One of the interesting things about this book I'm reading from 1968 is that Simak is using Heinlein's "rolling road" concept, originally published in the 1940 short story The Roads Must Roll.

Basically you have multiple parallel rows of moving slidewalks, each slightly faster than the next. The outermost is barely at a walking speed, the next is a little faster, and so on, until you reach the inner strip running at 100 mph. There are no cars, you just ride the road, stepping between strips to speed up or slow down.

I just thought it was interesting to see this come up almost 3 decades later and by a different author.

It's an intriguing idea, though entirely impractical from a technological standpoint (or trying to stand up in a 100 mph wind). But I have seen an illustration of a system that might actually work. It's greatly simplified, with just 2, 4, and 6 mile per hour strips, with the innermost strip equipped with benches so you could sit down while moving.