How would you define this big idea?
An infrastructure is defined in NSF Critical Resilient Interdependent Infrastructure Systems and Processes (CRISP), "as a network of human-made systems and processes that function cooperatively and synergistically to produce and distribute a continuous flow of essential goods and services." Examples of infrastructure components are roads, energy transmission grids, medical services, and flood protection levees. The U.S. has defined 16 critical infrastructure sectors a list of which can be found at here.
Rinaldi, S.M., Peerenboom, J.P., Kelley, T.K., Identifying, Understanding, and Analyzing Critical Infrastructure A classic reference paper in this area that highlighted the need for analyzing infrastructures as interacting systems and not just isolated entities.
Colleagues: John Crittenden, Nancey Leigh, Iris Tien