, large-scale projects consistently suffer from cost overruns, delays, and structural rigidity—not because of technical failure, but because critical decisions are made before sufficient knowledge exists to justify them. This book argues that the real problem is not uncertainty, but the way organizations commit under uncertainty. Drawing on years of experience at the interface between geotechnical reality and project decision-making, Andi presents a rigorous framework for understanding how commitments form, harden, and propagate through infrastructure systems. He introduces the concept of commitment architecture—the system of physical, contractual, financial, and organizational decisions that determine whether a project remains adaptable or becomes locked into fragile assumptions. Through structured analysis and cross-disciplinary insights, this book explores: • Why construction is structurally irreversible—and why most frameworks fail to account for it • How early design and contract decisions silently become capital locks • The mechanics of the commitment cascade, where early assumptions eliminate future options • Why traditional risk management fails to preserve strategic flexibility • How to design projects that maintain optionality without sacrificing execution discipline This is not a book about how to build. It is a book about how to decide—before building begins. Written for developers, infrastructure investors, project directors, and government decision-makers, this work provides a new lens for evaluating risk, timing commitment, and preserving value in long-horizon projects. Because in infrastructure, the cost of being wrong is not paid when failure occurs— it is locked in when the decision is made.