ktvu's bob mackenzie first brought us the story of "the triple ten years ago. >> reporter: those horseless carriages were mucking up the air and scaring the horses. of course you to be rich to own an automobile, which didn't add to their popularity with everyone else. as the second decade began, the auto owned the streets in san francisco and other big up toes, but it was still the rich who owned them. henry ford changed all of that. instead of making cars one at a time, the ford factory mass- produced them with an idea called osembly lines. each worker did the same job over and over, enabling the plant to crank out a new car every ten minutes. at last, regular folks could take to the roads, and in the roaring $20s, they did. charging up and down the streets of san francisco in an exhilarating triumphant of machinery over topography. but outside city limits there were no paved roads and no road signs. cloud of dust race raise by one automobile made visibility pretty chancey for anyone behind. nevertheless, car owners took their spins in the country, lurching in and out of ruts and bouncing