Introduction Big infrastructures are complicated to design and operate and expensive to build and maintain. They have other features too, but these are the characteristics that dominate academic research and writing in science and technology studies, in urban and social theory and in various forms of historical and economic geography. Across these disciplines common projects include those showing how infrastructures are variously shaped by forms of urban and regional governance, by local and national politics and by the aspirations of city planners, engineers and entrepreneurs. In analysing these processes some commentators focus on the confl icts and tensions involved. Others highlight inequalities arising from the radically different forms of provision that characterise cities in different parts of the world. Meanwhile, for those interested in sustainability, urban infrastructures represent important sites of actual or potential renewal, and of transition towards more effi cient or lower carbon regimes. Together, these and other such lines of enquiry constitute diverse but nonetheless skewed traditions in which matters of provision and supply take centre stage.