This book is based on the underlying premise that much can be learned from contemporary thinking about the treatment of complexity, uncertainty, risk-taking and the importance of context in decision making for planning, in fields where these concepts have long been deployed in complex problem-solving. It explores the sophisticated theoretical approaches which have been developed in order to analyse the issues surrounding that complexity. In so doing, the book discusses the overriding influence of complexity theory on the whole field of risk and uncertainty as it impacts on all stages of the project life-cycle. It furthermore examines various decision-support methods, tools and techniques that have been developed and employed by different professions and disciplines with the aim of addressing risk, uncertainty and complexity in planning in a range of different contexts. The book especially explores the parameters of these different contexts and their characteristics in an effort to identify both generic and context-specific lessons that may be of value to planning exercises for Mega Transport Projects.