physiological constants and constraints

I wonder how much discontinuity is created by physical, in particular physiological, constraints?  And I wonder how much those discontinuities are exploited in investment decisions and forecasts.  I'm thinking about things such as body sizes, minimum sleep periods, and elimination functions and their relationship with economies of scale and extrapolation of product sizes and uses.  For example, cars have a hard time getting smaller than a certain limit because people generally fit within a certain band (and so you get oddly proportioned vehicles such as a Smart).

City = Green

I'm pretty sure this article says basically the same thing as the New York Times Magazine piece a few years ago (which I can't find at all).  But that's fine with me as the message is more relevant than ever.

street grids

Infrastructure seems to have some role to play in the success of cities (a less macro version of guns, germs and steel), and so I wonder if a grid pattern close to an ideal for city streets? After returning to New York and seeing how traffic generally moves, even when the streets are apparently full, I wonder if the combination of multiple paths moving in the same direction with smallish streets and smallish blocks is actually quite efficient where there is no pricing or limited access.

A grid would be somewhat self-balancing (as a street backs up, traffic naturally diverts to parallel streets if there are "block-the-box" rules, have some redundancy (with no absolute bottlenecks, no one point locks up the system or cuts off an area), and deliver some information (although not information rich, a quick glance at a street suggests is somewhat predictive of local and even less local traffic - in part because of the self-balancing aspects).

And this is most interesting as it isn't clear that the road designers were worried about traffic.