I think the parent poster meant cities where the road rules amount to a functioning car horn. The roads of Japan are nothing like Cairo/Istanbul etc. There are a lot of cars - but they drive in an orderly, predictable manner.

On a related note: http://en.wikipedia.org/wiki/Yurikamome

In Tokyo they already have an automated transit system that is basically a truck on rails. See this image to get a better picture: http://en.wikipedia.org/wiki/File:Model_7000-Fourth_of_Yurik...

Yurikamome is just a driverless train.

It's not a train in the classical sense - it has rubber tires. More like a truck confined to a rail.