The construction of large-scale structures to pro vide fixed links across rivers and straits has important social and economie effects. To these must be added environmental changes, which in turn influence the socioeconomic conditions of large regions in various ways. The present volume makes a fundamental contribution to our understanding of situations, phenomena, and problems connected with the construction of large bridges and tunnels. The volume was produced with the collaboration of researchers of the Internation Institute for Applied Systems Analysis (IIASA), the Istituto Superior de Ciencias do Trabalho e da Empresa (ISCTE), the London School of Economie and Political Sciences, and the Consiglio Nazionale delle Ricerche (CNR). It is therefore a volume that concerns scholars in the social sciences, but also and above all officials working in local and national public administrations who are responsible for planning, approving, and managing these large-scale structures in all of the phases of their construction and operation.