Symbolism, Imagery, Allegory
Don't stand in the way of progress or you'll get run over... probably by a Model T. The Model T is a big character in Ragtime, symbolizing progress and all the fears that come with it.
Let's check out the birth of the Model T. This old-timey automobile was put together on the first assembly line, allowing it to be assembled for super-cheap and making the good ol' auto accessible to the masses. Great, right? Well, sure. But the assembly line was based on the mechanics of a slaughterhouse. That's pretty grisly, and very symbolic.
J.P. Morgan thinks that the assembly line is symbolic of reproduction:
Has it occurred to you that your assembly line is not merely a stroke of industrial genius but a projection of organic truth? (20.5)
He's got a point here. The assembly line puts together, bit by bit, a moving vehicle. That's pretty nifty. But think about what else it does. Assembly lines are the first stages of creating a workforce with reduced skill. Instead of having one dude with crazy mechanical skills put together an entire car, you now have a bunch of guys learning how to put together one part of a car.
The assembly line is, in effect, a disassembly line of labor skillz. And hey, you know what else was called a "disassembly line"? A slaughterhouse.
This is symbolic of the fears people at the turn of the 20th century had about mechanization. It seemed, to the hat-wearing populace of the early 1900s, that new-fangled inventions would tear the country apart. People would lose skills. The machines would take over. The robot overlord apocalypse would be nigh.
Let's also check out the role of cars in Ragtime. A group of bigoted firemen poop in Coalhouse's car, which sets about a series of events that gets a bunch of people being killed. The car, in Coalhouse's case, is an extension of his pride. His pride is wounded, and he lashes out.
This kind of thinking is still super prevalent today: have you ever seen anyone fly off the handle because their car got keyed? Have you seen Ferris Bueller's Day Off? Cars can become an extension of the car-owner.
This I-love-my-car-more-than-I-love-life attitude brings us back to the idea of progress being terrifying. Much as an assembly line compartmentalizes labor and can reduce all-around skill, technological progress was seen to compartmentalize, and reduce, humanity.
The fear is that when humans can transfer human emotions to objects and say "That car is my pride/freedom/independence" or "My smartphone is my brain/social life/memory" they lose the ability to retain pride, or brains within themselves.
Having survived more than a century with ye olde horseless carriage, we know that cars haven't left us with a broken society. But the fears that surrounded technology in the early 20th century are the same fears that we harbor today. Replace "Model T" with "Google Glass" and you have an idea of how scary (and yes, exciting) the automobile was.