I'd guess that Heinlein was aware of it and scaled it up in his imagination.
The Roads must roll — they are the arteries of the nation. When they stop, everything stops. Factories idle, food rots, men starve. The nation cannot live without its Roads.
A thousand feet wide, level as a floor, strip after strip moving past in ordered procession. The slow strips on the outside moved at five miles an hour; the inner ones faster and faster, until the express strip in the center rushed past at a hundred miles an hour.
-- The Roads Must Roll, Astounding Science Fiction, June 1940.
