The Past Through Tomorrow by Robert A. Heinlein

passengers onto the slower ways, dropping them on the exposed rollers and rotors down inside, and snapping them up against the roof.
    “Over three thousand people were killed in that one accident, and there was much agitation to abolish the roads. They were even shut down for a week by presidential order, but he was forced to reopen them again. There was no alternative.”
    “Really? Why not?”
    “The country had become economically dependent on the roads. They were the principal means of transportation in the industrial areas—the only means of economic importance. Factories were shut down; food didn’t move; people got hungry—and the President was forced to let them roll again. It was the only thing that could be done; the social pattern had crystallized in one form, and it couldn’t be changed overnight. A large, industrialized population must have large-scale transportation, not only for people, but for trade.”
    Mr. Blekinsop fussed with his napkin, and rather diffidently suggested, “Mr. Gaines, I do not intend to disparage the ingenious accomplishments of your great people, but isn’t it possible that you may have put too many eggs in one basket in allowing your whole economy to become dependent on the functioning of one type of machinery?”
    Gaines considered this soberly. “I see your point. Yes—and no. Every civilization above the peasant-and-village type is dependent on some key type of machinery. The old South was based on the cotton gin. Imperial England was made possible by the steam engine. Large populations have to have machines for power, for transportation, and for manufacturing in order to live. Had it not been for machinery the large populations could never have grown up. That’s not a fault of the machine; that’s its virtue.
    “But it is true that whenever we develop machinery to the point where it will support large populations at a high standard of living we are then bound to keep that machinery running, or suffer the consequences. But the real hazard in that is not the machinery, but the men who run the machinery. These roads, as machines, are all right. They are strong and safe and will do everything they were designed to do. No, it’s not the machines, it’s the men.
    “When a population is dependent on a machine, they are hostages of the men who tend the machines. If their morale is high, their sense of duty strong—”
    Someone up near the front of the restaurant had turned up the volume control of the radio, letting out a blast of music that drowned out Gaines’ words. When the sound had been tapered down to a more nearly bearable volume, he was saying:
    “Listen to that. It illustrates my point.”
    Blekinsop turned an ear to the music. It was a swinging march of compelling rhythm, with a modern interpretive arrangement. One could hear the roar of machinery, the repetitive clatter of mechanisms. A pleased smile of recognition spread over the Australian’s face. “It’s your Field Artillery Song, The Roll of the Caissons , isn’t it? But I don’t see the connection.”
    “You’re right; it was the Roll of the Caissons , but we adapted it to our own purposes. It’s the Road Song of the Transport Cadets . Wait.”
    The persistent throb of the march continued, and seemed to blend with the vibration of the roadway underneath into a single tympany. Then a male chorus took up the verse:
“ Hear them hum!
    Watch them run!
    Oh, our job is never done,
    For our roadways go rolling along!
    While you ride;
    While you glide;
    We are watching ‘down inside’,
    So your roadways keep rolling along!
    “ Oh, it’s Hie! Hie! Hee!
    The rotor men are we—
    Check off the sectors loud and strong ! (spoken) One! Two! Three!
    Anywhere you go
    You are bound to know
    That your roadways are rolling along!
    (Shouted) KEEP THEM ROLLING!
    That your roadways are rolling along! ”
    “See?” said Gaines, with more animation in his voice. “See? That is the real purpose of the United