A theory of infrastructure: how does infrastructure work?

When we think of infrastructure, we typically think of roads, railways, airports, electricity lines, wastewater treatment plants and similar. Each is designed, operated and maintained by specialists in that type of infrastructure. Investors and underwriters might even specialise in particular types of infrastructure projects. Yet every kind of infrastructure is wholly linked to other infrastructure. The airport cannot be effective without road access, electricity and water supply, wastewater and garbage removal, or communications. Each piece of infrastructure is an entity in its own right, a whole, while also being a part of other infrastructures, other wholes. We need to be able to think of infrastructure in isolation. Still, we must also appreciate that it fulfils a number of roles and is part of many other infrastructures. A road is not just a road. It is the access to the airport and allows passengers and freight to continue their journey on land.