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.