Another problem is that the streets (despite taking up so much space) aren't actually sufficient for the needs, and are resultingly clogged with traffic. Many utilities (water, gas, electric, communications, sewage) can only be accessed/maintained by digging up roads, which further impacts on traffic issues.
So how would you go about designing a city from scratch? A layered approach, with three main layers:
- Utilities layer
- Transportation layer
- Habitation/work/recreation layer
The habitation/work/recreation layer is where people would spend most of their time.
The layers can consist of several levels. This facilitates water being separated from electricitiy in the utilities layer (generally a wise choice). The habitation/work/recreation layer has multiple levels just like our current high-rise buildings.
A key element of the layer principle is that only the habitation/work/recreation layer requires access to sunlight. The entire transportation layer should be underground. This makes much more efficient use of space. However, it does not mean that buildings can be packed that much more tightly, as this would mean that sunlight does not penetrate to their lower floors. Instead, the spaces between buildings are maintained by using the spaces between them for recreational space: parks; football pitches; golf courses; tennis courts; etc.
A similar approach should be taken within the buildings themselves, which the less natural-light-dependent functions, or those used infrequently, taking up the space furthest from the windows.