An invisible network of digital technology systems underlies the highly visible networks of roads, waterways, satellites, and power-lines. Increasingly, these systems are becoming the "infrastructure's infrastructure," providing a crucial array of data on network demand, performance, reliability, and security. Digital Infrastructures presents an interdisciplinary analysis of the technological systems that envelop these networks. The book balances analyses of specific civil and environmental infrastructures with broader policy and management issues, including the challenges of using IT to manage these critical systems under crises conditions.