In this and the following chapters we review the experience from a large number of megaprojects, including the Channel tunnel and the links across Great Belt and Øresund, all three multibillion-dollar projects. Although we subject these projects to critical scrutiny, our objective is not to criticise them, even where they have underperformed, but to learn constructively from experience by identifying lessons that may prove useful in improving future decisions regarding megaprojects. Given the large amounts of money spent on major transport infrastructure projects, it is remarkable how little data and research are available that would help answer the two basic questions: (i) whether such projects have the intended effects; and (ii) how the actual viability of such projects compares to projected viability. Therefore, in addition to transport projects, we have found it pertinent to review data and research from other types of infrastructure project and to compare experience from these projects with experience from the transport sector. In this manner, we will review data from several hundred large projects. In this chapter we focus on the costs of megaprojects. In Chapters 3 and 4 we consider the demand for, and viability of, such project.

The problem of cost overrun

Cost overruns in major transport infrastructure projects are widespread.