The Roads Must Roll

The Roads Must Roll is a science fiction short story by Robert A. Heinlein about wide, rapidly moving passenger platforms (like the mechanical walkways in some real-life airports but much faster). These roads combine the features of highways and highway restaurants, and all goes smoothly until there's union trouble. The men who maintain the roads get around beneath them via motorized, gyroscopically stabilized unicycles like the real-life Segway.

The story also mentions the In social theory of functionalism. The functionalists were a faction of workers maintaining giant slidewalks that provided nearly all transportation in the US. They shut some of them down to demonstrate their power. According to the story, functionalism was a popular belief in the 1920s.