ABSTRACT
Transportation facilities are not the only important aspects of the physical infrastructure in a city. Clean drinking water and sewage systems to carry away unhealthy waste are necessary to maintain health. Power is needed for industry and homes, so the means to produce and distribute sources of it must be available. Information and documents need to be circulated within the city and elsewhere via communications systems. Finally, distribution networks have to be in place to enable the exchange of produce to feed the urban population.
