New research is suggesting that the layout of subway systems around the world is converging on some sort of ideal pattern:
After decades of urban evolution, the world’s major subway systems appear to be converging on an ideal form.
On the surface, these core-and-branch systems — evident in New York City, Tokyo, London or most any large metropolitan subway — may seem intuitively optimal. But in the absence of top-down central planning, their movement over decades toward a common mathematical space may hint at universal principles of human self-organization.
Understand those principles, and one might “make urbanism a quantitative science, and understand with data and numbers the construction of a city,” said statistical physicist Marc Barthelemy of France’s National Center for Scientific Research.
World’s Subways Converging on Ideal Form [Wired Science]