When in 1989 the authors started research on infrastructure, they did not foresee that this would lead to a long-term involvement in this area. Our beginning happened to coincide with the publication of David Aschauer's article on public capital and productivity, which induced a large flow of publications in this field. Infrastructure has indeed been a hot topic in policy and research during the past decade. It is surprising, however, that the number of monographs on spatial and economic impacts of infrastructure has remained very limited. The aim of this book is to contribute to the literature in a consolidated way. A distinguishing feature of our book is that we analyze infrastructure impacts using various methods (both modelling and non-modelling) at a variety of spatial levels (from local to international). Other special features are that we make ample use of 'accessibility' as a bridge concept between the areas of infrastructure and the economy. Finally, we not only treat transport infrastructure projects as given, as is the usual approach in infrastructure impact research, but we also analyze the factors influencing infrastructure supply. We have adopted a mainly non-technical approach throughout most of the book. This means that it can also be used by readers without a strong back­ ground in statistics, modelling or micro-economics.