Chelonian Symbolism

I feel as if the only way to begin this is by writing about the #1 most important chapter in the entire book: Chapter 3, the turtle chapter.
Please note the earlier statement that this is an important chapter was merely sarcasm. I wouldn't call this "unimportant", per se, it's just that a literal-minded realist such as myself wouldn't immediately consider it to be important; I honestly looked up the chapter up to make sure that it wasn't filler like I originally thought it was.
The problem is that I don't see symbolism just by looking at something, whereas the chapter is apparently ripe with symbolism. I, being an overly-logical person, tend to look at words, not between them, so a narrative about the "perils" of a turtle crossing the road seemed like exactly that. Of course, it obviously meant something to Steinbeck, else he wouldn't have put it in there.
It appears that the turtle is a symbol for the Oklahoma farmers' plights. The fact that it is a turtle crossing the road is, apparently, foreshadowing of sorts, in that it symbolizes the journey that the Joads are going to embark on later on. The fact that it is a turtle, an animal known for its slow speed and its shell, serves as a metaphor for how the Joads carry everything they own with them (a turtle always has its shell, which is both protection and a home).
Roads always symbolize a journey, so, again, the journey the Joads will embark on.
One person swerves to avoid the turtle, I guess symbolizing the kind people meet will along the way. Another still deliberately hits the turtle. One can only assume this is for the people who will hinder the Joad's progress. The turtle, though for a while wobbling on its shell, eventually gets back on its feet and continutes on, showing the Joads will still press on.
And here, I thought it was just a turtle.