[kalleth]

It's not the "I, Robot" books, it's the quadrilogy sometimes called the "Robot" series (confusing, I know). "The Caves of Steel", "The Naked Sun", "Robots of Dawn", "Robots and Empire".

These are without a doubt my favourite of Asimov's books :)

Earth has evolved to a point where the population lives in Cities (capitalisation is important!) -- massive, hundreds of square miles completely enclosed with no outside areas at all. They might as well be space stations.

Transit within these cities takes place on 'strips' for local transport -- think of them as 'lanes' on a freeway. The first strip you step on to is an acceleration strip (onramp), which gets you up to speed to then step onto faster strips.

There's also an "Expressway", which is basically a metro, which you step onto from the fastest strip (I think there is an acceleration strip too) which takes over when you want to go longer distances.

Then for even longer distances you have aircars (planes!).

It's a really good system, but only for highly, highly urbanised areas. I think there's only 2 or 3 cities on the planet at the moment truly dense enough. New York, and perhaps central London.

[mturmon]

And in those stories, you can definitely see Asimov's New York City bias. History pointed like an arrow to a future in which cities are...hyper-developed versions of where you grew up and where you prefer to live!