Mixed-use development

These days with high gas prices and awful traffic, we are starting to hear more about mixed-use development, generally with terms like "urban villages" and such. The point seems to be that people can live next to where they work and have short commutes. But that is, for the most part, just wishful thinking, and entirely misses the point of being in a city, that being the access you have to a wide variety of jobs and leisure activities. A city is more than just a bunch of villages concatenated together.

No, the real point of mixed use development is just plain old efficiency. Things like raods, transit, and sewers are expensive to build, and they have to be built to meet the peak demand. The neat thing about mixed-use is that the peak demands of the uses generally come at different times, so the overall peak is only as big as that of the biggest use. If you've built roads and parking lots to support an office park, you can probably build a shopping mall next to it with only a little extra road capacity and parking, since the office park is empty on evenings and weekends, which is exactly when the shopping mall is full.